JP2010045249A - Semiconductor light emitting device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device which is reducible in temperature dependency of optical output, and to provide a method of manufacturing the same. <P>SOLUTION: A substrate 10 is provided between a lower DBR layer 18 and a lower cladding layer 11, i.e., in a cavity. Consequently, the effective resonator length of a semiconductor laser 1 becomes longer by the thickness of the substrate 10 and oscillations are generated in a plurality of axis modes, so even when an oscillation wavelength is shifted due to temperature change, a wavelength offset amount at the oscillation frequency having been shifted is equal to or substantially equal to a wavelength offset amount at which the optical output becomes maximum in one of the axis modes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device that emits laser light in the stacking direction and a method for manufacturing the semiconductor light emitting device, and more particularly, to a semiconductor light emitting device that can be suitably applied to applications requiring stable light output and a method for manufacturing the semiconductor light emitting device.

  A surface emitting semiconductor laser, unlike a conventional Fabry-Perot resonator semiconductor laser, emits light in a direction perpendicular to the substrate, and has a number of resonator structures in a two-dimensional array on the same substrate. In recent years, it has attracted attention in the field of data communication and the like.

This surface-emitting type semiconductor laser generally has a mesa resonator structure in which a lower DBR layer, a lower cladding layer, an active layer, an upper cladding layer, and an upper DBR layer are stacked in this order on a substrate ( For example, see Patent Document 1). In such a semiconductor laser, the oscillation wavelength λx is determined by the effective resonator length of the resonator structure, and the magnitude of the optical output is shifted by a predetermined magnitude from the emission wavelength λy corresponding to the band gap of the active layer. It becomes the largest at the wavelength (λy + Δλ ₀ ) (FIGS. 21A and 21B). Therefore, usually, when the temperature of the laser, for example, 25 ° C., so that the oscillation wavelength λx is equal to [lambda] y + [Delta] [lambda] _0, the resonator structure and the active layer is formed. 21A shows an example of the temperature dependence of the gain, and FIG. 21B shows an example of the temperature dependence of the oscillation wavelength and the emission wavelength corresponding to the band gap of the active layer. It is a thing.

JP 2001-332812 A

However, when the temperature of the laser rises from, for example, 25 ° C. to 60 ° C., the refractive index increases and the effective resonator length increases. Further, as the temperature rises, the band gap of the active layer becomes smaller, and the emission wavelength of the active layer shifts to the longer wavelength side. At this time, since the shift amount of the emission wavelength of the active layer is larger than the effective resonator length increment, the deviation between the effective resonator length and the emission wavelength of the active layer increases by Δλ ₀ as the temperature rises. In other words, the light output fluctuated (becomes smaller).

  The present invention has been made in view of such problems, and an object of the present invention is to provide a semiconductor light-emitting element capable of reducing temperature dependency of light output and a method for manufacturing the same.

  The semiconductor light emitting device of the present invention comprises a lower multilayer reflector, a lower clad layer, an active layer, an upper clad layer, and an upper multilayer reflector in order. A semiconductor substrate is provided inside the lower multilayer reflector or between the lower multilayer reflector and the lower cladding layer.

  In the semiconductor light emitting device of the present invention, a semiconductor substrate is provided inside the lower multilayer reflector or between the lower multilayer reflector and the lower cladding layer. As a result, the effective resonator length of the semiconductor light emitting element is increased by the thickness of the semiconductor substrate, so that oscillation occurs in a plurality of axial modes.

  According to a first method of manufacturing a semiconductor light emitting device of the present invention, a semiconductor layer including a lower clad layer, an active layer, an upper clad layer, and an upper multilayer reflector in order is formed on one surface of a semiconductor substrate. Forming a lower multilayer reflector on the other surface of the substrate;

  In the first method for manufacturing a semiconductor light emitting device of the present invention, a semiconductor substrate is formed between the lower multilayer reflector and the lower cladding layer. As a result, the effective resonator length of the semiconductor light emitting element is increased by the thickness of the semiconductor substrate, so that oscillation occurs in a plurality of axial modes.

  The second method for manufacturing a semiconductor light emitting device of the present invention includes a first lower multilayer reflector, a lower cladding layer, an active layer, an upper cladding layer, and an upper multilayer reflector in order on one surface of a semiconductor substrate. The method includes forming a semiconductor layer and forming a second lower multilayer mirror on the other surface of the semiconductor substrate.

  In the second method for manufacturing a semiconductor light emitting device of the present invention, a semiconductor substrate is formed inside the lower multilayer mirror. As a result, the effective resonator length of the semiconductor light emitting element is increased by the thickness of the semiconductor substrate, so that oscillation occurs in a plurality of axial modes.

According to the semiconductor light emitting device of the present invention and the first and second manufacturing methods of the semiconductor light emitting device of the present invention, the effective resonator length of the semiconductor light emitting device is increased by the thickness of the semiconductor substrate. Oscillation occurs in multiple axis modes. As a result, even if the difference (wavelength offset amount) between the effective resonator length and the emission wavelength of the active layer changes due to temperature change, the wavelength offset in one of the multiple axis modes The amount is equal to or close to the wavelength offset amount (Δλ ₀ described above) when the light output becomes maximum. As a result, the wavelength at which the light output is maximized changes slightly due to temperature change, but the light output magnitude hardly changes. Therefore, the temperature dependence of the light output can be reduced as compared with the case where the semiconductor substrate is not provided inside the lower multilayer reflector or between the lower multilayer reflector and the lower cladding layer.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]
FIG. 1 shows an example of a cross-sectional configuration of a semiconductor laser 1 according to the first embodiment of the present invention. Note that FIG. 1 is a schematic representation and is different from actual dimensions and shapes. 2A shows the temperature dependence of the gain of the semiconductor laser 1 of FIG. FIG. 2B shows the temperature dependence of the oscillation wavelength λx of the semiconductor laser 1 and the emission wavelength λy corresponding to the band gap of the active layer 12 described later.

  The semiconductor laser 1 of the present embodiment is a surface emitting semiconductor laser that emits light in the stacking direction, and has a stacked structure on both surfaces of the substrate 10. Specifically, for example, as shown in FIG. 1, the semiconductor laser 1 includes a lower clad layer 11, an active layer 12, an upper clad layer 13, a current confinement layer 14, an upper DBR on one surface of a substrate 10. A layer 15 and a contact layer 16 are sequentially provided from the substrate 10 side, and a lower DBR layer 18 is provided on the other surface of the substrate 10 (on the surface opposite to the lower cladding layer 11). In other words, the semiconductor laser 1 has a substrate 10 provided between a pair of resonator mirrors constituted by the upper DBR layer 15 and the lower DBR layer 18, that is, in a cavity, and has a plurality of axial modes (for example, As shown in FIG. 2B, oscillation is possible at λx1, λx2, and λx3 (three wavelengths of λx1 <λx2 <λx3).

