TWI671260B - Patterned photovoltaic substrate with improved luminous efficiency, light emitting diode and manufacturing method thereof - Google Patents

Abstract

The present invention discloses a patterned photovoltaic substrate, a light-emitting diode, and a manufacturing method thereof with enhanced luminous efficiency. The manufacturing method includes providing a substrate; forming a first patterned structure and a space region on the substrate surface; and forming a first A metal layer and a second metal layer; forming a second patterned structure on the second metal layer; extending the second patterned structure down to a portion of the surface of the first metal layer and the substrate; removing the first from the substrate The metal layer and the second metal layer form a substrate having a first patterned structure and a second patterned structure; a filling layer is formed at a predetermined growth rate to fill the second patterned structure.

Description

Patterned photovoltaic substrate with improved luminous efficiency, light emitting diode and manufacturing method thereof

The present invention relates to a patterned photovoltaic substrate, a light-emitting diode and a manufacturing method thereof with improved luminous efficiency, and more particularly to a substrate having both a micron-level first pattern structure and a sub-micron-level second patterned structure, and A light emitting diode of the substrate is provided with a filling layer in the second patterned structure and the second patterned structure is filled in order to improve the light emitting efficiency of the light emitting diode.

The historical development of human lighting has entered the era of solid-state lighting. Brighter brightness, lower prices, longer life, higher stability, etc. are the common goals pursued by the solid-state lighting industry. In the lighting market, the brightness requirements of light-emitting diodes are the first. In general, the maximum light output (L _max ) of a light-emitting diode is mainly determined by the external quantum efficiency (η _ext ) and the maximum operating current (I _max ), that is, L _max = η _ext × I _max , where the external quantum efficiency (η _ext ) is again determined by the internal quantum efficiency (η _int ) and the light extraction efficiency (η _extr ), that is, η _ext = η _int × η _extr . At present, the internal quantum efficiency of blue light-emitting diodes has generally reached more than 70%, but the internal quantum efficiency of green light-emitting diodes has suddenly dropped to less than 40%. Therefore, the internal quantum efficiency and light extraction efficiency have been improved to improve There is still much room for the external quantum efficiency of a light emitting diode or increasing the light emitting brightness of the light emitting diode.

Because the degree of lattice mismatch between GaN and sapphire substrate is as high as 16%, when using sapphire substrate as the substrate to perform epitaxial GaN thin film, there will be stress in the GaN thin film, and many different types will appear. Differential defect, which makes the differential discharge density of GaN film reach 10 ⁹ to 10 ¹⁰ cm ^-2 , which seriously affects the quality of the epitaxial film, and the defect usually acts as a non-radiative recombination center, resulting in a decrease in luminous efficiency. Therefore, the key to the development of patterned sapphire substrate manufacturing technology is to reduce the defect density in order to substantially improve the epitaxial quality of GaN thin films and increase the luminous brightness. By growing the GaN thin film on the sidewall of the pattern substrate to change the growth direction of the GaN thin film differential defect, the differential defect will be bent by 90 °, which will eliminate the defect by interlacing each other to form a stacking misalignment, and transmit three-dimensional stress during epitaxy. Releasing reduces the formation of defects and reduces the differential density within the film to improve crystal quality. Current research has also pointed out that the use of patterned sapphire substrates for the growth of GaN films has been found to reduce the density of differential defects to 10 ⁸ to 10 ⁹ cm ^-2 and further increase the internal quantum efficiency and luminous brightness of light-emitting diodes.

In the latest research, sub-micron-scale pattern substrates are also used to grow light-emitting diode structures. For pattern substrates of the same area, reducing the pattern size and increasing the number of patterns will increase the area of the effective area for lateral growth and enhance the lateral growth mechanism. As a result, it is easier to change the growth direction and form stacking misalignment to eliminate differential defects, and greatly reduce the internal differential density of the film. At the same time, due to the short pattern spacing, it is easy to form voids during the epitaxial growth of gallium nitride to prevent the extension of defects and improve the nitride. Epitaxial quality of gallium thin film. The research results show that the growth of gallium nitride films using micron-scale patterned sapphire substrates can reduce the differential density to 10 ⁸ cm ^-2 . If the pattern substrate is changed to sub-micron scale, the degree of stress release per unit volume can be increased. The differential row density is reduced to 10 ⁷ cm ^-2 or lower.

In the known technology, such as the Republic of China Publication Patent No. I396297, a light-emitting diode is disclosed, including: a substrate having micron-sized holes therein; and a nano-sized porous photonic crystal structure as a buffer layer formed on the substrate. The first type epitaxial layer is formed on the porous photonic crystal structure of the buffer layer; the light emitting layer is formed on the first type epitaxial layer; the second type epitaxial layer is formed on the light emitting layer; A first contact electrode is formed on the first type epitaxial layer; and a second contact electrode is formed on the second type epitaxial layer.

