CN101452980B - Production method of group III nitride compound semiconductor LED - Google Patents

Abstract

The invention provides a three-group nitrogen-compound semiconductor LED, which comprises a substrate, a buffer layer, an N-type semiconductor material layer, conformation active layers and a P-type semiconductor material layer, wherein the N-type semiconductor material layer has a first surface and a second surface; the first surface is in direct contact with the buffer layer; the second surface has a plurality of concave parts; the conformation active layers are formed on the second surface and in the concave parts; and the stress between the conformation active layers and the N-type semiconductor material layer can be released through the concave parts.

Description

Manufacturing method of Group III nitrogen compound semiconductor light-emitting diode

technical field

The invention relates to a group III nitrogen compound semiconductor light emitting diode and its manufacturing method, in particular to a group III nitrogen compound semiconductor light emitting diode capable of releasing stress between an active layer and an N-type semiconductor material layer and its manufacturing method. the

Background technique

As light-emitting diode elements are widely used in different products, in recent years, materials for making blue light-emitting diodes have become an important research and development object in the current optoelectronic semiconductor material industry. At present, the materials of blue light-emitting diodes include zinc selenide (ZnSe), silicon carbide (SiC) and indium gallium nitride (InGaN) and other materials. These materials are semiconductor materials with a wide band gap, and the band gap is about 2.6 above eV. Since the gallium nitride series is a luminescent material with a direct gap, it can produce high-brightness illumination light, and has the advantage of longer life than zinc selenide, which is also a direct gap. the

At present, the active layer (light-emitting layer) of blue light-emitting diodes mostly adopts an indium gallium nitride/gallium nitride (InGaN/GaN) quantum well structure, and the quantum well structure is sandwiched between an N-type gallium nitride (GaN) layer and a P type between GaN layers. When In is added to GaN to form InGaN, due to the difference in lattice constant between InGaN and GaN, the interface between the active layer and gallium nitride produces stress. The stress will produce a piezoelectric effect to form a piezoelectric field, which will affect the luminous efficiency and wavelength of the active layer, so it is necessary to eliminate the stress to avoid adverse effects. the

FIG. 1 is a schematic cross-sectional view of a light emitting diode in US Pat. No. 6,345,063. The light emitting diode 10 includes a substrate 11, a buffer layer 12, an N-type InGaN layer 13, an active layer 14, a first P-type III-V nitrogen compound layer 15, a second P-type III-V nitrogen compound layer 16, and a P-type electrode 17 and N-type electrode 18. Lattice constants are matched between the N-type InGaN layer 13 and the InGaN film of the active layer 14, so accumulated stress can be eliminated. However, the formation temperature of the N-type InGaN layer 13 is relatively low, so the quality of the crystal epitaxial growth will be sacrificed to replace the original GaN layer with better quality. the

FIG. 2 is a schematic cross-sectional view of a light emitting diode in US Pat. No. 6,861,270. The light emitting diode 20 includes a substrate 21 , an N-type aluminum gallium nitride (AlGaN) layer 22 , a plurality of gallium or aluminum micro-protrusions 25 , an active layer 23 and a P-type aluminum gallium nitride layer 24 . The gallium micro-protrusions 25 will cause fluctuations in the energy gap of the active layer 23, and the luminous efficiency in the region with a narrower energy gap will increase, even if dislocations (dislocation) still occur in the region. See the Summary of the Invention of the US patent, which clearly discloses that the fluctuation of the energy gap band is caused by the difference in the lattice constant, so this patent does not solve the stress problem caused by the mismatch of the lattice constant. the

FIG. 3 is a schematic cross-sectional view of a light emitting diode of US Pat. No. 7,190,001. The light emitting diode 30 comprises a substrate 31, a buffer layer 32, an N-type cladding layer (cladding layer) 33, an AlN uneven layer 34, an active layer 35, a P-type cladding layer 36, a contact layer 37, a transparent electrode 38, and a P-type electrode 391 and an N-type electrode 392 . The active layer 35 is formed on the AlN non-planar layer 34, so the growth conditions of the active layer 35 can be simplified, thereby increasing the luminous efficiency. However, the AlN non-planar layer 34 needs a special heat treatment process to be formed on the N-type cladding layer 33 , so it is easy to affect the quality of the epitaxial crystal growth of the original bottom layer. the