  The upper part of the laminated structure in the semiconductor laser 1, specifically, the lower clad layer 11, the active layer 12, the upper clad layer 13, the current confinement layer 14, the upper DBR layer 15, and the contact layer 16 has a mesa extending in the lamination direction. A portion 17 is formed. The mesa portion 17 has a cylindrical shape with a width of about 20 μm, for example. On the other hand, the lower part of the stacked structure in the semiconductor laser 1, specifically, the lower DBR layer 18 is formed at least in a region facing the mesa unit 17, for example, over the entire back surface of the substrate 10. ing.

  In the present embodiment, the lower DBR layer 18 corresponds to a specific example of the “lower multilayer reflector” of the present invention, and the upper DBR layer 15 is a specific example of the “upper multilayer reflector” of the present invention. The substrate 10 corresponds to a specific example of the “semiconductor substrate” of the present invention.

  The substrate 10 corresponds to the lowermost layer (substrate) for film formation (for example, epitaxial crystal growth and deposition), and is, for example, an n-type GaAs substrate. The thickness of the substrate 10 is, for example, a value within the range of 100 μm or more and 600 μm or less. Examples of the n-type impurity include silicon (Si) and selenium (Se).

The lower cladding layer 11 is made of, for example, n-type Al _x1 Ga _1-x1 As (0 ≦ x1 <1). The upper cladding layer 13 is made of, for example, p-type Al _x2 Ga _1-x2 As (0 ≦ x2 <1). Examples of the p-type impurity include zinc (Zn), magnesium (Mg), and beryllium (Be).

The active layer 12 is made of a material having a band gap corresponding to a wavelength band that is difficult to be absorbed by the substrate 10 and has, for example, an undoped In _x3 Ga _1-x3 As / GaAs quantum well structure (0 <x3 <1 ). For example, as shown in FIGS. 2A and 2B, the active layer 12 has a plurality of oscillation wavelengths (for example, λ ₁ , λ ₂ , λ ₃ ) (λ ₁ <λ ₂ < It is made of a material that has a maximum gain (for example, gain at a position indicated by P1 in FIG. 2A) at 25 ° C. at _one oscillation wavelength (for example, λ ₁ ) among λ ₃ ). More specifically, the active layer 12 includes, for example, a plurality of oscillation wavelengths (for example, λ ₁ , λ ₂ , λ ₃ ) at 25 ° C. as shown in FIGS. The difference Δλa (= λ ₁ −λ ₄ ) between one oscillation wavelength (for example, λ ₁ ) and the emission wavelength λ ₄ corresponding to the band gap of the active layer 12 at 25 ° C. is Δλm (when the maximum gain is reached). , And is made of a material that is equal to the oscillation wavelength λx and the emission wavelength λy (difference between <λx). For example, when the active layer 12 has an undoped In _x3 Ga _1-x3 As / GaAs quantum well structure, the In composition ratio x3 has a plurality of oscillation wavelengths at 25 ° C. (for example, λ ₁ , λ ₂ , Λ ₃ ) at one oscillation wavelength (for example, λ ₁ ), it is equal to a value that gives a maximum gain at 25 ° C.

Here, the fluctuation amount with respect to the temperature change of the oscillation wavelength λx and the fluctuation amount with respect to the temperature change of the emission wavelength λy are different from each other, and the fluctuation amount with respect to the temperature change of the emission wavelength λy is different. Bigger than. Therefore, the difference Δλ (= λx−λy) between the oscillation wavelength λx and the emission wavelength λy becomes smaller as the temperature rises. Therefore, when the active layer 12 is made of a material such that Δλa is equal to Δλm, the temperature at which the difference Δλx2 between the oscillation wavelength λx2 and the emission wavelength λy becomes Δλm is higher than 25 ° C. (for example, The temperature at which the difference Δλx3 between the oscillation wavelength λx3 and the emission wavelength λy becomes Δλm exists on the higher temperature side (for example, 60 ° C). In FIG. 2B, the difference Δλa at 25 ° C. is Δλm, and one oscillation wavelength (for example, λ ₅ , λ ₆ , λ ₇ ) at 40 ° C. For example, the difference Δλb (= λ ₆ −λ ₈ ) between λ ₆ ) and the emission wavelength λ ₈ corresponding to the band gap of the active layer 12 at 40 ° C. is Δλm, and a plurality of oscillations at 60 ° C. wavelength _{(e.g., λ 9, λ 10, λ} 11) as one of the oscillation wavelength of the (e.g., lambda _11), the difference Δλc the emission wavelength lambda ₁₂ corresponding to the band gap at 60 ° C. of the active layer 12 (= lambda ₁₁ -λ ₁₂ ) is illustrated as Δλm.

In general, it is known that the gain of the surface emitting semiconductor laser is maximized when the difference Δλ between the oscillation wavelength λx and the emission wavelength λy corresponding to the band gap of the active layer has a predetermined magnitude. For example, when the active layer 12 has an In _x3 Ga _1-x3 As / GaAs quantum well structure, the gain of the surface emitting semiconductor laser is maximized when Δλm is 13 nm. When the active layer 12 is made of an AlGaInP-based material having a wavelength band of 650 nm to 670 nm, the gain of the surface emitting semiconductor laser is maximized when Δλm is 10 nm.

  The oscillation wavelength λx can be confirmed by measuring the spectral distribution of the laser light emitted from the semiconductor laser 1. Further, the emission wavelength λy is activated by removing, for example, the substrate 10 and the lower DBR layer 18 from the semiconductor laser 1, exposing the lower cladding layer 12, and irradiating the lower cladding layer 12 with a predetermined laser beam. It can be confirmed by measuring the spectral distribution of the light emitted from the layer 12.

The current confinement layer 14 has a current confinement region 14A in a region from the side surface of the mesa portion 17 to a predetermined depth, and has a current injection region 14B in the other region (the central region of the mesa portion 17). Yes. The current injection region 14B is made of, for example, p-type Al _x4 Ga _1-x4 As (0 <x4 ≦ 1). The current confinement region 14A includes, for example, Al ₂ O ₃ (aluminum oxide), and oxidizes high-concentration Al contained in the oxidized layer (not shown) from the side surface of the mesa portion 17. It is formed. Accordingly, a region of the active layer 12 facing the current injection region 14B corresponds to the current injection region of the active layer 12, that is, the light emitting region 12A.

