CN104779328A - LED structure - Google Patents

Abstract

The invention provides a light emitting diode structure. The light emitting diode structure comprises a substrate, an N-type semiconductor layer, a light emitting layer and a P-type semiconductor layer. The N-type semiconductor layer is arranged on the substrate. The light-emitting layer is suitable for emitting light with a main light-emitting wavelength of 365 nm to 490 nm and is arranged on the N-type semiconductor layer. The P-type semiconductor layer is disposed on the light emitting layer and includes a P-type AlGaN layer. The thickness of the P-type aluminum gallium nitride layer accounts for more than 85% of the thickness of the whole P-type semiconductor layer.

Description

LED structure

technical field

The present invention relates to a semiconductor structure, and more particularly to a light emitting diode structure.

Background technique

With the advancement of semiconductor technology, today's light-emitting diodes have a high-brightness output. In addition, light-emitting diodes have the advantages of power saving, small size, low-voltage drive, and mercury-free. Therefore, light-emitting diodes have been widely used in displays and lighting and other fields. Generally speaking, light-emitting diodes are manufactured using wide-bandgap semiconductor materials, such as gallium nitride (GaN) and other materials. However, when the light-emitting layer of the light-emitting diode emits near-UV light or blue light, the P-type semiconductor layer formed by gallium nitride will absorb light with a wavelength of about 365-490 nm, that is, it will absorb near-UV light and blue light. This further affects the light extraction efficiency of the overall light emitting diode.

Contents of the invention

The invention provides a light emitting diode structure with better light extraction efficiency.

The LED structure of the present invention includes a substrate, an N-type semiconductor layer, a light-emitting layer and a P-type semiconductor layer. The N-type semiconductor layer is configured on the substrate. The light-emitting layer is suitable for emitting light with a main light-emitting wavelength between 365 nm and 490 nm and is disposed on the N-type semiconductor layer. The P-type semiconductor layer is disposed on the light-emitting layer and includes a P-type AlGaN layer. The thickness of the P-type AlGaN layer accounts for more than 85% of the thickness of the entire P-type semiconductor layer.

In an embodiment of the present invention, the above-mentioned P-type semiconductor layer is a P-type AlGaN layer.

In an embodiment of the present invention, the above-mentioned P-type semiconductor layer further includes a P-type GaN layer disposed on the P-type AlGaN layer. The thickness of the P-type gallium nitride layer accounts for less than 15% of the thickness of the entire P-type semiconductor layer.

In an embodiment of the present invention, the above-mentioned P-type AlGaN layer includes a first P-type AlGaN layer and a second P-type AlGaN layer. The aluminum content in the first P-type AlGaN layer is different from the aluminum content in the second P-type AlGaN layer.

In an embodiment of the present invention, the above-mentioned first P-type AlGaN layer is located between the second P-type AlGaN layer and the light-emitting layer, and the aluminum content in the first P-type AlGaN layer greater than the aluminum content in the second P-type AlGaN layer.

In an embodiment of the present invention, the material of the above-mentioned first P-type AlGaN layer is AlxGa1-xN, and x is 0.09˜0.2.

In an embodiment of the present invention, the material of the second P-type AlGaN layer is AlyGa1-yN, and y is 0.01˜0.15.

In an embodiment of the present invention, the thickness of the second P-type AlGaN layer is greater than the thickness of the first P-type AlGaN layer.

In an embodiment of the present invention, the P-type doping concentration in the first P-type AlGaN layer is greater than the P-type doping concentration in the second P-type AlGaN layer.

In an embodiment of the present invention, the above-mentioned P-type semiconductor layer further includes a P-type AlInGaN layer disposed between the P-type AlGaN layer and the light-emitting layer.

In an embodiment of the present invention, the above-mentioned N-type semiconductor layer is an N-type GaN layer.

In an embodiment of the present invention, the above light emitting diode structure further includes an N-type electrode and a P-type electrode. The N-type electrode is arranged on the N-type semiconductor layer not covered by the light-emitting layer, and is electrically connected with the N-type semiconductor layer. The P-type electrode is disposed on the P-type semiconductor layer and electrically connected with the P-type semiconductor layer.

In an embodiment of the present invention, the above light emitting diode structure further includes a transparent conductive layer disposed on the P-type semiconductor layer.

Based on the above, since the thickness of the P-type AlGaN layer of the present invention accounts for more than 85% of the thickness of the entire P-type semiconductor layer, it can reduce the absorption of near-UV light or blue light emitted by the light-emitting layer by the P-type semiconductor layer. In this way, the light emitting diode structure of the present invention can have better light extraction efficiency.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.