Another published patent of the Republic of China No. 201251113 discloses a method for manufacturing an LED substrate, an LED substrate, and a white LED structure. The main purpose is to make the LED emit high-brightness white light with good color rendering. The reflective surface of the substrate forms a plurality of numbers. The convex particles with curved surfaces on the top, the width of the bottom of these convex particles is 2 micrometers to 4 micrometers, the height of 1.2 micrometers to 1.8 micrometers, and the distance between adjacent convex particles is 0.6 micrometers to 3 micrometers. The indium gallium epitaxial layer emits ultraviolet light with a wavelength in the range of 380 to 410 nanometers after being energized. The ultraviolet light is reflected by the reflective surface of the substrate and the raised particles, and excites the mixed zinc oxide and yttrium aluminum garnet. Fluorescent substances generate complementary color light of ultraviolet light, and after mixing with each other, a package body scatters high-brightness white light with good color rendering, which can be used for lighting and other purposes.

However, in the above-mentioned inventive diodes, a nanometer-sized porous photonic crystal structure or micron-sized convex particles are mainly formed on the substrate to improve the luminous efficiency of the light-emitting diode. However, the micron-sized or The nano-level structural design still has its inherent limitations in reducing the degree of differential row density or increasing the degree of luminous efficiency.

In addition, as in the Republic of China Patent Application No. 102111662 filed by the applicant of the present application, a substrate for a photovoltaic element is disclosed, and at least one photovoltaic element is provided on an upper surface of the substrate, characterized in that the upper surface of the substrate has The plurality of micro-structures and the plurality of sub-micro-structures constitute a rough surface, wherein the sizes of the sub-micro structures are smaller than the micro-structures. In this way, the optical diffusion rate of the substrate can be improved, and the quality of the epitaxial thin film material grown on the substrate can be improved, thereby improving the light extraction efficiency of the photovoltaic element and achieving the luminous brightness of the entire photovoltaic element. The invention further provides a photovoltaic element. Among them, the previous case is a combination of micro-structure and sub-micro-structure proposed by the applicant of the present application to improve the quality of the epitaxial thin film material or the luminous brightness of the overall photovoltaic device.

Furthermore, during the process of covering the substrate with the epitaxial layer, if the pattern on the substrate includes a groove structure, the depth-to-width ratio of the groove has a corresponding relationship with the rate of the epitaxial layer. Further, if the groove has a high aspect ratio, that is, the groove has a deeper depth and a smaller width, the groove structure is easily unable to be completely completed by the epitaxial layer because the epitaxial layer has a faster epitaxial rate. Covering and filling; however, if the epitaxial rate is reduced in order to completely and completely fill the grooves with the epitaxial layer, the production efficiency will be reduced accordingly.

As mentioned above, when the epitaxial layer cannot completely cover the groove structure on the substrate, there will be a large number of gaps between the groove structure and the epitaxial layer. Further, since light enters different media, that is, the epitaxial layer enters the gap in the groove, the total reflection is increased. Therefore, the gap in the groove structure will make the LED travel direction of light from the light emitting layer. It is trapped in the groove structure by changing, resulting in poor light extraction efficiency, that is, reducing the light emitting efficiency of the light emitting diode.

Therefore, there is an urgent need to develop a patterned photovoltaic substrate with improved luminous efficiency and a light emitting diode with the substrate, which can effectively reduce and improve the light emitting efficiency of the light emitting diode, thereby improving the applicability and value of the light emitting diode. It really has its needs.

The main object of the present invention is to provide a patterned photovoltaic substrate with improved luminous efficiency and a method for manufacturing the same, which can fill the groove structure with a patterned structure and a filling layer on the surface of the substrate, thereby making the light emitting diodes The body has more stable and excellent luminous efficiency and performance.

To achieve the above object, the present invention provides a method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency. The steps include:

Step S1: providing a substrate;

Step S2: forming a first patterned structure and a space region on the surface of the substrate by a first etching process;

Step S3: forming a first metal layer and a second metal layer on the first patterned structure and the surface of the space region on the substrate;

Step S4: forming a second patterned structure on the second metal layer by a second etching process, the second patterned structure is located on one or both of the first patterned structure and the spaced region. By;

Step S5: the third patterned structure is extended downward to the first metal layer and a part of the surface of the substrate by a third etching process;

Step S6: removing the first metal layer and the second metal layer from the substrate by an acid solution to form the substrate having the first patterned structure and the second patterned structure;

And step S7: forming a filling layer to fill the second patterned structure at a predetermined growth rate.

