TWI860765B - Light emitting diode structure - Google Patents

Abstract

The present invention provides a light emitting diode structure, including a substrate, a semiconductor light emitting structure, and an electrode structure. The semiconductor light-emitting structure is located on the substrate and includes a light emitting surface. The electrode structure is located on the light emitting surface and includes a main electrode part, at least one primary electrode part and at least one transparent conductive part. A distance is maintained between the main electrode portion and each primary electrode portion, and each primary electrode portion is electrically connected to the main electrode portion through any transparent conductive portion as a current conduction path.

Description

LED structure

The present invention relates to a light-emitting diode structure, and in particular to a light-emitting diode structure that can improve light-emitting uniformity and light-emitting efficiency.

In recent years, LEDs have been widely used in lighting, medical and 3C products. LED chips are mainly made of different semiconductor materials. When the current flows through the connection surface of two semiconductor materials, the electroluminescent effect is generated to convert electrical energy into light energy, so that the LED chip can not only emit high-brightness light, but also save energy and electricity.

In terms of structural design, a metal electrode is set on the surface of the LED chip to be electrically connected to external components through welding wires. In order to improve the luminous uniformity of the LED chip, an extended electrode electrically connected to the metal electrode is additionally set on the chip surface. The extended electrode transmits the current to the area with lower luminous efficiency, so that more current passes through the connection surface of the semiconductor material to enhance the luminous effect. However, since the extended electrode has a certain width, a part of the luminous surface of the semiconductor material will be shielded by the opaque metal electrode and the extended electrode, thereby reducing the light-emitting area of the luminous surface, which will lead to a decrease in the luminous efficiency or brightness of the LED chip.

Therefore, how to design a light-emitting diode structure that can improve the above-mentioned problems is indeed a topic worth studying.

The purpose of this invention is to provide a light-emitting diode structure that can improve light-emitting uniformity and light-emitting efficiency.

To achieve the above-mentioned purpose, the light-emitting diode structure of the present invention includes a substrate, a semiconductor light-emitting structure and an electrode structure. The semiconductor light-emitting structure is located on the substrate, and the semiconductor light-emitting structure includes a light-emitting surface. The electrode structure is located on the light-emitting surface. The electrode structure includes a main electrode part, at least one transparent conductive part and at least one primary electrode part. The main electrode part and each secondary electrode part are spaced apart, and each secondary electrode part is electrically connected to the main electrode part through any transparent conductive part to serve as a current conduction path.

In one embodiment of the present invention, each transparent conductive part and the semiconductor light-emitting structure present high contact impedance or electrical non-conduction.

In one embodiment of the present invention, each transparent conductive part and the semiconductor light-emitting structure exhibit low contact impedance.

In one embodiment of the present invention, each transparent conductive part is composed of zinc oxide, indium tin oxide, indium zinc oxide or indium gallium zinc oxide.

In one embodiment of the present invention, the main electrode portion, at least one transparent conductive portion and at least one secondary electrode portion are respectively in direct contact with the semiconductor light-emitting structure, and a portion of each transparent conductive portion is sandwiched between the main electrode portion and the light-emitting surface.

In one embodiment of the present invention, the main electrode portion, the at least one transparent conductive portion and the at least one secondary electrode portion are respectively in direct contact with the semiconductor light-emitting structure, and a portion of each transparent conductive portion covers a partial outer surface of the main electrode portion.

In one embodiment of the present invention, at least one transparent conductive portion and at least one primary electrode portion are directly in contact with the semiconductor light-emitting structure, respectively, and the main electrode portion is formed on at least one transparent conductive portion and is indirectly in contact with the semiconductor light-emitting structure.

In one embodiment of the present invention, when at least one transparent conductive part is plural, one end of each transparent conductive part electrically connected to the main electrode part can be connected to each other.

In one embodiment of the present invention, the width of the transparent conductive portion is not less than 3μm.

In one embodiment of the present invention, at least one transparent conductive portion covers the remaining portion of the light-emitting surface except for the main electrode portion and at least one primary electrode portion.

In one embodiment of the present invention, the thickness of the transparent conductive portion is not less than 1000Å.

Accordingly, the light-emitting diode structure of the present invention can set at least one primary electrode portion at any position on the light-emitting surface where the current distribution needs to be controlled, and with the setting of at least one transparent conductive portion, the main electrode portion and each secondary electrode portion are electrically connected to transmit current. Accordingly, the current distribution of the light-emitting diode structure of the present invention on the light-emitting surface is more uniform, and at least one transparent conductive portion will not block light, thereby improving the light-emitting efficiency.