To sum up, there is an urgent need for a light-emitting diode with stable quality in the market, so as to improve the various shortcomings of the above-mentioned conventional technologies. the

Contents of the invention

The main purpose of the present invention is to provide a kind of Group III nitrogen compound semiconductor light-emitting diode and its manufacturing method, it can reduce the stress accumulation of crystal epitaxial growth layer, thereby can reduce Quantum Confined Stark Effect (Quantum Confined Stark Effect; QCSE), increase electron And hole recombination probability, thereby improving the luminous efficiency of light-emitting diodes. the

To achieve the above purpose, the present invention discloses a Group III nitrogen compound semiconductor light-emitting diode, which includes a substrate, a first-type semiconductor material layer, a conformation (conformation) active layer, and a second-type semiconductor material layer. The first-type semiconductor material layer includes a first surface and a second surface, wherein the first surface faces the substrate, and the second surface is opposite to the first surface and has a plurality of recesses. The conformal active layer is formed on the second surface and within the plurality of recesses. Stress between the conformal active layer and the first type semiconductor material layer can be released through the plurality of recesses. The second type semiconductor material layer is disposed on the conformal active layer. the

The above light emitting diode further includes a buffer layer between the substrate and the first type semiconductor material layer. the

The depth of the recess is larger than the thickness of the quantum well layer in the conformal active layer and smaller than the thickness of the first type semiconductor material layer. And the width of the upper opening of the concave part is greater than 0.1 μm and less than 10 μm. The plurality of recesses have different sizes. The plurality of recesses with different sizes are uniformly or staggeredly distributed. The opening width of the recess is larger than the bottom width of the recess. the

The conformal active layer is a single-layer quantum well structure or a multi-layer quantum well structure. the

The first-type semiconductor material layer is an N-type semiconductor material layer, and the second-type semiconductor material layer is a P-type semiconductor material layer. the

The present invention also discloses a method for manufacturing a Group-III nitrogen compound semiconductor light-emitting diode, comprising the following steps: providing a substrate; growing a first-type semiconductor material layer on the substrate, wherein the first-type semiconductor material layer includes a first-type semiconductor material layer A surface and a second surface, the first surface is facing the substrate, the second surface is opposite to the first surface and has a plurality of recesses; growing a conformal active layer on the first type semiconductor material layer and forming a second type semiconductor material layer on the conformal active layer. the

The plurality of recesses are formed on the second surface of the first-type semiconductor material layer through an etching process. the

The plurality of recesses are cavities formed on the second surface by controlling the flow of nitrogen, ammonia, hydrogen, trimethylgallium, triethylgallium, trimethylindium, triethylindium or organometallic compounds . The plurality of recesses are produced by a metal organic chemical vapor deposition process. the

The above manufacturing method additionally includes the step of forming at least one buffer layer directly on the surface of the substrate. the

Through the above design, the surface of the first-type semiconductor material layer of the present invention has a plurality of recesses, and the conformal active layer is formed on the surface and in the plurality of recesses. Therefore, the stress between the conformal active layer and the first-type semiconductor material layer can be released through the plurality of recesses, thereby increasing the recombination probability of electrons and holes, so as to improve the luminous efficiency of the light emitting diode. the

Description of drawings

Fig. 1 is a schematic cross-sectional view of a light-emitting diode of the U.S. Patent No. US6,345,063;

Fig. 2 is a schematic cross-sectional view of a light-emitting diode of the U.S. Patent No. US6,861,270;

Fig. 3 is a schematic cross-sectional view of a light-emitting diode of the U.S. Patent No. US7,190,001;

Fig. 4 is a schematic cross-sectional view of a group III nitrogen compound semiconductor light-emitting diode of the present invention;

Figure 5A is a partial cross-sectional schematic view of a light emitting diode of the present invention; and

FIG. 5B is a top view of part of the LEDs in FIG. 5A. the

Detailed ways

FIG. 4 is a schematic cross-sectional view of a III-nitride semiconductor light-emitting diode of the present invention. The light-emitting diode 40 includes a substrate 41, a buffer layer 42, an N-type (or called first-type) semiconductor material layer 43, a conformal active layer 44, and a P-type (or called second-type) semiconductor material layer 45. An N-type electrode 47 is provided on the surface of the N-type semiconductor material layer 43 , and a P-type electrode 46 is provided on the surface of the P-type semiconductor material layer 45 . the