The method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, wherein the shape of the structure of the second patterned structure is a micron-level groove structure, and its aspect ratio is between 0.3: 1 to 20: Between 1.

In the method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, the filling layer is filled in the second patterned structure by a physical vapor deposition method.

The method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, wherein the sub-micron-scale groove structure includes a polygonal structure.

The method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, wherein the predetermined growth rate is between 0.01 and 3.0 nanometers per second.

The method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, wherein a material used for the filling layer has a refractive index between 1.7 and 2.5.

A patterned photovoltaic substrate with improved luminous efficiency includes: a first patterned structure, which is a micron-scale protruding structure or a micron-scale groove structure; a space region; a second patterned structure, which is a micron Level groove structure formed on one or both of the first patterned structure and the space region; and a filling layer disposed in the sub-micron level groove structure of the second patterned structure.

The patterned photovoltaic substrate with improved luminous efficiency, wherein the first patterned structure or the second patterned structure is conical, arc-shaped, cylindrical, pyramid-shaped, or angular-pillar-shaped.

The patterned photovoltaic substrate with improved luminous efficiency, wherein the aspect ratio of the sub-micron groove structure is between 0.3: 1 and 20: 1.

In the patterned photovoltaic substrate with improved luminous efficiency, the filling layer is made of a material having a refractive index between 1.7 and 2.5.

A light emitting diode having a patterned photovoltaic substrate with improved luminous efficiency, comprising: a substrate, the substrate being the patterned photovoltaic substrate with improved luminous efficiency according to any one of the foregoing; a buffer layer provided on the substrate A substrate; and a photovoltaic element disposed on the buffer layer, and the photovoltaic element includes: a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, wherein the first semiconductor layer is bonded to the buffer layer The light emitting layer is sandwiched between the first semiconductor layer and the second semiconductor layer.

The light-emitting diode further includes a first electrode and a second electrode, and the first electrode and the second electrode are electrically connected to the first semiconductor layer and the second semiconductor layer, respectively.

The following is a description of specific embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied by other different specific embodiments, and various details in this specification can also be modified and changed for different viewpoints and applications without departing from the spirit of the present invention.

Please refer to FIG. 1 and FIGS. 2A to 2J, which is a method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, which includes the following steps:

Step S1: A substrate 10 is provided. In one embodiment, the substrate 10 is a sapphire substrate with a flat surface or a silicon substrate with a flat surface (see FIG. 2A).

Step S2: forming a first patterned structure 11 and a space region 12 on the surface of the substrate 10 by a first etching process (refer to FIG. 2B); in an embodiment, the first etching process may be an isotropic etching (Isotropic etching) or anisotropic etching, which can be inductively coupled plasma reactive ion etching (ICP-RIE), chemical liquid etching, dry etching, plasma etching, or lightning Shooting method. In addition, isotropic etching can use a chemical etching solution (such as a strong acid) to perform a chemical etching reaction under a high temperature environment to produce a micron-level protrusion or groove structure with a certain periodicity on the substrate 10; in addition, anisotropic The etching procedure is to first form a patterned photoresist layer on the substrate 10, and then use inductively coupled plasma reactive ion etching (ICP-RIE) technology to perform etching to selectively remove part of the substrate 10, which can also achieve the above. The purpose of forming a micron-scale protrusion or groove structure with a certain periodicity.

In addition, in step S2, it further includes providing a first photoresist layer (not shown) disposed on a part of the surface of the substrate 10, so that the first etching process can selectively remove part of the substrate 10; In the aforementioned method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, the first patterned structure 11 may be a micron-level protruding structure (as shown in FIG. 2B) or a micron-level groove structure, and the interval The region 12 may be a planar structure. In one aspect of the present invention, the first patterned structure 11 may be a one-micron-scale protruding structure having a height of 1.2 micrometers to 2 micrometers and an outer diameter of 1 micrometer to 5 micrometers. The distance between 11 (that is, the length or width of the interval region 12) is 0.1 micrometer to 1 micrometer. In addition, in another aspect of the present invention, the first patterned structure 11 may be a micron-level groove structure, which will be described in detail later.

Step S3: forming a first metal layer 13 and a second metal layer 14 on the surface of the first patterned structure 11 and the space region 12 on the substrate 10 (refer to FIG. 2C); wherein the first metal layer 13 or the second metal layer 13 14 can be formed by a coating method, a chemical plating method, a sputtering method, a vapor deposition method, a cathodic arc method, or a chemical vapor deposition method. Among them, the vapor deposition method includes an electron beam evaporation method, a thermal evaporation method, The high frequency vapor deposition method, the laser vapor deposition method, and the like are not limited thereto. Here, in a method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency disclosed in the present invention, the first metal layer 13 is at least one selected from the group consisting of titanium, chromium, molybdenum, or silicon dioxide (SiO ₂ ). And the thickness of the first metal layer 13 may be 1 nanometer to 1 micrometer; in addition, the second metal layer 14 is aluminum, and the thickness of the second metal layer 14 may be 10 nanometers to 100 micrometers. In another aspect of the present invention, the first metal layer 13 is mainly titanium.

