CN102148300A - Manufacturing method of ultraviolet LED (light-emitting diode) - Google Patents

Abstract

The invention provides a method for making an ultraviolet LED, comprising the following steps: step 1: take a substrate; step 2: grow a nucleation layer and an n-type layer on the substrate in sequence; step 3: grow on the n-type layer Multi-quantum well layer; step 4: growing an electron blocking layer and a p-type layer on the multi-quantum well layer to complete the growth of the structure. The invention can solve the problem of low output power of ultraviolet LED in the method of using ultraviolet light to laser RGB fluorescent powder to generate white light in white light solid-state lighting.

Description

A kind of manufacturing method of ultraviolet LED

technical field

The invention belongs to the field of nitride-based material growth and device manufacturing, in particular to a method for manufacturing an ultraviolet LED that can improve the output power of the ultraviolet LED.

Background technique

White solid-state lighting light-emitting diodes (LEDs) are considered the third generation of lighting sources after incandescent and fluorescent lamps. Compared with traditional light sources, all-solid-state semiconductor lighting sources have a series of advantages such as high luminous efficiency, long life, small size, fast response, shock resistance, and safe use. It is a green lighting source that is environmentally friendly and energy-saving. .

At present, there are mainly three ways to realize white light solid-state lighting, and the most used one is blue LED+YAG phosphor powder. There are relatively large changes. The second is to use ultraviolet LEDs to laser RGB phosphors to produce white light. Because there is no directionality in the light emission, the color rendering index and color temperature do not change significantly with the change of operating current and operating temperature. At the same time, different RGB ratios can be obtained freely. White light with high color temperature but high color rendering index can meet different lighting needs. Based on the above advantages, this method of generating white light will become the development trend of white light LED in the future.

But there is a fatal shortcoming in this way of producing white light, that is, it cannot produce high-power ultraviolet LEDs. Whether it is a deep-ultraviolet LED based on AlGaN or a near-ultraviolet LED based on InGaN and GaN, the current output power is very low. Therefore, in order to replace the current method of blue LED+YAG phosphor with this method of generating white light, it is necessary to increase the output power of the ultraviolet LED.

One of the factors causing the low output power of UV LEDs is the lattice mismatch between AlGaN, InGaN and GaN, resulting in a high defect density of epitaxial wafers. If a material that matches the lattice of the above materials can be found, the defect density can be reduced, the piezoelectric polarization can be eliminated, and the final output power of the UV LED can be improved.

Based on the above reasons, another ternary nitride alloy AlInN is considered. The bandwidth of AlN is 6.2eV, and the bandwidth of InN is 0.7eV, so the bandgap width of AlInN has the largest adjustable range among III-nitride ternary alloy materials. When the composition of In is 0.18, the lattice constant of Al _0.82 In _0.18 N matches that of GaN, and its bandwidth is about 4.5eV. Al _0.82 In _0.18 N/GaN can be considered to replace AlGaN/GaN. After experiments and theoretical demonstrations, it was found that compared with the AlGaN/GaN structure, on the one hand, the lattice-matched Al _0.82 In _0.18 N/GaN multiple quantum wells can avoid cracks or dislocations caused by lattice mismatch; on the other hand, The bandwidth of Al _0.82 In _0.18 N at room temperature is about 4.5eV, which can prevent the band tail absorption of the barrier layer in the multiple quantum wells. Therefore, the Al _0.82 In _0.18 N/GaN structure can replace the AlGaN/GaN structure. In addition, the built-in electric field in Al _0.82 In _0.18 N/GaN single quantum well is 3.64MVcm ^-1 , which is mainly caused by spontaneous polarization, and its luminescence can cover a wide band in the ultraviolet spectrum. Therefore, the Al _0.82 In _0.18 N/GaN structure can be used as an ultraviolet light-emitting device, and the luminous efficiency at room temperature is 30 times higher than that of the corresponding AlGaN structure.

At the same time, since the lattice constant of AlInN has a large adjustable range, it can have good lattice matching with other epitaxial layers, and can also be used to prepare mismatch-free heterogeneous materials such as AlInN/InGaN and AlInN/AlGaN. structure, by adjusting different component distribution ratios, the light emitting wavelength of the LED with the two structures as the active region can be guaranteed to be in the ultraviolet range.