Description of drawings

FIG. 1 shows a schematic cross-sectional view of a light emitting diode structure according to an embodiment of the present invention;

2 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention;

3 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention;

4 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention;

5 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention;

FIG. 6 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention.

Explanation of reference signs:

100a, 100b, 100c, 100d, 100e, 100f: light emitting diode structure;

110: substrate;

120: N-type semiconductor layer;

130: luminescent layer;

140a, 140b, 140c, 140d, 140e: P-type semiconductor layer;

142a, 142b, 142d: P-type aluminum gallium nitride layer;

142c1, 142e1: the first P-type aluminum gallium nitride layer;

142c2, 142e2: the second P-type aluminum gallium nitride layer;

144b: P-type gallium nitride layer;

144d, 144e: P-type aluminum indium gallium nitride layer;

150: N-type electrode;

160: P-type electrode;

170: transparent conductive layer;

T1, T2: Thickness.

Detailed ways

FIG. 1 is a schematic cross-sectional view of a light emitting diode structure according to an embodiment of the present invention. Please refer to FIG. 1 , in the present embodiment, the LED structure 100 a includes a substrate 110 , an N-type semiconductor layer 120 , a light-emitting layer 130 and a P-type semiconductor layer 140 a. The N-type semiconductor layer 120 is disposed on the substrate 110 . The light-emitting layer 130 is suitable for emitting light with a main light-emitting wavelength between 365 nm and 490 nm and is disposed on the N-type semiconductor layer 120 . The P-type semiconductor layer 140a is disposed on the light emitting layer 130 and includes a P-type AlGaN layer 142a. The thickness of the P-type AlGaN layer 142a accounts for more than 85% of the thickness of the entire P-type semiconductor layer 140a.

In detail, in this embodiment, the substrate 110 is, for example, a sapphire substrate, and the light emitting layer 130 is, for example, a gallium nitride/indium gallium nitride quantum well structure, but not limited thereto. The N-type semiconductor layer 120 is located between the substrate 110 and the light-emitting layer 130 , and a part of the N-type semiconductor layer 120 is exposed outside the light-emitting layer 130 . Here, the N-type semiconductor layer 120 is specifically an N-type gallium nitride layer. As shown in FIG. 1 , the P-type semiconductor layer 140a of this embodiment is specifically a P-type AlGaN layer 142a, which means that the entire P-type semiconductor layer 140a is formed of a single material, ie, AlGaN. Preferably, the thickness of the P-type AlGaN layer 142a is 30 nm to 100 nm. In addition, the light emitting diode structure 100a of this embodiment also includes an N-type electrode 150 and a P-type electrode 160, wherein the N-type electrode 150 is disposed on the N-type semiconductor layer 120 not covered by the light-emitting layer 130 and is connected to the N-type semiconductor layer 120 are electrically connected, and the P-type electrode 160 is disposed on the P-type semiconductor layer 140a and electrically connected to the P-type semiconductor layer 140a. It can be seen from the arrangement of the above components that the light emitting diode structure 100 a of this embodiment is specifically a blue light emitting diode structure.

Since the P-type semiconductor layer 140a in this embodiment is specifically the P-type AlGaN layer 142a, and the material properties of the P-type AlGaN layer 142a do not absorb light in the near-UV light or blue light band. Therefore, when the light-emitting layer 130 emits light, the light can directly pass through the P-type semiconductor layer 140a without being absorbed. In this way, the light emitting diode structure 100a of this embodiment can have better light extraction efficiency.

It must be noted here that the following embodiments use the component numbers and part of the content of the previous embodiments, wherein the same numbers are used to denote the same or similar components, and descriptions of the same technical content are omitted. For the description of omitted parts, reference may be made to the foregoing embodiments, and the following embodiments will not be repeated.

FIG. 2 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention. Please refer to FIG. 2, the light emitting diode structure 100b of this embodiment is similar to the light emitting diode structure 100a of FIG. 142b and a P-type GaN layer 144b, wherein the P-type GaN layer 144b is disposed on the P-type AlGaN layer 142b. In particular, in this embodiment, the thickness of the P-type GaN layer 142b accounts for more than 85% of the thickness of the overall P-type semiconductor layer 140b, in other words, the thickness of the P-type GaN layer 144b accounts for 15% or less of the thickness of 140b. Preferably, the thickness of the P-type GaN layer 144b is less than 10 nm.