Step S4: forming a second patterned structure 15 on the second metal layer 14 by a second etching process. The second patterned structure 15 is located on one or both of the first patterned structure 11 and the spacer region 12. (Refer to FIG. 2D); in one embodiment, the second etching process is an anodized aluminum oxide (AAO) process, but it is not limited thereto. In the case of using anodized aluminum, it includes providing a second photoresist layer on the surface of the second metal layer 14 above the first patterned structure 11, so that the anodized aluminum can be selectively removed. The second metal layer 14 above the spacer region 12, therefore, the second patterned structure 15 may be formed on the second metal layer 14 above the spacer region 12, but the second metal layer 14 above the first patterned structure 11 is It will not have the second patterned structure 15. In another embodiment, in the method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency of the present invention, in step S4, the method further includes providing a second photoresist layer and a second metal layer 14 disposed above the space region 12. On the surface, the anodized aluminum treatment can selectively remove a portion of the second metal layer 14 above the first patterned structure 11. Therefore, the second patterned structure 15 can be formed on the first patterned structure 11. Two metal layers 14, but the second metal layer 14 above the spacer region 12 does not have the second patterned structure 15.

Step S5: The third patterned structure 15 is extended downward to a portion of the surface of the first metal layer 13 and the substrate 10 by a third etching process (refer to FIG. 2E); the method of the third etching process described herein may be the same The foregoing first etching process is not repeated here.

Step S6: The first metal layer 13 and the second metal layer 14 are removed from the substrate 10 by an acid solution to form a substrate 10 having a first patterned structure 11 and a second patterned structure 15 (see FIG. 2F), and the acid solution referred to here can be used, for example, oxalic acid (H ₂ C ₂ O ₄ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), etc. The time can be prepared by various acid solutions, for example, it is prepared by using hydrofluoric acid: nitric acid: acetic acid at a ratio of 2: 3: 10, and pickled for about 2 minutes.

Step S7: A filling layer 16 is formed in the second patterned structure 15 at a predetermined growth rate, as shown in FIG. 2G and a partial enlargement thereof as shown in FIG. 2H. Here, the filling layer 16 may be formed by a physical vapor deposition method (Physical Vapor Deposition) at a predetermined growth rate, for example, a sputtering method or an evaporation method, and the filling layer 16 is filled in the second patterned structure 15. , And the predetermined growth rate is preferably between 0.01 and 3.0 nanometers per second.

The shape of the aforementioned second patterned structure 15 is a one-micron-level groove structure, and its aspect ratio is between 0.3: 1 and 20: 1. And the micro-scale groove structure includes a polygonal structure, including a trapezoidal structure, a tapered structure, an arc structure, a columnar structure, or an angular structure. In addition, it should be particularly noted that the material used for the filling layer 16 is not particularly limited, and a material with a refractive index between 1.7 and 2.5 can be selected. For example, sapphire (refractive index 1.7), aluminum nitride AlN , Silicon nitride SiN, silicon dioxide SiO ₂ , titanium nitride TiN or gallium nitride (refractive index is 2.5) are all acceptable.

Please refer to FIG. 2I. It should be particularly noted that in addition to the filling layer 16 being filled in the second patterned structure 15, the filling layer 16 will also exist on the first patterned structure 11 and the space region 12. In addition, please also refer to FIG. 2J. This is another embodiment of the second patterned structure 15. The structural shape of the second patterned structure 15 is a pyramid-shaped sub-micron groove structure. In this embodiment, The filling layer 16 is made of gallium nitride material, and fills the horn-shaped groove voids in the second patterned structure 15 at a predetermined growth rate between 0.01 and 3.0 nanometers per second. Based on this, the present invention is applied The proposed manufacturing method of a patterned photovoltaic substrate with improved luminous efficiency is further applied to products made of light-emitting diodes, which can penetrate the sub-micron-level groove structure of the angular cone shape, which can increase the amount of light incident and pass through the filling layer 16 Filling in the second patterned structure 15 can avoid the phenomenon of total reflection of light, greatly increase the amount of light, and further improve the luminous efficiency.