Furthermore, due to the good lattice matching function of AlInN, combined with its relatively wide bandgap, it can also be used as an electron blocking layer to replace the traditional AlGaN structure and improve the injection efficiency of electrons, which will eventually help To improve the output power of UV LED.

Contents of the invention

The object of the present invention is to provide a method for manufacturing ultraviolet LEDs, which can solve the problem of low output power of ultraviolet LEDs in the method of using ultraviolet light to laser RGB phosphors to produce white light in white light solid-state lighting.

In order to achieve the above object, the present invention provides a method for making an ultraviolet LED, comprising the following steps:

Step 1: Take a substrate;

Step 2: growing a nucleation layer and an n-type layer sequentially on the substrate;

Step 3: growing multiple quantum well layers on the n-type layer;

Step 4: growing an electron blocking layer and a p-type layer on the multi-quantum well layer to complete the growth of the structure.

Wherein the substrate is a sapphire substrate or a silicon substrate.

Wherein the nucleation layer is a low-temperature AlN layer or a low-temperature GaN layer, the growth temperature of the low-temperature AlN layer is 550-650°C, the growth temperature of the low-temperature GaN is 500-600°C, and the thickness of the nucleation layer is 10-50nm .

The n-type layer is a high-temperature AlGaN layer or GaN layer, wherein the growth temperature of AlGaN is 1000-1150° C., the growth temperature of GaN is 950-1100° C., and the thickness of the n-type layer is 0.5-2 μm.

Wherein the number of periods of the multi-quantum well layer is 2-10.

Wherein the multiple quantum well layer is AlInN/AlGaN, AlInN/GaN or AlInN/InGaN, wherein the thickness of the well layer is 1.0-6.0nm, and the thickness of the barrier layer is 5.0-20nm.

Wherein the electron blocking layer is an AlInN layer, its doping type is p-type, its growth temperature is 720-850° C., and its thickness is 20-50 nm.

The p-type layer is an AlGaN layer or a GaN layer, wherein the growth temperature of the AlGaN layer is 1000-1150° C., the growth temperature of the GaN layer is 950-1100° C., and the thickness of the p-type layer is 0.1-0.5 μm.

The beneficial effect of adopting the above method is that the present invention solves the current problem of low output power of ultraviolet LEDs by using AlInN material. The lattice constant of the AlInN material with an In composition of 0.18 is the same as that of GaN, but its forbidden band width is about 0.9eV higher than that of GaN. Using Al _0.82 In _0.18 N/GaN as a multiple quantum well, on the one hand, can avoid The cracks or dislocations brought by matching reduce the piezoelectric polarization; on the other hand, the bandwidth of Al _0.82 In _0.18 N at room temperature is about 4.5eV, which can prevent the band tail absorption of the barrier layer in the multiple quantum wells. In the same way, the same effect can be obtained by adjusting the composition to obtain lattice-matched AlInN/InGaN and AlInN/AlGaN multiple quantum wells. When Al _0.82 In _0.18 N is used as the electron blocking layer, it can effectively block electrons from flowing into the p-type layer, and improve the electron-hole recombination efficiency in the active region. The above methods can improve the final output power of the UV LED.

Description of drawings

In order to describe the specific content of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, wherein:

Fig. 1 is a schematic flow chart of the method of the present invention;

Fig. 2 is a structural schematic diagram of the present invention.

Detailed ways

Please refer to Fig. 1 and shown in Fig. 2, the present invention provides a kind of manufacturing method of ultraviolet LED, comprises the following steps:

Step 1: Take a substrate 1, which is a sapphire substrate or a silicon substrate;

Step 2: growing a nucleation layer 2 and an n-type layer 3 sequentially on the substrate 1, the nucleation layer 2 is a low-temperature AlN layer or a low-temperature GaN layer, wherein the growth temperature of the low-temperature AlN layer is 550-650°C, and the low-temperature GaN layer The growth temperature of layer 2 is 500-600°C, and the thickness of the nucleation layer 2 is 10-50nm; the n-type layer 3 is a high-temperature AlGaN or GaN layer, wherein the growth temperature of the AlGaN layer is 1000-1150°C, and the GaN layer The growth temperature is 950-1100° C., and the thickness of the n-type layer 3 is 0.5-2 μm;