  The current confinement layer 14 does not always need to be provided between the upper cladding layer 13 and the upper DBR layer 15. For example, although not shown, several layers from the active layer 12 side in the upper DBR layer 15 are provided. It may be provided in place of the low refractive index layer at a remote portion of the low refractive index layer.

The upper DBR layer 15 has a laminated structure in which, for example, a low refractive index layer (not shown) and a high refractive index layer (not shown) are alternately laminated, and the uppermost layer has a high refractive index. ing. Low refractive index layer, for example a thickness of λ ₁ / 4n ₁ p-type _{Al x5 Ga 1-x5 As (} 0 <x5 <1), the high refractive index layer, for example a thickness of λ ₁ / 4n ₂ p Each of them is composed of a type Al _x6 Ga _1-x6 As (0 ≦ x6 <x5). Here, n ₁ is the refractive index of the low refractive index layer. n _{2 is a} refractive index of the high refractive index layer, and is larger than n ₂ .

The low refractive index layers and high refractive index layers in the upper DBR layer 15 is not limited to the above configuration, for example, in terms of maintaining its optical thickness lambda _1/4, it is constituted by a plurality of layers It may be.

The contact layer 16 is made of, for example, p-type Al _x7 Ga _1-x7 As (0 ≦ x7 <1).

The lower DBR layer 18 has, for example, a stacked structure in which low refractive index layers (not shown) and high refractive index layers (not shown) are alternately stacked. The low refractive index layer is, for example, n-type Al _x8 Ga _1-x8 As (0 <x8 <1) having a thickness of λ ₁ / 4n ₃ , and the high refractive index layer is, for example, having a thickness of λ ₁ / 4n ₄ Each is composed of n-type Al _x9 Ga _1-x9 As (0 ≦ x9 <x8). Here, n ₃ is the refractive index of the low refractive index layer. n ₄ is the refractive index of the high refractive index layer, and is larger than n ₃ .

Incidentally, on the low refractive index layer and the high refractive index layer of the upper DBR layer 15 and the lower DBR layer 18 is not limited to the above configuration, for example, it kept its optical thickness lambda _1/4, You may be comprised by multiple layers. The lower DBR layer 18 may be formed of a material other than the semiconductor, for example, different dielectric film (e.g. SiN, SiO ₂₎ of the refractive index are laminated alternately with an optical thickness of lambda _1/4 a It may be configured. However, in that case, in order to ensure conduction between the lower electrode 21 and the substrate 10, a part of the lower DBR layer 18 is removed to expose the back surface of the substrate 10, and the lower electrode is exposed on the exposed surface. 21 is preferably formed.

In this semiconductor laser 1, an insulating layer 19 made of, for example, SiO ₂ is provided from the side surface to the skirt of the mesa portion 17. In the semiconductor laser 1, an upper electrode 20 is formed on the upper surface of the mesa portion 17 (contact layer 16). The upper electrode 20 has an annular shape having an opening in the central region. A lower electrode 21 is formed on the surface (lower surface) of the lower DBR layer 18.

  Here, the upper electrode 20 has a structure in which, for example, titanium (Ti), platinum (Pt), and gold (Au) are laminated in this order from the substrate 10 side, and is electrically connected to the contact layer 16. Yes. The lower electrode 21 has, for example, a structure in which an alloy of gold (Au) and germanium (Ge), nickel (Ni), and gold (Au) are stacked in this order from the substrate 10 side. It is connected to the.

  The semiconductor laser 1 according to the present embodiment can be manufactured as follows, for example.

For example, in order to manufacture a GaAs-based surface emitting semiconductor laser, for example, a stacked structure on the substrate 10 is formed by, for example, MBE (Molecular Beam Epitaxy) method, MOCVD (Metal Organic Chemical Vapor Deposition), or organic. It is formed by epitaxial crystal growth by a metal chemical vapor deposition method. At this time, for example, trimethylaluminum (TMA), trimethylgallium (TMG), trimethylindium (TMIn), or arsine (AsH ₃ ) is used as a raw material for a GaAs-based compound semiconductor. Hydrogen selenide (H ₂ Se) is used, and dimethyl zinc (DMZ), for example, is used as the acceptor impurity raw material.

  First, the lower clad layer 11, the active layer 12, the upper clad layer 13, the oxidized layer 14D, the upper DBR layer 15 and the contact layer 16 are formed on one surface of the substrate 10 by using an epitaxial crystal growth method. The layers are stacked in this order (FIG. 3A).

  Next, a circular resist layer (not shown) is formed on the contact layer 16. Subsequently, the mesa portion 17 is formed by selectively etching from the contact layer 16 to the lower cladding layer 11 by using, for example, reactive ion etching (RIE), using the resist layer as a mask (FIG. 3). (B)). Thereafter, the resist layer is removed.

  Next, an oxidation treatment is performed at a high temperature in a water vapor atmosphere to selectively oxidize Al of the layer to be oxidized from the side surface of the mesa portion 17. As a result, the outer edge region of the oxidized layer becomes the current confinement region 14A, and the central region becomes the current injection region 14A (FIG. 4A).

  Next, the lower DBR layer 18 is formed on the other surface of the substrate 10 by film formation using an epitaxial crystal growth method, a CVD (Chemical Vapor Deposition) method, or a sputtering method (FIG. 4B). Thereafter, the upper electrode 20 is formed on the contact layer 18 by, for example, vapor deposition, and the lower electrode 21 is formed on the surface of the lower DBR layer 18. In this way, the semiconductor laser 1 of the present embodiment is manufactured.

  Next, the operation and effect of the semiconductor laser 1 of the present embodiment will be described.

  In the semiconductor laser 1 of the present embodiment, when a predetermined voltage is applied between the upper electrode 20 and the lower electrode 21, the current confined by the current confinement layer 14 is injected into the active layer 12, thereby Light emission occurs due to recombination of electrons and holes. This light is reflected by the pair of lower DBR layer 18 and upper DBR layer 15, causes laser oscillation at a predetermined wavelength, and is emitted to the outside as a laser beam.

  Incidentally, in the present embodiment, the substrate 10 is provided between the lower DBR layer 18 and the lower cladding layer 11, that is, in the cavity. As a result, the effective resonator length of the semiconductor laser 1 is increased by the thickness of the substrate 10, so that a plurality of axial modes (for example, λx1, λx2, and λx3 as shown in FIG. 2B). Oscillation occurs in three axis modes).

Thereby, even if the difference Δλ (wavelength offset amount) between the effective resonator length λx and the emission wavelength λy of the active layer 12 changes due to temperature change, one axial mode among the plurality of axial modes. , The wavelength offset amount is equal to or close to the wavelength offset amount (Δλ ₀ described above) when the optical output is maximized.