In another embodiment of the present invention, the filling layer 16 includes aluminum nitride. If the substrate 10 is made of sapphire, since the refractive index of the aluminum nitride and the sapphire are similar, the critical angle of light entering different media can reach approximately 42.5 degrees, according to which the total reflection of light entering different media can be eliminated. In addition, in another embodiment of the present invention, the filling layer 16 is formed in the second patterned structure 15 of the substrate 10 by sputtering or atomic layer deposition, but it is not limited thereto.

In addition, in the method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency of the present invention, after step S7, it further includes providing a buffer layer 40 and a photovoltaic element to be formed on the substrate 20, so that the substrate 20 can be The buffer layer 40 and the photovoltaic element are combined to form a light-emitting diode 30 or a solar cell, which will be further described in FIG. 3A later.

Please refer to FIG. 2K, another embodiment of the present invention is a patterned photovoltaic substrate 20 with improved luminous efficiency, including: a first patterned structure 21, in this embodiment, the first patterned structure 21 is A micron-level groove structure; and a space region 22; a second patterned structure 25, which is a one-time micron-level groove structure, formed on one or both of the first patterned structure 21 and the spaced region 22 And a filling layer 26 disposed in the sub-micron-level groove structure of the second patterned structure 25. This embodiment is substantially the same as the manufacturing process of a patterned photovoltaic substrate 10 with improved luminous efficiency, except that the uneven pattern of the first patterned structure 21 is different. In this embodiment, a first photoresist layer (not shown) is provided on a part of the surface of the substrate 20, so that the first etching process is to selectively remove a part of the substrate 20 to form a micron-shaped groove having a conical shape. The first patterned structure 21 of the structure and the space region 22 of the planar structure; then, according to the aforementioned manufacturing process, the first patterned structure 21 includes a plurality of second patterned structures 25 to form a first patterned structure The patterned photovoltaic substrate 20 having the structure 21 and the second patterned structure 25 with improved luminous efficiency is then provided with a filling layer 26 and the second patterned structure 25 is filled and filled.

In one embodiment, the first patterned structure 21 or the second patterned structure 26 is conical, arc-shaped, cylindrical, pyramidal, or prismatic, or it may be a polygonal structure, including a trapezoidal structure. , A tapered structure, an arc structure, a column structure or an angular structure, etc., are not limited.

It should be particularly noted that the aspect ratio of the sub-micron-level groove structure of the second patterned structure 26 is between 0.3: 1 and 20: 1. The filling layer 26 is made of a material with a refractive index between 1.7 and 2.5, such as sapphire (refractive index 1.7) or gallium nitride (refractive index 2.5).

Please refer to FIG. 3A, which is a light-emitting diode 30 having a patterned photovoltaic substrate with improved luminous efficiency, and the photovoltaic substrate is like the aforementioned patterned photovoltaic substrate 20 with improved luminous efficiency. The first patterned structure 21, the space region 22, the second patterned structure 25, and the filling layer 26 are disposed in the second patterned structure 25 or above the substrate 20, and will not be repeated here.

A buffer layer 40 is disposed on the substrate 20. In the embodiment shown in FIG. 2H, the buffer layer 40 is disposed on the first patterned structure 21 and the space region 22, and the filling layer 26 is filled on Between the second patterned structure 25 and the buffer layer 40. In the embodiment shown in FIG. 2I, the filling layer 26 is filled on the first patterned structure 21, the space region 22, and the second patterned structure 25 respectively, and the buffer layer 40 is combined with the filling layer 26.

A photovoltaic element is disposed on the buffer layer 40, and the photovoltaic element includes: a first semiconductor layer 51, a light emitting layer 52, and a second semiconductor layer 53, wherein the first semiconductor layer 51 is bonded to the buffer layer 40; The light emitting layer 52 is sandwiched between the first semiconductor layer 51 and the second semiconductor layer 53.

The first semiconductor layer 51 and the second semiconductor layer 53 are relatively electrically conductive. For example, the first semiconductor layer 51 and the second semiconductor layer 53 are divided into a P-type semiconductor layer and an N-type semiconductor layer, or the first semiconductor layer 51. And the second semiconductor layer 53 is divided into an N-type semiconductor layer and a P-type semiconductor layer. In addition, the foregoing light emitting diode 30 of the present invention further includes a first electrode 54 and a second electrode 55. The first electrode 54 and the second electrode 55 are respectively electrically bonded to the first semiconductor layer 51 and The second semiconductor layer 53 and the first electrode 54 and the first semiconductor layer 51 or the second electrode 55 and the second semiconductor layer 53 have the same electrical properties. For example, the first electrode 54 and the first semiconductor layer 51 are both positively charged. The second electrode 55 and the second semiconductor layer 53 are both negatively charged, or the first electrode 54 and the first semiconductor layer 51 are both negatively charged, and the second electrode 55 and the second semiconductor layer 53 are both positively charged. In addition, in the light-emitting diode 30 disclosed in the present invention, the photoelectric element may be a linear light-emitting diode, a side-light-emitting light-emitting diode, or a flip-chip light-emitting diode, and the present invention is not limited thereto. herein.