Generally speaking, to fabricate the light emitting diode 40, a substrate 41 is firstly provided, such as: sapphire (ie aluminum oxide Al ₂ O ₃ ), silicon carbide (SiC), silicon, zinc oxide (ZnO), magnesium oxide (MgO) and Gallium Arsenide (GaAs) etc., and different material layers are formed on the substrate 41 . Because the substrate 41 does not match the lattice constant of the III-group nitrogen compound, it is necessary to form at least one buffer layer 42 on the substrate 41 earlier. The material of the buffer layer 42 can be GaN, InGaN or AlGaN, or the hardness is higher than conventional A superlattice (Superlattice) layer with a low buffer layer containing aluminum elements. Then an N-type semiconductor material layer 43 is grown on the buffer layer 42 , which can be used as an N-type semiconductor material layer 43 to produce an N-type gallium nitride-doped silicon thin film by crystal epitaxial growth. The upper surface of the N-type semiconductor material layer 43 is not flat, but includes a plurality of recesses 431 and a flat area 432 . The formation of the concave portion 431 can still be completed in a metal organic chemical vapor deposition (MOCVD) furnace, which is after the N-type semiconductor material layer 43 is deposited to a certain thickness (1-5 μm), and then the supplied nitrogen, ammonia, hydrogen, Trimethylgalliaum (TMGa), triethylgallium, trimethylindium (TMIn), triethylindium, or organometallic compounds are turned off or reduced to low flow, so the crystalline epitaxial growth portion of the surface generates a lot of hollow recess 431 . In addition, after the N-type semiconductor material layer 43 is formed, the same recess 431 can be formed on the surface of the N-type semiconductor material layer 43 by an etching process.

Then grow a single-layer quantum well (single quantum well; SQW) structure or a conformal active layer 44 of a multiquantum well (multiquantum well; MQW) structure on the N-type semiconductor material layer 43, for example: two to thirty layers The multi-layer quantum well stack structure of the light emitting layer/barrier layer, and the stack structure of six to eighteen layers is preferred, and the conformal active layer 44 is the part where the light emitting diode 40 mainly generates light . The light-emitting layer may be aluminum indium gallium nitride (Al _X In _Y Ga _1-XY N) and the barrier layer may be aluminum indium gallium nitride (Al _I In _J Ga _1-IJ N), and 0≤X<1 , 0≤Y<1, 0≤I<1 and 0≤J<1, X+Y<1 and I+J<1; and when X, Y, I, J>0, then X≠I and Y≠ J. Indium gallium nitride (InGaN)/gallium nitride (GaN) can also be used as the material of the light emitting layer/blocking layer. Through the recess 431 on the surface of the N-type semiconductor material layer 43 , the stress between the conformal active layer 44 and the N-type semiconductor material layer 43 can be released, so the luminous efficiency of the conformal active layer 44 can be increased. In addition, because the recess 431 is formed on the N-type semiconductor material layer 43, there is no need to add crystal epitaxial growth layers of different materials or deposit metal micro-protrusions, so the quality of each crystal epitaxial growth layer at the bottom will not be reduced. It is necessary to use a crystal epitaxial growth layer whose lattice constant matches but sacrifices the quality of crystal epitaxial growth as the N-type semiconductor material layer 43 .

At least one P-type semiconductor material layer 45 is formed on the conformal active layer 44, and the P-type semiconductor material layer 45 can be a stack of magnesium-doped gallium nitride and indium gallium nitride or magnesium-doped aluminum nitride Different structures such as gallium and gallium nitride superlattice structure plus magnesium doped gallium nitride. In addition, patterns of N-type electrodes 47 and P-type electrodes 46 are respectively formed on the N-type semiconductor material layer 43 and the P-type semiconductor material layer 45 , so that external power can be connected. the