Here, the interval λ _FSR of the axial mode can be expressed by the following equation.
λ _FSR = λ ₀ ² / (2n _r L)

Here, λ ₀ is the oscillation wavelength. n _r is the effective refractive index. L is the resonator length.

From the above equation, it can be seen that when the resonator length is on the order of the thickness of the substrate 10, the axial mode interval λ _FSR is extremely narrow. Therefore, even if the oscillation wavelength is shifted due to a temperature change, the wavelength offset amount at the oscillation wavelength after the shift is equal to the wavelength offset amount (Δλm) when the optical output becomes maximum in any of the axial modes. Or close to that. Accordingly, since the magnitude of the light output does not change much due to the temperature change, the temperature dependence of the light output can be reduced compared to the case where the substrate 10 is not provided in the cavity.

  In this embodiment, since oscillation occurs in a plurality of axial modes, it is resistant to return light as in the case where the transverse mode is changed to multimode. In other words, in this embodiment, it is not necessary to make the transverse mode multi-mode in order to make it strong against the return light. Therefore, even if the single transverse mode oscillation is performed using the method described later, strong. Further, in this embodiment mode, it is not necessary to enlarge the light emitting region of the active layer in order to make it strong against the return light, so that it can be operated with a low threshold current.

  In the present embodiment, since the substrate 10 is provided between the lower DBR layer 18 and the lower cladding layer 11, that is, in the cavity, the substrate 10 is close to the active layer 12 that is a heat source. Therefore, heat dissipation is higher than that of a conventional semiconductor laser in which a lower DBR layer, a lower cladding layer, an active layer, an upper cladding layer, and an upper DBR layer are stacked on a substrate. Therefore, the maximum output can be increased as compared with the conventional type semiconductor laser without increasing the current injection amount.

  In the present embodiment, in order to increase the effective resonator length of the semiconductor laser 1, the substrate 10 is provided in the cavity. Thereby, for example, instead of providing the substrate 10 in the cavity, the semiconductor laser is manufactured in comparison with the case where the semiconductor layer for increasing the effective resonator length of the semiconductor laser 1 is formed by epitaxial crystal growth. The time and cost required can be greatly reduced.

[Modification]
In the above embodiment, the lower DBR layer 18 is formed on the entire back surface of the substrate 10. However, the lower DBR layer 18 may be formed only in a region facing the mesa portion 17 on the back surface of the substrate 10. For example, as shown in FIGS. 5A and 5B, the lower DBR layer 18 is a cylindrical mesa portion 22 extending in the stacking direction, and the central axis AX1 of the mesa portion 22 is the center of the mesa portion 17. The mesa unit 22 can be arranged so as to be on the axis AX2. At this time, the diameter W1 of the mesa portion 22 is equal to or smaller than the diameter W2 of the mesa portion 17. For this reason, the beam traveling from the active layer 12 to the mesa portion 22 side spreads due to the long resonator length, so that the outer edge portion of the beam traveling from the active layer 12 to the mesa portion 22 side, that is, a higher-order transverse mode The dominant part cannot enter the mesa part 22. As a result, the fundamental transverse mode of the beam traveling from the active layer 12 to the mesa portion 22 side is mainly reflected by the lower DBR layer 18, so that fundamental transverse mode oscillation is generated while suppressing higher-order transverse mode oscillation. Can do. Therefore, in this modification, it is possible to achieve both suppression of higher-order transverse mode oscillation and higher output.

  In the above modification, instead of making the shape of the mesa portion 17 cylindrical, for example, as shown in FIGS. 6A and 6B, the mesa portion 17 extends in the stacking direction and is orthogonal to the stacking direction. It is also possible to use a flat columnar shape extending in the direction. At this time, as shown in FIGS. 6A and 6B, the length of the mesa portion 22 in the longitudinal direction is equal to or smaller than the diameter W2 of the mesa portion 17, and the mesa portion is further reduced. When the length in the short direction of 22 is smaller than the length in the longitudinal direction of the mesa portion 22, not only the suppression of higher-order transverse mode oscillation but also the deflection direction is fixed to the longitudinal direction of the mesa portion 22. It is also possible to perform control.

  Moreover, in the said embodiment and the said modification, although the board | substrate 10 has been arrange | positioned between the lower DBR layer 18 and the lower clad layer 11, for example, FIG. 7, FIG. 8 (A), (B), FIG. 9 (A) and 9 (B), it is also possible to dispose inside the lower DBR layer 18.

  Such a semiconductor laser 1 can be manufactured, for example, as follows. First, a part of the lower DBR layer 18 (first lower multilayer reflector), the lower cladding layer 11, the active layer 12, and the upper cladding are formed on one surface of the substrate 10 by deposition using an epitaxial crystal growth method. The layer 13, the oxidized layer 14D, the upper DBR layer 15, and the contact layer 16 are stacked in this order (FIG. 10A).

  Next, a circular resist layer (not shown) is formed on the contact layer 16. Subsequently, the mesa portion 17 is formed by selectively etching from the contact layer 16 to the lower cladding layer 11 by using, for example, the RIE method using the resist layer as a mask (FIG. 10B). Thereafter, the resist layer is removed.

  Next, an oxidation treatment is performed at a high temperature in a water vapor atmosphere to selectively oxidize Al of the layer to be oxidized from the side surface of the mesa portion 17. Thus, the outer edge region of the oxidized layer becomes the current confinement region 14A, and the central region becomes the current injection region 14A (FIG. 11A).

  Next, the remaining portion of the lower DBR layer 18 (second lower multilayer reflector) is formed on the other surface of the substrate 10 by film formation using an epitaxial crystal growth method, a CVD method, or a sputtering method (FIG. 2). 11 (B)). Thereafter, the upper electrode 20 is formed on the contact layer 18 by, for example, vapor deposition, and the lower electrode 21 is formed on the surface of the lower DBR layer 18. In this way, the semiconductor laser 1 according to this modification is manufactured.

  In the semiconductor laser 1 according to this modification, since the substrate 10 is disposed inside the lower DBR layer 18, a part of the lower DBR layer 18 exists in the vicinity of the active layer 12. As a result, light can be efficiently confined in a part of the lower DBR layer 18, and oscillation can be performed with a small amount of injected current.

[Second Embodiment]
FIG. 12 shows an example of a cross-sectional configuration of the semiconductor laser 2 according to the second embodiment of the present invention. Note that FIG. 12 is a schematic representation, which differs from actual dimensions and shapes. Similar to the semiconductor laser 1 of the first embodiment, the semiconductor laser 2 is a surface emitting semiconductor laser that emits light in the stacking direction, and has a stacked structure on both surfaces of the substrate 30. However, the semiconductor laser 2 includes a current injection portion 35 made of a non-oxidized transparent conductive film such as ITO (Indium Tin Oxide) instead of the current confinement layer 14 formed by oxidation. For example, it can be suitably applied to a GaN-based semiconductor.