Please refer to FIG. 3B. It should be particularly noted that the substrate 20 used in the light-emitting diode 30 provided by the present invention has a filling layer 26 and is disposed at least in the second patterned structure 25. When the layer 40 is disposed above the substrate 20, a bonding portion 261 is provided between the buffer layer 40 and the filling layer 26. As shown in FIG. 2H, the bonding portion 261 is filled and filled in the second patterned structure 25. Inside, then the buffer layer 40 will be combined with the spacer region, the filling layer and the first patterned structure, and the joint portion 261 presents a flat structure; for another embodiment, as shown in FIG. 2I or FIG. 2J, the filling layer 26 In addition to being filled in the second patterned structure, it is evenly arranged on the gap region and the first patterned structure. Therefore, the joint portion 261 also presents a relatively flat structure; please refer to FIG. 3B. In another embodiment, When the filling layer 26 is filled in the second patterned structure 25 and bonded to the buffer layer 40, the joint portion 261 has a recessed structure, which is particularly suitable when the aspect ratio of the second patterned structure 25 belongs to a deeper structure. Sputtering process, first the second After filling the deep voids of the structure 25 (herein, the filling layer 26), the MOCVD epitaxy rate is subsequently controlled to control the horizontal and vertical growth, so that the buffer layer 40 continues on top of this filling layer 26, so that In the overall structure, avoid the occurrence of hollow structures.

In addition, in the foregoing light emitting diode of the present invention, the buffer layer 40 may be a gallium nitride (GaN), aluminum nitride (AlN), aluminum gallium nitride (AlGaN), or the like, or a combination thereof. To reduce the stress caused by the lattice mismatch between the substrate 20 (such as a sapphire substrate) and the photovoltaic element (such as a gallium nitride epitaxial layer of a light emitting diode), thereby reducing defects in the photovoltaic element In addition to using a gallium nitride epitaxial layer as the photovoltaic element to form a light emitting diode 30, in another aspect of the present invention, a solar substrate can be used as the photovoltaic element to A solar cell is formed. At this time, the buffer layer 40 can also be an amorphous silicon carbide, and can also be used to lower the lattice between the substrate 20 (such as a sapphire substrate) and the solar single crystal layer or solar polycrystalline layer. The stress caused by the mismatch further reduces the number of defects in the photovoltaic element, and the present invention is not limited to this.

According to this, the light-emitting diode 30 provided by the present invention, because the substrate 20 used by it is a patterned photovoltaic substrate with improved luminous efficiency as described above, which passes through the second patterned structure 25 to be one micron The level groove structure can increase the amount of incident light. Furthermore, the filling layer 26 is filled in the second patterned structure 25 by using a predetermined growth rate, which can avoid the phenomenon of total reflection of light. Increasing the amount of incident light further improves the light emitting efficiency, so that the entire light emitting diode 30 has more stable and excellent light emitting efficiency and performance.

Please refer to FIG. 4 and FIG. 5, which are the diffuse reflectance (DR; diffuse reflectance) and diffuse transmittance (DT) of various ranges of light wavelengths in the groove structure with different aspect ratios on the substrate. Experimental data graph. Figure 6 shows the relationship between diffuse reflectance, diffuse transmittance, and aspect ratio, and the AR value marked in the figure is the aspect ratio. It can be seen in FIGS. 4 and 5 that when there is no sub-micron-level groove structure or micro-level groove structure on the substrate, and only a sapphire substrate (Bare), the detector detects The ratio of DR to DT is maintained at 0.2%.

However, when a sub-micron-level groove structure or a micro-level groove structure is provided on the substrate, at the same light wavelength, as the aspect ratio increases, DR and DT increase accordingly, which can effectively improve LED light extraction. effectiveness. Figure 4 also shows that the larger the aspect ratio, the higher the DR and DT.

Please refer to FIG. 7 and FIG. 8, which are side views of an electron microscope for growing an LED structure layer on a groove structure substrate with different aspect ratios. As mentioned above, although the technical features of providing a sub-micron-level groove structure or a micro-level groove structure on a substrate have been disclosed in the prior art, and from the above, it can be known that as the depth-to-width ratio of the groove structure increases, the DR And DT increased accordingly. However, in an actual epitaxial process, if an epitaxial layer is formed on a substrate using the MOCVD technology, a technical bottleneck in which the groove structure with a high aspect ratio cannot be completely filled will be encountered. As shown in FIG. 8, although a groove structure with a lower aspect ratio (lighter) is easier to fill out, as shown in FIG. 7, a groove structure with a higher aspect ratio (deeper) will not be easy to fill. Filling, therefore, will make the LED epitaxial structure leave a gap in the nanoscale-patterned sapphire substrates (NPSS; nano-patterned sapphire substrates) with high aspect ratio, so that the light emitted by the LED cannot be smoothly derived from the sapphire substrate. In other words, even if a sub-micron level groove structure or a micron-level groove structure with a high aspect ratio is provided on the substrate, the light extraction efficiency of the LED cannot be effectively improved without breaking the existing epitaxial process.