1, 1a, 1b, 1c, 1d: LED structure

10: Substrate

11: Metal point

20: Semiconductor light-emitting structure

21: First semiconductor layer

22: Second semiconductor layer

23: Luminous layer

24: Shiny surface

30, 30a, 30b, 30c, 30d: Electrode structure

31, 31a, 31b, 31c, 31d: Main electrode part

32, 32a, 32b, 32c, 32d: secondary electrode part

33, 33a, 33b, 33c, 33d: Transparent conductive part

Figure 1 is a top view of the first embodiment of the light-emitting diode structure of the present invention.

Figure 2 is a cross-sectional view of the first embodiment of the light-emitting diode structure of the present invention.

FIG3 is a top view of the second embodiment of the light-emitting diode structure of the present invention.

Figure 4 is a cross-sectional view of the second embodiment of the light-emitting diode structure of the present invention.

FIG5 is a top view of the third embodiment of the light-emitting diode structure of the present invention.

FIG6 is a cross-sectional view of the third embodiment of the light-emitting diode structure of the present invention.

FIG7 is a cross-sectional view of the fourth embodiment of the light-emitting diode structure of the present invention.

FIG8 is a top view of the fifth embodiment of the light-emitting diode structure of the present invention.

Since the various aspects and embodiments are only illustrative and non-restrictive, after reading this specification, a person with ordinary knowledge may also have other aspects and embodiments without departing from the scope of the invention. The features and advantages of these embodiments will be more prominent according to the following detailed description and patent application scope.

In this article, "a" or "an" is used to describe the elements and components described herein. This is only for the convenience of explanation and to provide a general meaning for the scope of the present invention. Therefore, unless it is obvious that it is otherwise intended, such description should be understood to include one or at least one, and the singular also includes the plural.

In this document, the terms "including", "having" or any other similar terms are intended to cover a non-exclusive inclusion. For example, an element or structure containing multiple elements is not limited to those elements listed herein, but may include other elements that are not expressly listed but are generally inherent to the element or structure.

Please refer to Figures 1 and 2 for the related drawings of the first embodiment of the light-emitting diode structure of the present invention, wherein Figure 2 is a cross-sectional view along the line segment AA ' of Figure 1. As shown in Figures 1 and 2, the light-emitting diode structure 1 of the present invention includes a substrate 10, a semiconductor light-emitting structure 20 and an electrode structure 30. The substrate 10 is a basic structural component of the light-emitting diode structure 1, and the substrate 10 can be a silicon (Si) substrate, an aluminum nitride (AlN) substrate, a copper tungsten (CuW) substrate or a molybdenum (Mo) substrate, but the present invention is not limited thereto. The substrate 10 includes a plurality of metal dots 11, and the plurality of metal dots 11 are arranged on a surface of one side of the substrate 10 (for example, a surface of the substrate 10 facing the semiconductor light-emitting structure 20).

The semiconductor light-emitting structure 20 is located on the substrate 10, and the semiconductor light-emitting structure 20 is used to generate an electroluminescent effect to emit light. The semiconductor light-emitting structure 20 includes a light-emitting surface 24, and the light-emitting surface 24 is the other side opposite to the side of the substrate 10. In one embodiment of the present invention, the semiconductor light-emitting structure 20 may further include a first semiconductor layer 21 and a second semiconductor layer 22. The first semiconductor layer 21 is adjacent to the substrate 10. In the following embodiments, the first semiconductor layer 21 is illustrated by using gallium phosphide (GaP) as an example, but the present invention is not limited thereto. The first semiconductor layer 21 may also be made of gallium arsenide (GaAs), gallium nitride (GaN) or other semiconductor materials. The first semiconductor layer 21 can be formed into an N-type semiconductor or a P-type semiconductor by doping different metals.

The second semiconductor layer 22 is located on the first semiconductor layer 21. In the following embodiments, the second semiconductor layer 22 is illustrated by using indium gallium aluminum phosphide (AlGaInP), but the present invention is not limited thereto. The second semiconductor layer 22 can also be made of gallium aluminum arsenide (AlGaAs) or other semiconductor materials. The second semiconductor layer 22 can also be formed into an N-type semiconductor or a P-type semiconductor by doping different metals. When the first semiconductor layer 21 is an N-type semiconductor, the second semiconductor layer 22 is a P-type semiconductor; conversely, when the first semiconductor layer 21 is a P-type semiconductor, the second semiconductor layer 22 is an N-type semiconductor. A light-emitting layer 23 is formed between the first semiconductor layer 21 and the second semiconductor layer 22 (i.e., the interface between the first semiconductor layer 21 and the second semiconductor layer 22). Here, the light-emitting layer 23 is a multiple quantum well (MQW) layer.