  For example, as shown in FIG. 12, the semiconductor laser 2 includes a lower clad layer 31, an active layer 32, an upper clad layer 33, a current injection part 35, and an upper DBR layer 36 on one surface of the substrate 30. The lower DBR layer 39 is provided on the other surface of the substrate 30 (on the surface opposite to the lower cladding layer 31). In other words, the semiconductor laser 2 is provided with the substrate 30 between a pair of resonator mirrors constituted by the upper DBR layer 36 and the lower DBR layer 39, that is, in the cavity, and has a plurality of axial modes (for example, As shown in FIG. 2B, oscillation is possible at three wavelengths (λx1, λx2, λx3).

  A mesa portion 37 extending in the stacking direction is formed in the upper portion of the stacked structure in the semiconductor laser 2, specifically, in the upper DBR layer 36. The mesa portion 37 has a cylindrical shape with a width of about 20 μm, for example. Further, the side of the current injection part 35 immediately below the mesa part 37 is covered with the upper electrode 34, and is provided in the opening 34 </ b> A of the upper electrode 34. An insulating layer 38 is provided on the upper surface of the upper electrode 34. On the other hand, the lower portion of the stacked structure in the semiconductor laser 2, specifically, the lower DBR layer 39 is formed, for example, at least in a region facing the mesa portion 37, for example, over the entire back surface of the substrate 30. ing. A lower electrode 40 is provided on the bottom surface of the lower DBR layer 39.

  In the present embodiment, the lower DBR layer 39 corresponds to a specific example of the “lower multilayer reflector” of the present invention, and the upper DBR layer 36 is a specific example of the “upper multilayer reflector” of the present invention. The substrate 30 corresponds to a specific example of the “semiconductor substrate” of the present invention.

  The substrate 30 corresponds to the lowermost layer (substrate) for film formation (for example, epitaxial crystal growth and deposition), and is, for example, an n-type GaN substrate. The thickness of the substrate 30 is, for example, a value within the range of 100 μm or more and 600 μm or less. Examples of the n-type impurity include silicon (Si) and selenium (Se).

The lower cladding layer 31 is made of a GaN-based material such as n-type In _x10 Ga _1-x10 N (0 ≦ x10 <1). The upper cladding layer 33 is made of a GaN-based material such as p-type In _x11 Ga _1-x11 N (0 ≦ x11 <1). Examples of the p-type impurity include zinc (Zn), magnesium (Mg), and beryllium (Be).

The active layer 32 is made of a material having a band gap corresponding to a wavelength band that is difficult to be absorbed by the substrate 30 (for example, a GaN-based material). The active layer 32 has, for example, an undoped In _x12 Ga _1-x12 N / GaN quantum well structure (0 <x12 <1). For example, as shown in FIGS. 2A and 2B, the active layer 32 has one oscillation wavelength (for example, λ ₁ , λ ₂ , λ ₃ ) at 25 ° C. For example, it is made of a material that has a maximum gain (for example, gain at a position indicated by P1 in FIG. 2A) at 25 ° C. at λ ₁ . More specifically, the active layer 32 includes, for example, a plurality of oscillation wavelengths (for example, λ ₁ , λ ₂ , λ ₃ ) at 25 ° C. as shown in FIGS. The difference Δλa (= λ ₁ −λ ₄ ) between one oscillation wavelength (for example, λ ₁ ) and the emission wavelength λ ₄ corresponding to the band gap of the active layer 12 at 25 ° C. is Δλm (when the maximum gain is reached). , And is made of a material that is equal to the oscillation wavelength λx and the emission wavelength λy (difference between <λx). For example, when the active layer 32 has an undoped In _x12 Ga _1-x12 N / GaN quantum well structure, the In composition ratio x12 has a plurality of oscillation wavelengths at 25 ° C. (for example, λ ₁ , λ ₂ , Λ ₃ ) at one oscillation wavelength (for example, λ ₁ ), it is equal to a value that gives a maximum gain at 25 ° C.

Here, the fluctuation amount with respect to the temperature change of the oscillation wavelength λx and the fluctuation amount with respect to the temperature change of the emission wavelength λy are different from each other, and the fluctuation amount with respect to the temperature change of the emission wavelength λy is different. Bigger than. Therefore, the difference Δλ (= λx−λy) between the oscillation wavelength λx and the emission wavelength λy becomes smaller as the temperature rises. Therefore, when the active layer 32 is made of a material such that Δλa is equal to Δλm, the temperature at which the difference Δλx2 between the oscillation wavelength λx2 and the emission wavelength λy becomes Δλm is higher than 25 ° C. (for example, The temperature at which the difference Δλx3 between the oscillation wavelength λx3 and the emission wavelength λy becomes Δλm exists on the higher temperature side (for example, 60 ° C). In FIG. 2B, the difference Δλa at 25 ° C. is Δλm, and one oscillation wavelength (for example, λ ₅ , λ ₆ , λ ₇ ) at 40 ° C. For example, the difference Δλb (= λ ₆ −λ ₈ ) between λ ₆ ) and the emission wavelength λ ₈ corresponding to the band gap of the active layer 12 at 40 ° C. is Δλm, and a plurality of oscillations at 60 ° C. wavelength _{(e.g., λ 9, λ 10, λ} 11) as one of the oscillation wavelength of the (e.g., lambda _11), the difference Δλc the emission wavelength lambda ₁₂ corresponding to the band gap at 60 ° C. of the active layer 12 (= lambda ₁₁ -λ ₁₂ ) is illustrated as Δλm.

In general, it is known that the gain of the surface emitting semiconductor laser is maximized when the difference Δλ between the oscillation wavelength λx and the emission wavelength λy corresponding to the band gap of the active layer has a predetermined magnitude. For example, when the active layer 12 has an In _x12 Ga _1-x12 N / GaN quantum well structure, the gain of the surface emitting semiconductor laser is maximized when Δλm is 10 nm.

  The current injection portion 34 is provided in a portion immediately below the central region of the mesa portion 37 and has, for example, a disk shape. As described above, the current injection portion 34 is configured by a non-oxidized transparent conductive film such as ITO. Accordingly, a region of the active layer 32 that faces the current injection portion 34 corresponds to the current injection region of the active layer 32, that is, the light emitting region 32A.