Please refer to FIG. 9, FIG. 10, and FIG. 11, which are LED structure diagrams in which the groove structure on the substrate has a gap, the LED structure without the groove structure on the substrate, and the LED structure with the groove structure on the substrate completely filled. . Figure 9 shows the aforementioned groove structure with a high aspect ratio. Although a substrate with a higher aspect ratio can theoretically improve the light extraction efficiency, since this groove is a sub-micron groove structure or a micron-level groove The groove structure, so after the subsequent MOCVD process, the groove structure will be as shown in Figure 9. It can be seen in Figure 9 that the groove structure on the substrate has gaps, so when light is incident from the medium of the LED When it comes to the groove structure on the substrate, the groove structure on the substrate is an air medium, and its refractive index is 1, and the LED epitaxial layer on the substrate uses gallium nitride as an example, and its refractive index is 2.5. Considering the situation of total reflection, according to the optical snell's law, the light of the LED will generate a critical angle of 23.5 degrees, so that the light is reflected back to the epitaxial layer of the LED and cannot escape to the atmosphere.

As shown in FIG. 10, it is an embodiment of a non-groove structure on a substrate. Therefore, taking a sapphire substrate (Sapphire) as an example, its refractive index is 1.7, and gallium nitride has a refractive index of 2.5. Reflected condition, the LED light will produce a critical angle of 42.5 degrees. As shown in FIG. 11, it is another embodiment of the groove structure, but it is not limited thereto. The focus of the present invention is that the groove structure on the substrate is completely filled. In the case that the sub-micron-level groove structure or the micro-level groove structure can still be maintained on the upper surface, the LED light can still generate a critical angle of 42.5 degrees. Accordingly, the LED light extraction efficiency can be effectively improved. In other words, although NPSS with a high aspect ratio can improve the light extraction efficiency, the premise is that the groove structure of the LED must be filled and filled. According to this, a patterned photovoltaic substrate with improved luminous efficiency is proposed through the present invention. The second patterned structure is a micron-level groove structure, which can increase the amount of incident light. Furthermore, by using a predetermined The growth rate fills the filling layer within this second patterned structure, which can avoid the phenomenon of total reflection of light, greatly increase the amount of light incident, and further improve the luminous efficiency, thereby making the entire light emitting diode more stable and more stable. Excellent luminous efficiency and performance.

FIG. 12 is a comparison diagram of the luminous efficiency of LEDs filled with the groove structure on the various substrates of FIGS. 9 to 11, wherein the Y-axis refers to the light intensity, the unit is mcd (milli candela), and it is marked as HAR-LED. In the state of FIG. 9, the groove structure on the substrate has a voided LED structure. The B-LED designation refers to the LED structure without the groove structure on the substrate in the aspect of FIG. 10, and the LAR-LED is shown in FIG. 11. In aspects, the groove structure on the substrate completely fills the LED structure, and it can be known that the light intensity of the LAR-LED is the highest. In addition, the embodiment of FIGS. 9 to 11 is an experiment performed by using a planar sapphire substrate to excavate a nano hole and adding a microstructure pattern (nano pattern sapphire substrate NPSS). Also suitable for composite substrates.

The above embodiments are merely examples for the convenience of description. The scope of the claimed rights of the present invention should be based on the scope of the patent application, rather than being limited to the above embodiments.

S1, S2, S3, S4, S5, S6, S7‧‧‧ steps
10, 20‧‧‧ substrate
30‧‧‧light-emitting diode
11, 21‧‧‧ the first patterned structure
12, 22‧‧‧ Interval
13‧‧‧ first metal layer
14‧‧‧Second metal layer
15, 25‧‧‧ second patterned structure
16, 26‧‧‧ Filler
40‧‧‧ buffer layer
51‧‧‧First semiconductor layer
52‧‧‧Light-emitting layer
53‧‧‧Second semiconductor layer
54‧‧‧first electrode
55‧‧‧Second electrode
261‧‧‧Joint