In this embodiment, the thickness of the P-type AlGaN layer 142b accounts for more than 85% of the thickness of the entire P-type semiconductor layer 140b, and the material properties of the P-type AlGaN layer 142b do not absorb blue light. According to the Beer-Lambert law, when a beam of parallel monochromatic light passes through a uniform non-scattering light-absorbing substance vertically, its absorbance is proportional to the concentration of the light-absorbing substance and the thickness of the absorbing layer. Therefore, when the light-emitting layer 130 emits light, since the thickness of the P-type gallium nitride layer 144b that absorbs blue light waves is much smaller than the thickness of the P-type aluminum gallium nitride layer 142b, the absorption of the light-emitting layer by the P-type semiconductor layer 140b can be reduced. 130 emits near UV light or blue light. In this way, the light emitting diode structure 100b of this embodiment can have better light extraction efficiency.

FIG. 3 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention. Please refer to FIG. 3, the light emitting diode structure 100c of this embodiment is similar to the light emitting diode structure 100a of FIG. , wherein the P-type AlGaN layer includes a first P-type AlGaN layer 142c1 and a second P-type AlGaN layer 142c2, and the aluminum content in the first P-type AlGaN layer 142c1 is different from that of the first P-type AlGaN layer 142c1 Al content in the P-type AlGaN layer 142c2. Preferably, the first P-type AlGaN layer 142c1 is located between the second P-type AlGaN layer 142c2 and the light-emitting layer 130, and the aluminum content in the first P-type AlGaN layer 142c1 is greater than that of the second P-type AlGaN layer 142c1. Aluminum content in the P-type AlGaN layer 142c2. Here, the material of the first P-type AlGaN layer 142c1 is _{AlxGa1 -xN} , where x is 0.09˜0.2. The material of the second P-type AlGaN layer 142c2 is _{AlyGa1 -yN} , where y is 0.01˜0.15. The thickness T2 of the second P-type AlGaN layer 142c2 is greater than the thickness T1 of the first P-type AlGaN layer 142c1.

It should be noted that the P-type AlGaN layer can reduce light absorption, but if the aluminum content in the P-type AlGaN layer is too high, more epitaxial defects will cause the loss of recombined carriers and increase the light emission. Heat inside the diode structure. Furthermore, the increase of the aluminum content in the p-type AlGaN layer will cause another effect, which is to increase the resistance of the p-type AlGaN layer and make electrode fabrication more difficult. Therefore, the light-emitting diode structure 100c of this embodiment passes through the first P-type aluminum gallium nitride layer 142c1 close to the light-emitting layer 130, which has a high aluminum content, a relatively large bandgap, and a relatively good electron blocking effect, which can Electrons that do not fall into the light emitting layer 130 bounce back into the light emitting layer 130 to increase light efficiency. In addition, the thickness T1 of the first P-type AlGaN layer 142c1 is relatively thin, so the epitaxial defects caused by the high content of Al can be reduced.

In addition, the P-type doping concentration in the first P-type AlGaN layer 142c1 of this embodiment is greater than the P-type doping concentration in the second P-type AlGaN layer 142c2. Among them, more P-type doping can provide more holes, and the first P-type aluminum gallium nitride layer 142c1 is closer to the light-emitting layer 130, and the holes can easily enter the light-emitting layer 130, so that holes and electrons in the light-emitting layer 130 When they meet and bond, they are released in the form of photons.

FIG. 4 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention. Please refer to FIG. 4, the light emitting diode structure 100d of this embodiment is similar to the light emitting diode structure 100a of FIG. 142d and a P-type AlInGaN layer 144d, wherein the P-type AlInGaN layer 144d is disposed between the P-type AlInGaN layer 142d and the light emitting layer 130 . In this embodiment, the P-type AlInGaN layer 144d can alleviate the material lattice mismatch between the P-type AlGaN layer 142d and the light-emitting layer 130, and can reduce the generation of the light-emitting diode structure 100d during epitaxy. of stress.

FIG. 5 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention. Please refer to FIG. 5, the light emitting diode structure 100e of this embodiment is similar to the light emitting diode structure 100a of FIG. The gallium layer 142e1 is composed of the second P-type AlGaN layer 142e2 and the P-type AlInGaN layer 144e. The aluminum content in the first P-type AlGaN layer 142e1 is different from the Al content in the second P-type AlGaN layer 142e2. Preferably, the material of the first P-type AlGaN layer 142e1 is Al _x Ga _1-x N, wherein x is 0.09˜0.2, and the material of the second P-type aluminum gallium nitride layer 142e2 is _{AlyGa 1-y} N, wherein y is 0.01˜0.15. By utilizing the difference in aluminum content between the first P-type AlGaN layer 142e1 and the second P-type AlGaN layer 142e2, light absorption can be avoided, and problems of epitaxial defects and high resistance can be reduced at the same time. The first P-type AlGaN layer 142e1 is disposed between the second P-type AlGaN layer 142e2 and the P-type AlInGaN layer 144e, and the P-type AlInGaN layer 144e directly contacts the light-emitting layer 130 . The P-type AlInGaN layer 144e can reduce the material lattice mismatch between the first P-type AlGaN layer 142e1 and the light-emitting layer 130, and can reduce the stress generated during epitaxy of the light-emitting diode structure 100e.