The upper DBR layer 36 has a laminated structure in which, for example, a low refractive index layer (not shown) and a high refractive index layer (not shown) are alternately laminated, and the uppermost layer has a high refractive index. ing. The low refractive index layer is made of, for example, a dielectric film (eg, SiO ₂ ) having a thickness of λ ₁ / 4n ₁ , and the high refractive index layer is made of, for example, a dielectric film (Ta ₂ O having a thickness of λ ₁ / 4n ₂ ). ₅ ). Here, n ₁ is the refractive index of the low refractive index layer. n _{2 is a} refractive index of the high refractive index layer, and is larger than n ₂ .

The lower DBR layer 39 has, for example, a stacked structure in which low refractive index layers (not shown) and high refractive index layers (not shown) are alternately stacked. The low refractive index layer is made of, for example, a dielectric film (eg, SiO ₂ ) having a thickness of λ ₁ / 4n ₃ , and the high refractive index layer is made of, for example, a dielectric film (Ta _{2 having a} thickness of λ ₁ / 4n ₄ ). O ₅ ). Here, n ₃ is the refractive index of the low refractive index layer. n ₄ is the refractive index of the high refractive index layer, and is larger than n ₃ .

Incidentally, on the low refractive index layers and high refractive index layers in the upper DBR layer 36 and the lower DBR layer 39 is not limited to the above configuration, for example, it kept its optical thickness lambda _1/4, You may be comprised by multiple layers. The stacked at least one of the upper DBR layer 36 and the lower DBR layer 39 may be formed of a material other than the dielectric, for example, alternating different semiconductor layers having a refractive index in the optical thickness lambda _1/4 It may be configured as. In the case where the lower DBR layer 39 is made of a dielectric material, in order to ensure conduction between the lower electrode 40 and the substrate 30, a part of the lower DBR layer 39 is removed and the substrate 30 is removed. It is preferable to expose the surface of the substrate and to form the lower electrode 40 on the exposed surface.

  The upper electrode 20 has a structure in which, for example, titanium (Ti), platinum (Pt), and gold (Au) are stacked in this order from the substrate 30 side, and is electrically connected to the upper cladding layer 33. The lower electrode 40 has a structure in which, for example, an alloy of gold (Au) and germanium (Ge), nickel (Ni), and gold (Au) are stacked in this order from the substrate 30 side. It is connected to the.

  The semiconductor laser 2 according to the present embodiment can be manufactured as follows, for example.

For example, in order to manufacture a GaN-based surface emitting semiconductor laser, for example, a stacked structure on the substrate 30 and the substrate 50 is formed by, for example, MBE (Molecular Beam Epitaxy) method, MOCVD (Metal Organic Chemical Vapor). It is formed by epitaxial crystal growth by Deposition (metal organic chemical vapor deposition) method. At this time, for example, trimethylaluminum (TMA), trimethylgallium (TMG), trimethylindium (TMIn), or ammonia (NH3) is used as a raw material for a GaN-based compound semiconductor. Hydrogen halide (H ₂ Se) is used, and dimethyl zinc (DMZ), for example, is used as the acceptor impurity raw material.

  First, the upper DBR layer 36 is stacked on one surface of the substrate 50 by film formation using an epitaxial crystal growth method (FIG. 13A). Next, a circular resist layer (not shown) is formed on the upper DBR layer 36. Subsequently, the mesa portion 37 is formed by selectively etching the upper DBR layer 36 by using, for example, a reactive ion etching method using the resist layer as a mask (FIG. 13B). Thereafter, the resist layer is removed.

  Next, after the lower clad layer 31, the active layer 32, and the upper clad layer 33 are laminated in this order on one surface of the substrate 30 by film formation using an epitaxial crystal growth method, a predetermined on the upper clad layer 33 is formed. The upper electrode 34 having the opening 34A is formed at the position, and the current injection portion 35 is formed inside the opening 34A (FIG. 14A).

  Next, the lower DBR layer 39 is formed on the other surface of the substrate 10 by film formation using an epitaxial crystal growth method, a CVD method, or a sputtering method (FIG. 14B). Thereafter, the lower electrode 40 is formed on the lower DBR layer 39 by, for example, vapor deposition.

  Next, after bonding the substrate 50 to the current injection portion 35 on the substrate 30 with the mesa portion 37 facing down (FIG. 15A), the substrate 50 is removed (FIG. 15B). In this way, the semiconductor laser 2 of the present embodiment is manufactured.

  Next, the operation and effect of the semiconductor laser 2 of the present embodiment will be described.

  In the semiconductor laser 2 of the present embodiment, when a predetermined voltage is applied between the upper electrode 34 and the lower electrode 40, a current is injected into the active layer 32 via the current injection portion 35, whereby electrons and Light emission occurs due to recombination of holes. This light is reflected by the pair of lower DBR layer 39 and upper DBR layer 36, causes laser oscillation at a predetermined wavelength, and is emitted to the outside as a laser beam.

  By the way, in the present embodiment, the substrate 30 is provided between the lower DBR layer 39 and the lower cladding layer 31, that is, in the cavity. As a result, the effective resonator length of the semiconductor laser 2 is increased by the thickness of the substrate 30, so that a plurality of axial modes (for example, λx1, λx2, λx3 as shown in FIG. 2B). Oscillation occurs in three axis modes).

Thereby, even if the difference Δλ (wavelength offset amount) between the effective resonator length λx and the emission wavelength λy of the active layer 32 changes due to temperature change, one axial mode among the plurality of axial modes. , The wavelength offset amount is equal to or close to the wavelength offset amount (Δλ ₀ described above) when the optical output is maximized.

From the equation of the axial mode interval λ _FSR shown in the above embodiment, it can be seen that the axial mode interval λ _FSR is extremely narrow when the resonator length is on the order of the thickness of the substrate 30. Therefore, even when the oscillation wavelength is shifted due to a temperature change, the wavelength offset amount at the oscillation wavelength after the shift in any of the axial modes is the wavelength offset amount (Δλm) when the optical output is maximized. It is equal to or close to it. Accordingly, since the magnitude of the light output does not change much due to the temperature change, the temperature dependence of the light output can be reduced as compared with the case where the substrate 30 is not provided in the cavity.

  In this embodiment, since oscillation occurs in a plurality of axial modes, it is resistant to return light as in the case where the transverse mode is changed to multimode. In other words, in this embodiment, it is not necessary to make the transverse mode multi-mode in order to make it strong against the return light. Therefore, even if the single transverse mode oscillation is performed using the method described later, strong. Further, in this embodiment mode, it is not necessary to enlarge the light emitting region of the active layer in order to make it strong against the return light, so that it can be operated with a low threshold current.

  In the present embodiment, since the substrate 30 is provided between the lower DBR layer 39 and the lower cladding layer 31, that is, in the cavity, the substrate 30 is close to the active layer 32 that is a heat source. Therefore, heat dissipation is higher than that of a conventional semiconductor laser in which a lower DBR layer, a lower cladding layer, an active layer, an upper cladding layer, and an upper DBR layer are stacked on a substrate. Therefore, the maximum output can be increased as compared with the conventional type semiconductor laser without increasing the current injection amount.

