Multi-quantum well LED doped with first barrier layer in active region

Abstract

The invention discloses an active region first barrier layer doped multi-quantum well LED, which belongs to the technical field of semiconductor optoelectronic devices and comprises a substrate, a GaN buffer layer, an n-type GaN layer, a quantum well first barrier layer, a multi-quantum well light-emitting layer, an electron blocking layer and a p-type GaN layer. The GaN buffer layer, the n-type GaN layer, the quantum well first barrier layer, the multi-quantum well light-emitting layer, the electron blocking layer and the p-type GaN layer are sequentially grown on the substrate, the multi-quantum well light-emitting layer comprises a plurality of quantum well layers, and the lowest quantum well first barrier layer adopts a doping structure. According to the invention, hole leakage can be effectively blocked, the electron injection efficiency is improved, the LED lightening voltage is reduced, the radiation recombination of electrons and holes is increased, and the internal quantum efficiency of the LED and the output power of light are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic devices, and particularly to a multi-quantum well LED with doping in the first barrier layer of the active region. Background Art

[0002] Light-emitting diodes (LEDs) have been widely used in the fields of lighting, display, and signal indication due to their advantages such as high photoelectric conversion efficiency, long service life, easy integration, and low driving voltage. Currently, lighting electricity accounts for 20% of the total power generation in developed countries, 10%-15% in developing countries, and about 5% in less developed regions, showing great potential for LEDs to replace traditional incandescent lamps.

[0003] The emission spectrum of GaN-based semiconductor materials covers a wide range from deep ultraviolet to mid-infrared, which gives it significant development advantages in the lighting field. However, although GaN-based LEDs have been industrialized on a large scale, their luminous efficiency is still limited by the spontaneous polarization and piezoelectric polarization effects of the material itself. These polarization effects will generate a polarization electric field in the multi-quantum well structure, leading to band deformation and triggering the quantum-confined Stark effect. As the driving current increases, the leakage current problem inside the device becomes more serious, thereby reducing the internal quantum efficiency.

[0004] Traditional LED structures use ordinary multi-quantum well light-emitting layers, and the first barrier layer in the active region is undoped. Due to the existence of heterojunctions and polarization effects, this barrier layer forms an electron blocking layer, hindering the effective injection of electrons and increasing the leakage of holes, further leading to a decrease in the internal quantum efficiency and light output efficiency. Therefore, optimizing the LED structure design and solving the efficiency problem caused by polarization effects have become the key research directions for improving the performance of GaN-based LEDs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to improve the internal quantum efficiency of the LED and the output power of light, and a multi-quantum well LED with doping in the first barrier layer of the active region is provided.

[0006] The present invention solves the above technical problems through the following technical solutions. The present invention includes a substrate, a GaN buffer layer, an n-type GaN layer, a first barrier layer of the quantum well, a multi-quantum well light-emitting layer, an electron blocking layer, a p-type GaN layer, P and N electrodes. The GaN buffer layer, n-type GaN layer, first barrier layer of the quantum well, multi-quantum well light-emitting layer, and electron blocking layer are sequentially grown on the substrate, and the multi-quantum well light-emitting layer includes multiple quantum well layers. The first barrier layer of the quantum well is an N-type doping structure, and the P and N electrodes are respectively fabricated on the p-type GaN layer and the n-type GaN layer, forming ohmic contacts.

[0007] Preferably, the quantum well light-emitting layer includes an InGaN quantum well and a GaN barrier, the InGaN quantum well and the GaN barrier are arranged alternately, the InGaN quantum well and the GaN barrier form a period pair, and the multiple quantum well light-emitting layer includes multiple period pairs. Within the same period pair, the GaN barrier is located above the InGaN quantum well.

[0008] Preferably, in the structure of the multiple quantum well light-emitting layer, the In component is 15% - 20%, the thickness of the InGaN quantum well is 1 - 3 nm, and the thickness of the GaN barrier is 10 - 16 nm.

[0009] Preferably, the first barrier layer of the active region is a doped structure, and the doping type is N-type. The N-type doping is gradient doping, the gradient direction is along the epitaxial growth direction, and the gradient value ≥ 0.

[0010] Preferably, the electron blocking layer is a p-type Al y Ga 1-y N material, where 0.1 ≤ y ≤ 0.8, and the thickness of the electron blocking layer is 20 nm.