FIG. 6 is a schematic cross-sectional view of a light emitting diode structure according to another embodiment of the present invention. Please refer to FIG. 6, the light emitting diode structure 100f of this embodiment is similar to the light emitting diode structure 100a of FIG. The layer 170 is disposed on the P-type semiconductor layer 140 a and is located between the P-type semiconductor layer 140 a and the P-type electrode 160 . The P-type semiconductor layer 140 a can form a good ohmic contact with the P-type electrode 160 through the transparent conductive layer 170 . Here, the material of the transparent conductive layer 170 is, for example, indium tin oxide (ITO for short), indium zinc oxide (IZO for short), zinc oxide (ZnO for short), indium tin zinc Indium tin zinc oxide (ITZO for short), aluminum tin oxide (ATO for short), aluminum zinc oxide (AZO for short) or other appropriate transparent conductive materials.

In summary, since the thickness of the P-type AlGaN layer of the present invention accounts for more than 85% of the thickness of the entire P-type semiconductor layer, it can reduce the absorption of near-UV light or blue light emitted by the light-emitting layer by the P-type semiconductor layer. In this way, the light emitting diode structure of the present invention can have better light extraction efficiency.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (13)

1. a light emitting diode construction, is characterized in that, comprising:

Substrate;

N type semiconductor layer, is configured on this substrate;

Luminescent layer, is suitable for sending main emission wavelength between the 365 how light of rice to 490 how between rice, and is configured on this n type semiconductor layer; And

P type semiconductor layer, is configured on this luminescent layer, and comprises P type aluminum gallium nitride, and wherein the thickness of this P type aluminum gallium nitride accounts for more than 85% of the thickness of this p type semiconductor layer overall.

2. light emitting diode construction according to claim 1, is characterized in that, this p type semiconductor layer is this P type aluminum gallium nitride.

3. light emitting diode construction according to claim 1, is characterized in that, this p type semiconductor layer also comprises P type gallium nitride layer, is configured on this P type aluminum gallium nitride, and the thickness of this P type gallium nitride layer accounts for less than 15% of the thickness of this p type semiconductor layer overall.

4. light emitting diode construction according to claim 1, it is characterized in that, this P type aluminum gallium nitride comprises a P type aluminum gallium nitride and the 2nd P type aluminum gallium nitride, and the aluminium content in a P type aluminum gallium nitride is different from the aluminium content in the 2nd P type aluminum gallium nitride.

5. light emitting diode construction according to claim 4, it is characterized in that, one P type aluminum gallium nitride is between the 2nd P type aluminum gallium nitride and this luminescent layer, and the aluminium content in a P type aluminum gallium nitride is greater than the aluminium content in the 2nd P type aluminum gallium nitride.

6. light emitting diode construction according to claim 5, is characterized in that, the material of a P type aluminum gallium nitride is Al _xga _1-xn, wherein x is 0.09 ~ 0.2.

7. light emitting diode construction according to claim 5, is characterized in that, the material of the 2nd P type aluminum gallium nitride is Al _yga _1-yn, y are wherein 0.01 ~ 0.15.

8. light emitting diode construction according to claim 4, is characterized in that, the thickness of the 2nd P type aluminum gallium nitride is greater than the thickness of a P type aluminum gallium nitride.

9. light emitting diode construction according to claim 4, is characterized in that, the P type doping content in a P type aluminum gallium nitride is greater than the P type doping content of the 2nd P type aluminum gallium nitride.

10. light emitting diode construction according to claim 1, is characterized in that, this p type semiconductor layer also comprises P type aluminum indium gallium nitride layer, is configured between this P type aluminum gallium nitride and this luminescent layer.

11. light emitting diode constructions according to claim 1, is characterized in that, this n type semiconductor layer is n type gallium nitride layer.

12. light emitting diode constructions according to claim 1, is characterized in that, also comprise:

N-type electrode, be configured at not by this luminescent layer on this n type semiconductor layer of covering, and to be electrically connected with this n type semiconductor layer; And

P-type electrode, is configured on this p type semiconductor layer, and is electrically connected with this p type semiconductor layer.

13. light emitting diode constructions according to claim 1, is characterized in that, also comprise:

Transparency conducting layer, is configured on this p type semiconductor layer.