  In the present embodiment, the substrate 30 is provided in the cavity in order to increase the effective resonator length of the semiconductor laser 2. Thereby, for example, instead of providing the substrate 30 in the cavity, compared with the case where a semiconductor layer for increasing the effective resonator length of the semiconductor laser 2 is formed by epitaxial crystal growth, the semiconductor laser is manufactured. The time and cost required can be greatly reduced.

[Modification]
In the above embodiment, the lower DBR layer 39 is formed on the entire back surface of the substrate 30. However, the lower DBR layer 39 may be formed only in a region facing the mesa portion 37 on the back surface of the substrate 30. For example, as shown in FIGS. 16A and 16B, the lower DBR layer 39 is a cylindrical mesa portion 41 extending in the stacking direction, and the central axis AX1 of the mesa portion 41 is the center of the mesa portion 37. The mesa unit 41 can be arranged so as to be on the axis AX2. At this time, the diameter W3 of the mesa portion 41 is equal to or smaller than the diameter W4 of the mesa portion 37. For this reason, the beam traveling from the active layer 32 to the mesa unit 41 side spreads due to the long resonator length, and therefore, the outer edge portion of the beam traveling from the active layer 32 to the mesa unit 41 side, that is, a higher-order transverse mode The dominant part cannot enter the mesa part 41. As a result, the fundamental transverse mode of the beam traveling from the active layer 32 to the mesa portion 41 side is mainly reflected by the lower DBR layer 39, so that fundamental transverse mode oscillation is generated while suppressing higher-order transverse mode oscillation. Can do. Therefore, in this modification, it is possible to achieve both suppression of higher-order transverse mode oscillation and higher output.

  In the above modification, instead of making the shape of the mesa portion 41 cylindrical, for example, as shown in FIGS. 17A and 17B, the mesa portion 41 extends in the stacking direction and is orthogonal to the stacking direction. It is also possible to use a flat columnar shape extending in the direction. At this time, as shown in FIGS. 17A and 17B, the length of the mesa portion 41 in the longitudinal direction is made equal to or smaller than the diameter W4 of the mesa portion 37, and further, the mesa portion is further reduced. When the length in the short direction of 41 is made smaller than the length in the longitudinal direction of the mesa portion 41, not only suppression of higher-order transverse mode oscillation but also deflection for fixing the deflection direction in the longitudinal direction of the mesa portion 41 It is also possible to perform control.

  Moreover, in the said embodiment and the said modification, although the board | substrate 30 was arrange | positioned between the lower DBR layer 39 and the lower clad layer 31, for example, FIG. 18, FIG. 19 (A), (B), FIG. As shown in FIGS. 20 (A) and 20 (B), it can be arranged inside the lower DBR layer 18.

  Such a semiconductor laser 2 can be manufactured as follows, for example. First, the upper DBR layer 36 is stacked on one surface of the substrate 50 by film formation using an epitaxial crystal growth method. Next, a circular resist layer is formed on the upper DBR layer 36. Subsequently, the mesa portion 37 is formed by selectively etching the upper DBR layer 36 by, for example, reactive ion etching using the resist layer as a mask. Thereafter, the resist layer is removed.

  Next, a part of the lower DBR layer 39 (first lower multilayer reflector), the lower cladding layer 31, the active layer 32, and the upper portion are formed on one surface of the substrate 30 by film formation using an epitaxial crystal growth method. After laminating the clad layer 33 in this order, an upper electrode 34 having an opening 34A is formed at a predetermined position on the upper clad layer 33, and a current injection portion 35 is formed inside the opening 34A.

  Next, the remaining portion of the lower DBR layer 39 (second lower multilayer reflector) is formed on the other surface of the substrate 30 by film formation using an epitaxial crystal growth method, a CVD method, or a sputtering method. Thereafter, the lower electrode 40 is formed on the surface of the lower DBR layer 39, for example, by vapor deposition.

  Next, after the substrate 50 is bonded to the current injection portion 35 on the substrate 30 with the mesa portion 37 facing down, the substrate 50 is removed. In this way, the semiconductor laser 2 of this modification is manufactured.

  In the semiconductor laser 2 according to this modification, the substrate 30 is disposed inside the lower DBR layer 39, so that a part of the lower DBR layer 39 exists in the vicinity of the active layer 3. As a result, light can be efficiently confined in a part of the lower DBR layer 39, so that it is possible to oscillate with a small injection current amount.

  While the present invention has been described with reference to the embodiment and its modifications, the present invention is not limited to the above-described embodiment and the like, and various modifications can be made.

  For example, in the above-described embodiment and the like, an n-type semiconductor substrate is used as the substrate of the semiconductor lasers 1 and 2, but a p-type semiconductor substrate may be used. However, in that case, in the description of each semiconductor layer in the above embodiment and the like, p-type is read as n-type and n-type is read as p-type.

  The present invention is naturally applicable not only to a semiconductor laser but also to a light emitting diode.

1 is a cross-sectional view of a semiconductor laser according to a first embodiment of the present invention. FIG. 2 is a characteristic diagram showing temperature dependence of gain and wavelength of the semiconductor laser of FIG. 1. FIG. 7 is a cross-sectional view for explaining an example of a manufacturing process of the semiconductor laser of FIG. It is sectional drawing for demonstrating the process following FIG. FIG. 6 is a cross-sectional view illustrating a modification of the semiconductor laser in FIG. 1. FIG. 10 is a cross-sectional view illustrating another modification of the semiconductor laser in FIG. 1. FIG. 10 is a cross-sectional view illustrating another modification of the semiconductor laser in FIG. 1. FIG. 6 is a cross-sectional view illustrating a modification of the semiconductor laser in FIG. 5. FIG. 7 is a cross-sectional view illustrating a modification of the semiconductor laser in FIG. 6. FIG. 8 is a cross-sectional view for explaining an example of a manufacturing process of the semiconductor laser of FIG. It is sectional drawing for demonstrating the process following FIG. It is sectional drawing of the semiconductor laser in the 2nd Embodiment of this invention. FIG. 13 is a cross-sectional view for explaining an example of a manufacturing process of the semiconductor laser of FIG. It is sectional drawing for demonstrating the process following FIG. It is sectional drawing for demonstrating the process following FIG. FIG. 13 is a cross-sectional view illustrating a modification of the semiconductor laser in FIG. 12. FIG. 14 is a cross-sectional view illustrating another modification of the semiconductor laser in FIG. 12. FIG. 13 is a cross-sectional view illustrating another modification of the semiconductor laser in FIG. 12. FIG. 17 is a cross-sectional view illustrating a modification of the semiconductor laser in FIG. 16. FIG. 18 is a cross-sectional view illustrating a modification of the semiconductor laser in FIG. 17. It is the characteristic view showing the temperature dependence of the gain and wavelength of the conventional semiconductor laser.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,2 ... Semiconductor laser, 10, 30 ... Substrate, 11, 31 ... Lower clad layer, 12, 32 ... Active layer, 12A, 32A ... Light emitting region, 13, 33 ... Upper clad layer, 14 ... Current confinement layer, 14A ... current confinement region, 14B ... current injection region, 15, 36 ... upper DBR layer, 16 ... contact layer, 17, 22, 37, 41 ... mesa portion, 18, 39 ... lower DBR layer, 19, 38 ... insulating layer, 20, 34 ... upper electrode, 21, 40 ... lower electrode, 34A ... opening, 35 ... current injection part.