The electrode structure 30 is located on the light-emitting surface 24 of the semiconductor light-emitting structure 20, and the electrode structure 30 can be connected to a power source. By supplying power to the electrode structure 30, a current is generated from the electrode structure 30 to the plurality of metal points 11 of the substrate 10, so that the current flows through the light-emitting layer 23 to emit light. In the present invention, the electrode structure 30 at least includes a main electrode portion 31, at least one primary electrode portion 32, and at least one transparent conductive portion 33. The main electrode portion 31 and at least one primary electrode portion 32 are made of metal or alloy, and a distance is maintained between the main electrode portion 31 and each secondary electrode portion 32. The main electrode portion 31 is used as a pad for welding a metal line electrically connected to the power source or/and other electronic components. At least one primary electrode portion 32 is used as an additional metal point for transmitting current. The number and location of at least one primary electrode portion 32 can be changed according to different design requirements. For example, in each embodiment of the present invention, at least one primary electrode portion 32 includes four secondary electrode portions 32, and each secondary electrode portion 32 is disposed in a region with lower luminous efficiency on the luminous surface 24 (for example, uniformly and dispersedly disposed around the main electrode portion 31), but the present invention is not limited thereto.

Each transparent conductive portion 33 is connected to the main electrode portion 31 and any one of the secondary electrode portions 32, so that each secondary electrode portion 32 is electrically connected to the main electrode portion 31 through any one of the transparent conductive portions 33 as a current transmission path; that is, the current can be transmitted from the main electrode portion 31 to the corresponding secondary electrode portion 32 through the transparent conductive portion 33, so that the secondary electrode portion 32 becomes another current transmission source. In one embodiment of the present invention, each transparent conductive portion 33 is a transparent conductive film composed of zinc oxide (ZnO), indium tin oxide (ITO), indium zinc oxide (IZO) or indium gallium zinc oxide (IGZO). In terms of structural design, the thickness of the transparent conductive portion 33 is not less than 1000Å. If the transparent conductive portion 33 is roughly in a straight line shape, the width of the transparent conductive portion 33 (i.e. the radial distance perpendicular to the direction of the current flowing mainly through the transparent conductive portion 33) is not less than 3μm, so as to provide a current transmission effect.

In the present invention, each transparent conductive portion 33 is in direct contact with the semiconductor light emitting structure 20, and according to different design requirements, each transparent conductive portion 33 can present different contact impedances or electrical conduction effects with the semiconductor light emitting structure 20. For example, in one embodiment of the present invention, by selecting and designing the materials of each transparent conductive portion 33, each transparent conductive portion 33 can present high contact impedance (such as Schottky contact or ohmic contact with high contact impedance) or electrical non-conduction with the semiconductor light emitting structure 20. Accordingly, due to the characteristic that the current will choose to transmit along a path with lower impedance, the current will hardly be transmitted directly downward from the transparent conductive portion 33 to the semiconductor light-emitting structure 20, but will be concentrated and gathered laterally to the corresponding sub-electrode portion 32, thereby achieving the goal of guiding the current to the area with lower light-emitting efficiency.

In the first embodiment of the light-emitting diode structure 1 of the present invention, after the semiconductor light-emitting structure 20 is formed on the substrate 10 by an epitaxial process, at least one primary electrode portion 32, at least one transparent conductive portion 33 and a main electrode portion 31 are sequentially formed on the light-emitting surface 24 of the semiconductor light-emitting structure 20 to form the entire electrode structure 30. In terms of structural design, the main electrode portion 31, at least one primary electrode portion 32 and at least one transparent conductive portion 33 of the electrode structure 30 are directly in contact with the semiconductor light-emitting structure 20, respectively, and a portion of each transparent conductive portion 33 is sandwiched between the main electrode portion 31 and the light-emitting surface 24 of the semiconductor light-emitting structure 20. In addition, when at least one transparent conductive portion 33 is plural, one end of each transparent conductive portion 33 electrically connected to the main electrode portion 31 can be connected to each other, for example, forming a ring structure as shown in FIG. 1 . Accordingly, the main electrode portion 31 and the sub-electrode portion 32 can be electrically connected via the transparent conductive portion 33.