[0011] Preferably, the substrate is a sapphire nano-patterned substrate material, and the thickness of the substrate is 100 μm.

[0012] Preferably, the GaN buffer layer is an intrinsically grown GaN material by low-temperature epitaxy, and the thickness of the GaN buffer layer is 20 - 40 nm.

[0013] Preferably, the n-type GaN layer is an n-type GaN material, and the thickness of the n-type GaN layer is 2 - 3 μm.

[0014] Preferably, the p-type GaN layer is a p-type GaN material, and the thickness of the p-type GaN layer is 150 - 300 nm.

[0015] Preferably, the P and N electrodes are respectively fabricated on the p-type GaN layer and the N-type GaN layer, and are ohmic contacts. The P and N electrodes are made of transparent materials to increase the light extraction efficiency, and the N electrode is a ring structure.

[0016] The present invention has the following advantages compared with the prior art: The first barrier layer of the active region is a doped structure, and the N-type gradient doping will introduce an additional electric field. The direction of the electric field is the same as that of the applied electric field, reducing the turn-on voltage. The effective injection barrier of electrons is reduced, improving the electron injection efficiency. At the same time, the leakage barrier of holes is increased, reducing hole leakage, and solving the problems of low electron injection efficiency and hole leakage caused by polarization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the present invention;

[0018] Figure 2 is the comparison diagram of the light output power between the present invention and the traditional structure;

[0019] Figure 3 is the comparison diagram of the IV characteristics between the present invention and the traditional structure;

[0020] Figure 4 is the energy band distribution diagram of the present invention;

[0021] Figure 5 is the energy band distribution diagram of the traditional structure.

[0022] In the figure: 1. Substrate; 2. GaN buffer layer; 3. n-type GaN layer; 4. First quantum well barrier layer; 5. Multi-quantum well light-emitting layer; 6. Electron blocking layer; 7. p-type GaN layer; 8. P electrode; 9. N electrode. Detailed implementation manners

[0023] The embodiments of the present invention will be described in detail below. The embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0024] As Figure 1 shown, this embodiment provides a technical solution: a multi-quantum well LED doped in the first quantum well barrier layer of the active region, including a substrate 1, a GaN buffer layer 2, an n-type GaN layer 3, a first quantum well barrier layer 4 of the quantum well, a multi-quantum well light-emitting layer 5, an electron blocking layer 6, and a p-type GaN layer 7. The GaN buffer layer 2, the n-type GaN layer 3, the first quantum well barrier layer 4 of the quantum well, the multi-quantum well light-emitting layer 5, the electron blocking layer 6, and the p-type GaN layer 7 are sequentially grown on the substrate 1, and the first quantum well barrier layer 4 of the quantum well is an N-type doped material.

[0025] The multi-quantum well light-emitting layer 5 includes InGaN wells and GaN barriers, the InGaN wells and the GaN barriers are alternately arranged, the InGaN wells and the GaN barriers form a period pair, and within the same period pair, the GaN barrier is located above the InGaN well. The multi-quantum well light-emitting layer 5 includes six period pairs.

[0026] In the structure of the multi-quantum well light-emitting layer 5, the In component is 15% - 20%, the thickness of the InGaN well is 2 nm, and the thickness of the GaN barrier is 13 nm.

[0027] The first quantum well barrier layer 4 of the quantum well is a doped GaN structure, the doping type is N-type, and the doping concentration is 5×10 18 , and the thickness is 13 nm.

[0028] The substrate 1 is a sapphire nano-patterned substrate material, and the thickness of the substrate 1 is 100 μm; the GaN buffer layer 2 is an intrinsically grown GaN material by low-temperature epitaxy, with a thickness of 30 nm; the n-type GaN layer 3 is an n-type GaN material, with a thickness of 2 μm and a doping concentration of 5×10 18 cm -3 ; the p-type GaN layer 7 is a p-type GaN material, with a thickness of 200 nm and a doping concentration of 3×10 17 cm -3 .

[0029] As Figure 2 shown, it is a comparison diagram of the light output power of the present invention and the traditional structure. It can be seen that the present invention can effectively improve the luminous efficiency compared with the traditional structure.

[0030] As Figure 3 shown, it is a comparison diagram of the IV characteristics of the present invention and the traditional structure. It can be seen that the present invention has a lower turn-on voltage compared with the traditional structure.