FIG. 5A is a schematic partial cross-sectional view of a light emitting diode of the present invention. A buffer layer 42 and an N-type semiconductor material layer 43 are sequentially formed on the substrate 41 , and the surface of the N-type semiconductor material layer 43 has a plurality of recesses 431 and a flat region 432 . The depth h of the concave portion 431 may be larger than the thickness of the single quantum well layer, and smaller than the thickness of the N-type semiconductor material layer 43 . In addition, the cross section of the concave portion 431 is slightly inverted trapezoidal, and the width W of the opening above it may be greater than 0.1 μm and less than 10 μm. the

FIG. 5B is a top view of part of the LEDs in FIG. 5A. The width W or diameter of the plurality of recesses 431 is not uniform but different in size, and the recesses 431 of different sizes are approximately evenly or alternately distributed on the surface of the N-type semiconductor material layer 43 . the

The technical content and technical features of the present invention have been disclosed above, but those skilled in the art may still make various replacements and modifications based on the teaching and disclosure of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to the scope disclosed in the embodiments, but should include various replacements and modifications that do not depart from the present invention, and are covered by the appended claims. the

Claims (13)

1. the manufacturing approach of an III-family nitrogen compound semiconductor light-emitting diode is characterized in that comprising the following step:

Substrate is provided;

Growth first type semiconductor material layer on said substrate; Wherein said first type semiconductor material layer comprises first surface and second surface; Said first surface is towards said substrate; Said second surface is with respect to said first surface and have a plurality of recesses, and said a plurality of recesses are that organo-metallic compound that grows up to through said first type semiconductor material layer of control supply or the flow of controlling nitrogen, ammonia, hydrogen, trimethyl gallium, triethyl-gallium, trimethyl indium or triethylindium form;

Grow conformal active layer on said first type semiconductor material layer; And

On said conformal active layer, form second type semiconductor material layer.

2. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1 is characterized in that said a plurality of recess is to produce through metal organic chemical vapor deposition technology.

3. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1 is characterized in that the thickness of said concave depth greater than quantum well layer in the said conformal active layer, and less than the thickness of said first type semiconductor material layer.

4. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1, the width of top opening that it is characterized in that said recess is greater than 0.1 μ m and less than 10 μ m.

5. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1 is characterized in that said a plurality of recess has different size.

6. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 5, the recess that it is characterized in that said a plurality of different sizes is evenly or is interspersed.

7. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1 is characterized in that the bottom width of the A/F of said recess greater than said recess.

8. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1 is characterized in that said conformal active layer is individual layer quantum well structure or multi-layer quantum well structure.

9. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 8 is characterized in that said multi-layer quantum well structure is the laminated construction of luminescent layer/electricity barrier layer of two layers to 30 layers.

10. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 8 is characterized in that said multi-layer quantum well structure is the laminated construction of luminescent layer/electricity barrier layer of six layers to 18 layers.

11. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 10 is characterized in that said luminescent layer/electricity barrier layer is aluminum indium nitride gallium (Al _XIn _YGa _1-X-YN)/aluminum indium nitride gallium (Al _IIn _JGa _1-I-JN), wherein 0≤X＜1,0≤Y＜1,0≤I＜1 and 0≤J＜1, X+Y＜1 and I+J＜1; Again as X, Y, I, J＞0, then X ≠ I and Y ≠ J.

12. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1; It is characterized in that comprising in addition the resilient coating between said substrate and said first type semiconductor material layer; The material of said base material is sapphire, carborundum, silicon, zinc oxide, magnesia or GaAs, and is InGaN/gallium nitride in said luminescent layer/electricity barrier layer.

13. the manufacturing approach of III-family nitrogen compound semiconductor light-emitting diode according to claim 1; It is characterized in that said first type semiconductor material layer is the N type semiconductor material layer; And said second type semiconductor material layer is the P type semiconductor material layer; Said first type semiconductor material layer is the n type gallium nitride doped silicon film; Said second type semiconductor material layer is the magnesium-doped gallium nitride and the lamination of InGaN, or magnesium-doped aluminium gallium nitride alloy and gallium nitride superlattice structure add the lamination of magnesium-doped gallium nitride, and comprises the first type electrode and the second type electrode in addition; The wherein said first type electrode is arranged on said first type semiconductor material layer, and the said second type electrode is arranged on said second type semiconductor material layer.

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