When the main electrode portion 31 is powered, the current can be directly transmitted from the main electrode portion 31 through the semiconductor light-emitting structure 20 toward the metal point 11 of the substrate 10. In addition, the current can also be concentrated from the main electrode portion 31 and laterally gathered to each sub-electrode portion 32, and then directly transmitted from each sub-electrode portion 32 through the semiconductor light-emitting structure 20 toward the metal point 11 of the substrate 10. Accordingly, the light-emitting diode structure 1 of the present invention can achieve a uniform current distribution effect through the electrode structure 30, and the light emitted by the light-emitting layer 23 of the semiconductor light-emitting structure 20 can be directly emitted from the light-emitting surface 24 or emitted after passing through each transparent conductive portion 33, thereby reducing the area range where the light may be shielded. In addition, by coordinating the positions of the electrode structure 30 and the multiple metal dots 11 of the substrate 10, the light-emitting diode structure 1 of the present invention can provide better light-emitting efficiency and light-emitting uniformity.

Please refer to FIG. 3 and FIG. 4 for the relevant drawings of the second embodiment of the light emitting diode structure of the present invention, wherein FIG. 4 is a cross-sectional view along the line segment AA ' of FIG. 3. As shown in FIG. 3 and FIG. 4, in this embodiment, after the semiconductor light emitting structure 20 is formed on the substrate 10 by an epitaxial process, at least one primary electrode portion 32a, a main electrode portion 31a and at least one transparent conductive portion 33a are sequentially formed on the light emitting surface 24 of the semiconductor light emitting structure 20 to form an overall electrode structure 30a. In terms of structural design, the main electrode portion 31a, at least one secondary electrode portion 32a and at least one transparent conductive portion 33a of the electrode structure 30a are respectively in direct contact with the semiconductor light-emitting structure 20, and a portion of each transparent conductive portion 33a covers a partial outer surface of the main electrode portion 31a. In addition, when there are plural at least one transparent conductive portion 33a, one end of each transparent conductive portion 33a electrically connected to the main electrode portion 31a can be connected to each other, for example, forming a ring structure as shown in Figures 3 and 4. Accordingly, the main electrode portion 31a and the secondary electrode portion 32a can be electrically connected through the transparent conductive portion 33a. Since the operating principle of the second embodiment of the LED structure 1a of the present invention is the same as that of the first embodiment and can achieve similar effects, it will not be repeated here.

Please refer to FIG. 5 and FIG. 6 for the relevant drawings of the third embodiment of the light emitting diode structure of the present invention, wherein FIG. 6 is a cross-sectional view along the line segment AA ' of FIG. 5. As shown in FIG. 5 and FIG. 6, in this embodiment, after the semiconductor light emitting structure 20 is formed on the substrate 10 by an epitaxial process, at least one primary electrode portion 32b, at least one transparent conductive portion 33b and a main electrode portion 31b are sequentially formed on the light emitting surface 24 of the semiconductor light emitting structure 20 to form an overall electrode structure 30b. In terms of structural design, at least one primary electrode portion 32b and at least one transparent conductive portion 33b of the electrode structure 30b are in direct contact with the semiconductor light-emitting structure 20, respectively, and the main electrode portion 31b is formed on at least one transparent conductive portion 33b and is in indirect contact with the semiconductor light-emitting structure 20. In addition, when there are plural at least one transparent conductive portion 33b, one end of each transparent conductive portion 33b electrically connected to the main electrode portion 31b can be connected to each other, for example, forming a circular structure as shown in Figures 5 and 6. Accordingly, the main electrode portion 31b and the secondary electrode portion 32b are electrically connected via the transparent conductive portion 33b.

When the main electrode portion 31b is powered, the current can almost only be concentrated and laterally gathered from the main electrode portion 31b to each sub-electrode portion 32b, and then directly transmitted from each sub-electrode portion 32b through the semiconductor light-emitting structure 20 toward the metal point 11 of the substrate 10. In addition to the above-mentioned design, since the operating principle of the third embodiment of the light-emitting diode structure 1b of the present invention is roughly the same as the above-mentioned first and second embodiments, and can achieve similar effects, it will not be repeated here.

Please refer to FIG. 7 for a cross-sectional view of the fourth embodiment of the light-emitting diode structure of the present invention. This embodiment is a variation of the aforementioned first embodiment. As shown in FIG. 7 , in this embodiment, the light-emitting diode structure 1c of the present invention can present a low contact impedance (e.g., an ohmic contact with low contact impedance) between each transparent conductive portion 33c and the semiconductor light-emitting structure 20 by selecting and designing the material of the transparent conductive portion 33c. Accordingly, although part of the current will choose to be transmitted directly from the transparent conductive portion 33c through the semiconductor light-emitting structure 20 toward the metal point 11 of the substrate 10, most of the current will still be gathered laterally to the corresponding sub-electrode portion 32c, thereby achieving the goal of guiding the current to the area with lower light-emitting efficiency.