Claims (20)

  A semiconductor layer including a lower clad layer, an active layer, an upper clad layer, and an upper multilayer reflector in order is formed on one surface of the semiconductor substrate, and the lower multilayer reflector is formed on the other surface of the semiconductor substrate. The manufacturing method of the semiconductor light-emitting device which forms.   The method for manufacturing a semiconductor light emitting element according to claim 1, wherein the semiconductor layer is formed by at least one of film formation and bonding.   The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein the lower multilayer-film reflective mirror is formed by film formation or bonding.   A semiconductor layer including a first lower multilayer reflector, a lower clad layer, an active layer, an upper clad layer and an upper multilayer reflector in order is formed on one surface of the semiconductor substrate, and the other surface of the semiconductor substrate is formed. A method for manufacturing a semiconductor light emitting device, wherein a second lower multilayer film reflecting mirror is formed thereon.   The method for manufacturing a semiconductor light-emitting element according to claim 4, wherein the semiconductor layer is formed by at least one of film formation and bonding.   The method for manufacturing a semiconductor light-emitting element according to claim 4, wherein the lower multilayer-film reflective mirror is formed by film formation or bonding.   A lower multilayer reflector, a lower clad layer, an active layer, an upper clad layer, and an upper multilayer reflector are provided in this order, and the inside of the lower multilayer reflector or between the lower multilayer reflector and the lower clad layer. A semiconductor light emitting device comprising a semiconductor substrate. The semiconductor substrate is disposed between the lower multilayer reflector and the lower cladding layer,
The lower clad layer, the active layer, the upper clad layer, and the upper multilayer reflector are formed on one surface of the semiconductor substrate by film formation or bonding. 8. The semiconductor light emitting device according to 7. The semiconductor substrate is disposed between the lower multilayer reflector and the lower cladding layer,
8. The semiconductor light emitting device according to claim 7, wherein the lower multilayer reflector is formed by depositing or bonding on a surface of the semiconductor substrate opposite to the lower cladding layer. element. The semiconductor substrate is disposed between the lower multilayer reflector and the lower cladding layer,
The semiconductor layer including at least the lower clad layer, the active layer, the upper clad layer, and the upper multilayer reflector has a cylindrical shape extending in the stacking direction,
The semiconductor light-emitting element according to claim 7, wherein the lower multilayer-film reflective mirror has a cylindrical shape extending in the stacking direction, and the diameter thereof is equal to or smaller than the diameter of the semiconductor layer. The semiconductor substrate is disposed between the lower multilayer reflector and the lower cladding layer,
The semiconductor layer including at least the lower clad layer, the active layer, the upper clad layer, and the upper multilayer reflector has a cylindrical shape extending in the stacking direction,
The semiconductor light-emitting element according to claim 7, wherein the lower multilayer-film reflective mirror has a flat columnar shape that extends in the stacking direction and extends in one direction orthogonal to the stacking direction. The semiconductor substrate is disposed between the lower multilayer reflector and the lower cladding layer,
The semiconductor light emitting element according to claim 7, wherein the lower multilayer film reflecting mirror is formed by alternately laminating dielectric films having different refractive indexes. The semiconductor substrate is disposed between the lower multilayer reflector and the lower cladding layer,
The semiconductor light emitting device according to claim 7, wherein the semiconductor substrate, the lower cladding layer, the active layer, the upper cladding layer, and the upper multilayer reflector are made of a GaN-based material. The semiconductor substrate is disposed inside the lower multilayer reflector,
A part of the lower multilayer reflector, the lower clad layer, the active layer, the upper clad layer, and the upper multilayer reflector are formed on or bonded to one surface of the semiconductor substrate. 8. The semiconductor light emitting device according to claim 7, wherein the semiconductor light emitting device is formed. The semiconductor substrate is disposed inside the lower multilayer reflector,
A portion of the lower multilayer reflector other than the portion formed on one surface side of the semiconductor substrate is formed on the surface of the semiconductor substrate opposite to the lower cladding layer, or 8. The semiconductor light emitting device according to claim 7, wherein the semiconductor light emitting device is formed by bonding. The semiconductor substrate is disposed inside the lower multilayer reflector,
The semiconductor layer including at least the lower clad layer, the active layer, the upper clad layer, and the upper multilayer reflector has a cylindrical shape extending in the stacking direction,
Of the lower multilayer mirror, the portion other than the portion formed on one surface side of the semiconductor substrate has a cylindrical shape extending in the stacking direction, and the diameter thereof is equal to the diameter of the semiconductor layer, The semiconductor light-emitting device according to claim 7, which is smaller than that. The semiconductor substrate is disposed inside the lower multilayer reflector,
The semiconductor layer including at least the lower clad layer, the active layer, the upper clad layer, and the upper multilayer reflector has a cylindrical shape extending in the stacking direction,
Of the lower multilayer mirror, the portion other than the portion formed on one surface side of the semiconductor substrate has a flat columnar shape extending in the stacking direction and extending in one direction orthogonal to the stacking direction. The semiconductor light emitting device according to claim 7. The semiconductor substrate is disposed inside the lower multilayer reflector,
8. The semiconductor light emitting element according to claim 7, wherein portions other than the portion formed on one surface side of the semiconductor substrate in the lower multilayer film reflecting mirror are alternately laminated with dielectric films having different refractive indexes. The semiconductor substrate is disposed inside the lower multilayer reflector,
Of the lower multilayer reflector, a portion formed on one surface side of the semiconductor substrate, the semiconductor substrate, the lower clad layer, the active layer, the upper clad layer, and the upper multilayer reflector are GaN-based materials. The semiconductor light-emitting device according to claim 7.   The semiconductor light emitting device according to claim 7, wherein the semiconductor substrate has a thickness of 100 μm or more.

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