FIG. 1 is a flowchart of steps in a method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency according to the present invention.
2A to 2J are schematic diagrams of an embodiment of a patterned photovoltaic substrate with improved luminous efficiency according to the present invention.
FIG. 2I is another embodiment of the filling layer.
FIG. 2J is another embodiment of the second patterned structure.
FIG. 2K is another embodiment of a patterned photovoltaic substrate with improved luminous efficiency proposed by the present invention.
FIG. 3A and FIG. 3B are light-emitting diodes of a patterned photovoltaic substrate with improved light-emitting efficiency according to the present invention.
FIG. 4 and FIG. 5 are experimental data diagrams of diffuse reflectance and diffuse transmittance in groove structures with different aspect ratios of light wavelengths on the substrate in various ranges.
FIG. 6 is a relationship diagram of diffuse reflectance, diffuse transmittance, and aspect ratio of a substrate with a groove structure when incident light is 450 mm.
FIG. 7 and FIG. 8 are electron microscope images of the grooved structure substrate with different aspect ratios after growing the LED structure layer.
FIG. 9 is a schematic diagram of an LED structure having a groove structure on a substrate and a light track travel diagram.
FIG. 10 is a schematic diagram of a structure of an LED without a groove structure on a substrate and a light track travel diagram.
FIG. 11 is a schematic diagram of an LED structure and a light track travel diagram of a groove structure completely filled on a substrate.
FIG. 12 is a comparison diagram of the luminous efficiency of the LEDs in the filled state of the groove structure on the various substrates of FIGS.

Claims (12)

A method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency, the steps include: step S1: providing a substrate; step S2: forming a first patterned structure and a space region on the surface of the substrate by a first etching process Step S3: forming a first metal layer and a second metal layer on the first patterned structure and the surface of the space region on the substrate; step S4: performing a second etching process on the second metal layer A second patterned structure is formed, and the second patterned structure is located on one or both of the first patterned structure and the space region; Step S5: the second pattern is made by a third etching process The structure extends downward to the first metal layer and a part of the surface of the substrate; step S6: removing the first metal layer and the second metal layer from the substrate by an acid treatment to form the substrate having the A first patterned structure and the substrate of the second patterned structure; and step S7: forming a filling layer to fill the second patterned structure at a predetermined growth rate, wherein the material used in the filling layer is Refractive index of between 1.7 to 2.5. According to the method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency as described in item 1 of the scope of the patent application, wherein the structure shape of the second patterned structure is a one-micron-level groove structure, and its aspect ratio is Between 0.3: 1 and 20: 1. The method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency as described in item 2 of the scope of the patent application, wherein the sub-micron level groove structure includes a polygonal structure. According to the method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency as described in item 1 of the scope of the patent application, the filling layer is filled in the second patterned structure by a physical vapor deposition method. The method for manufacturing a patterned photovoltaic substrate with improved luminous efficiency as described in item 1 or 4 of the scope of the patent application, wherein the predetermined growth rate is between 0.01 and 3.0 nanometers per second. A patterned photovoltaic substrate with improved luminous efficiency includes: a first patterned structure, which is a micron-scale protruding structure or a micron-scale groove structure; a space region; a second patterned structure, which is a micron Level groove structure formed on one or both of the first patterned structure and the space region; and a filling layer disposed in the sub-micron level groove structure of the second patterned structure, wherein The filling layer is made of a material with a refractive index between 1.7 and 2.5. The patterned photovoltaic substrate with improved luminous efficiency as described in item 6 of the scope of the patent application, wherein the first patterned structure or the second patterned structure is conical, arc-shaped, cylindrical, pyramidal, or Angle columnar. The patterned photovoltaic substrate with improved luminous efficiency as described in item 6 of the scope of the patent application, wherein the aspect ratio of the sub-micron groove structure is between 0.3: 1 and 20: 1. A light-emitting diode having a patterned photovoltaic substrate with improved luminous efficiency, comprising: a substrate, the substrate being a patterned photovoltaic substrate with improved luminous efficiency according to any one of claims 6-8 of the scope of patent application; A buffer layer is disposed on the substrate; and a photovoltaic element is disposed on the buffer layer, and the photovoltaic element includes: a first semiconductor layer, a light emitting layer, and a second semiconductor layer, wherein the first semiconductor The layer is bonded to the buffer layer; the light emitting layer is sandwiched between the first semiconductor layer and the second semiconductor layer. The light-emitting diode according to item 9 of the scope of patent application, further comprising a first electrode and a second electrode, the first electrode and the second electrode are respectively electrically connected to the first semiconductor layer and The second semiconductor layer. The light-emitting diode according to item 9 of the scope of the patent application, wherein a bonding portion is provided between the filling layer and the buffer layer. For example, the light emitting diode according to item 11 of the patent scope, wherein the joint portion has a recessed structure.