Please refer to FIG8 for a top view of the fifth embodiment of the light-emitting diode structure of the present invention. This embodiment is a variation of the second embodiment described above. As shown in FIG8 , in this embodiment, the light-emitting diode structure 1d of the present invention covers the remaining portion of the light-emitting surface 24 of the semiconductor light-emitting structure 20 except for the main electrode portion 31d and at least one primary electrode portion 32d by a large-area transparent conductive portion 33d, and a portion of the transparent conductive portion 33d covers a partial outer surface of the main electrode portion 31d. That is to say, in this embodiment, by expanding the coverage area of the transparent conductive part 33d, the entire electrode structure 30d (including the main electrode part 31d, four sub-electrode parts 32d and one large-area transparent conductive part 33d) will completely cover the light-emitting surface 24 of the semiconductor light-emitting structure 20. Accordingly, the main electrode part 31d and the sub-electrode part 32d can be electrically connected through the transparent conductive part 33d. In addition to the above-mentioned design, since the operating principle of the fifth embodiment of the light-emitting diode structure 1d of the present invention is roughly the same as that of the above-mentioned second embodiment, and can achieve similar effects, it will not be repeated here.

The above embodiments are essentially only for auxiliary explanation and are not intended to limit the embodiments of the subject matter of the application or the application or use of such embodiments. In addition, although at least one exemplary embodiment has been proposed in the above embodiments, it should be understood that there are still a large number of variations of the present invention. It should also be understood that the embodiments described herein are not intended to limit the scope, use or configuration of the claimed subject matter in any way. On the contrary, the above embodiments will provide a simple guide for those with ordinary knowledge in the field to implement one or more of the embodiments described. Furthermore, various changes can be made to the functions and arrangements of the components without departing from the scope defined by the scope of the patent application, and the scope of the patent application includes known equivalents and all foreseeable equivalents at the time of filing the present patent application.

1: LED structure

10: Substrate

11: Metal point

20: Semiconductor light-emitting structure

21: First semiconductor layer

22: Second semiconductor layer

23: Luminous layer

24: Shiny surface

30: Electrode structure

31: Main electrode part

32: Sub-electrode part

33: Transparent conductive part

Claims (10)

A light-emitting diode structure includes: a substrate; a semiconductor light-emitting structure located on the substrate, the semiconductor light-emitting structure includes a light-emitting surface; and an electrode structure located on the light-emitting surface, the electrode structure includes a main electrode portion, at least one secondary electrode portion and at least one transparent conductive portion, a distance is maintained between the main electrode portion and each of the secondary electrode portions, and each of the secondary electrode portions is electrically connected to the main electrode portion through any of the transparent conductive portions to serve as a current conduction path; wherein when the at least one transparent conductive portion is plural, one end of each of the transparent conductive portions electrically connected to the main electrode portion can be connected to each other. The light-emitting diode structure as described in claim 1, wherein each transparent conductive part and the semiconductor light-emitting structure exhibit high contact impedance or electrical non-conduction. The light-emitting diode structure as described in claim 1, wherein each transparent conductive portion and the semiconductor light-emitting structure exhibit low contact impedance. The light-emitting diode structure as described in claim 1, wherein each of the transparent conductive parts is composed of zinc oxide, indium tin oxide, indium zinc oxide or indium gallium zinc oxide. The light-emitting diode structure as described in claim 1, wherein the main electrode portion, the at least one transparent conductive portion and the at least one primary electrode portion are respectively in direct contact with the semiconductor light-emitting structure, and a portion of each transparent conductive portion is sandwiched between the main electrode portion and the light-emitting surface. The light-emitting diode structure as described in claim 1, wherein the main electrode portion, the at least one transparent conductive portion and the at least one secondary electrode portion are respectively in direct contact with the semiconductor light-emitting structure, and a portion of each transparent conductive portion covers a partial outer surface of the main electrode portion. The light-emitting diode structure as described in claim 1, wherein the at least one transparent conductive portion and the at least one primary electrode portion are respectively in direct contact with the semiconductor light-emitting structure, and the main electrode portion is formed on the at least one transparent conductive portion and is in indirect contact with the semiconductor light-emitting structure. The light-emitting diode structure as described in claim 1, wherein the width of the transparent conductive portion is not less than 3μm. The light-emitting diode structure as described in claim 1, wherein the at least one transparent conductive portion covers the remaining portion of the light-emitting surface except for the main electrode portion and the at least one primary electrode portion. The light-emitting diode structure as described in claim 1, wherein the thickness of the transparent conductive portion is not less than 1000Å.