[0031] As Figure 4 , Figure 5 shown, they are respectively the energy band distribution diagrams of the present invention and the traditional structure. It can be seen that the fundamental reason for the present invention to improve the LED luminous efficiency is that the present invention effectively reduces the height of the conduction band barrier layer and increases the height of the valence band barrier, thereby improving the efficiency of injecting electrons from the N region while increasing the suppression of hole leakage.

[0032] In summary, the LED structure with a heterostructure epitaxial NIP junction multi-quantum well light-emitting layer terminal in this embodiment, its quantum well first barrier layer, by adjusting the energy band structure of this layer, further reduces the electron injection barrier and increases the height of the valence band hole barrier, solving the problem of low carrier injection efficiency caused by polarization; at the same time, it further reduces the height of the electron blocking layer barrier and improves the hole blocking efficiency.

[0033] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-quantum well LED with doping in the first barrier layer of the active region, characterized in that: It includes a substrate (1), a GaN buffer layer (2), an n-type GaN layer (3), a first quantum well barrier layer (4), a multi-quantum well light-emitting layer (5), an electron blocking layer (6) and a p-type GaN layer (7). A P electrode (8), an N electrode (9), the GaN buffer layer (2), the n-type GaN layer (3), the first quantum well barrier layer (4), the multi-quantum well light-emitting layer (5), and the electron blocking layer (6) and the p-type GaN layer (7) are sequentially grown on the substrate (1). The multi-quantum well light-emitting layer (5) includes multiple quantum well and barrier pairs. The P electrode (8) is fabricated on the p-type GaN layer (7), and the N electrode (9) is fabricated on the n-type GaN layer (3).

2. The multi - quantum well LED having a doped first barrier layer in the source region according to claim 1, wherein: The multi-quantum well light-emitting layer (5) includes InGaN quantum wells and GaN barriers. The InGaN quantum wells and GaN barriers are alternately arranged. The InGaN quantum wells and GaN barriers form a periodic pair. The multi-quantum well light-emitting layer (5) includes multiple periodic pairs. Within the same periodic pair, the GaN barrier is located at the upper end of the InGaN quantum well.

3. The multi - quantum well LED with doping in the first barrier layer of the active region according to claim 2, wherein: In the structure of the multi-quantum well light-emitting layer (5), the In component is 15% - 20%. The thickness of the InGaN quantum well is 1 - 3 nm, and the thickness of the GaN barrier is 10 - 16 nm.

4. The multi-quantum well LED with the first barrier layer doped in the active region according to claim 1, characterized in that: Compared with the traditional structure, the first quantum well barrier layer (4) uses N-type doping. The N-type doping is gradient doping, the gradient direction is along the epitaxial growth direction, and the gradient value ≥ 0.

5. The multi-quantum well LED with the first barrier layer doping in the active region according to claim 1, wherein: The electron blocking layer (6) is a p-type Al y Ga 1-y N material, where 0.1 ≤ y ≤ 0.8, and the thickness of the electron blocking layer (6) is 20 nm.

6. The LED structure with a heterojunction NIP junction multi-quantum well light-emitting layer terminal according to claim 1, characterized in that: The substrate (1) is a sapphire nano-patterned substrate material, and the thickness of the substrate (1) is 100 μm.

7. The multi - quantum well LED with doping in the first barrier layer of the active region according to claim 1, wherein: The GaN buffer layer (2) is an intrinsically grown GaN material by low-temperature epitaxy, and the thickness of the GaN buffer layer (2) is 20 - 40 nm.

8. The multi - quantum well LED with doping in the first barrier layer of the active region according to claim 1, characterized in that: The n-type GaN layer (3) is an n-type GaN material, and the thickness of the n-type GaN layer (3) is 2 - 3 μm.

9. The multi-quantum well LED with the first barrier layer of the active region doped according to claim 1, characterized in that: The p-type GaN layer (7) is a p-type GaN material, and the thickness of the p-type GaN layer (7) is 150 - 300 nm.

10. The multi-quantum well LED with the first barrier layer of the active region doped as claimed in claim 1, wherein: The P electrode (8) is fabricated on the p-type GaN layer (7) and is an ohmic contact. The N electrode (9) is fabricated on the n-type GaN layer (3) and is an ohmic contact.

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