Step 3: grow a multi-quantum well layer 4 on the n-type layer 3, the multi-quantum well layer 4 is AlInN/AlGaN, AlInN/GaN or AlInN/InGaN, the thickness of the well layer is 1.0-6.0nm, and the thickness of the barrier layer is 5.0-20nm, the number of cycles is 2-10;

Step 4: On the multi-quantum well layer 4, an electron blocking layer 5 and a p-type layer 6 are sequentially grown, the electron blocking layer 5 is an AlInN layer, the doping type is p-type, the growth temperature is 720-850°C, and the thickness is 20 -50nm; the p-type layer 6 is an AlGaN layer or a GaN layer, wherein the growth temperature of the AlGaN layer is 1000-1150°C, the growth temperature of the GaN layer is 950-1100°C, and the thickness of the p-type layer 6 is 0.1-0.5 μm, to complete the growth of the structure.

example

Please refer to Fig. 1 and Fig. 2 again, the present invention provides a kind of manufacturing method of ultraviolet LED, comprises the following steps:

Step 1: Take a sapphire substrate 1;

Step 2: growing a nucleation layer 2 and an n-type layer 3 sequentially on the substrate 1, the nucleation layer 2 is low-temperature GaN, its growth temperature is 550°C, and the thickness is 30nm; the n-type layer 3 is high-temperature GaN layer, the growth temperature is 1050°C, and the thickness is 1.5μm;

Step 3: growing a multi-quantum well layer 4 on the n-type layer 3, the multi-quantum well layer 4 is AlInN/GaN, the thickness of the well layer is 3.0nm, the thickness of the barrier layer is 12.0nm, and the number of periods is 5;

Step 4: growing an electron blocking layer 5 and a p-type layer 6 on the multi-quantum well layer 4 respectively, the electron blocking layer 5 is an AlInN layer, its doping type is p-type, the growth temperature is 800°C, and the thickness is 30nm; The p-type layer 6 is a GaN layer with a growth temperature of 1000° C. and a thickness of 0.2 μm to complete the growth of the structure.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. the manufacture method of a ultraviolet LED comprises the steps:

Step 1: get a substrate;

Step 2: on substrate, grow into stratum nucleare and n type layer successively;

Step 3: the multiple quantum well layer of on n type layer, growing;

Step 4: growth electronic barrier layer and p type layer on multiple quantum well layer, finish the growth of structure.

2. the manufacture method of ultraviolet LED according to claim 1, wherein said substrate is Sapphire Substrate or silicon substrate.

3. the manufacture method of ultraviolet LED according to claim 1, wherein said nucleating layer is low temperature AI N layer or low temperature GaN layer, the growth temperature of described low temperature AI N layer is 550-650 ℃, and the growth temperature of low temperature GaN is 500-600 ℃, and the thickness of this nucleating layer is 10-50nm.

4. the manufacture method of ultraviolet LED according to claim 1, wherein said n type layer is high temperature AlGaN layer or GaN layer, and wherein the growth temperature of AlGaN is 1000-1150 ℃, and the growth temperature of GaN is 950-1100 ℃, and the thickness of this n type layer is 0.5-2 μ m.

5. the manufacture method of ultraviolet LED according to claim 1, the periodicity of wherein said multiple quantum well layer is 2-10.

6. the manufacture method of ultraviolet LED according to claim 1, wherein said multiple quantum well layer is AlInN/AlGaN, AlInN/GaN or AlInN/InGaN, and wherein the trap layer thickness is 1.0-6.0nm, and barrier layer thickness is 5.0-20nm.

7. the manufacture method of ultraviolet LED according to claim 1, wherein said electronic barrier layer is the AlInN layer, and its doping type is the p type, and growth temperature is 720-850 ℃, and thickness is 20-50nm.

8. the manufacture method of ultraviolet LED according to claim 1, wherein said p type layer is AlGaN layer or GaN layer, and wherein the growth temperature of AlGaN layer is 1000-1150 ℃, and the growth temperature of GaN layer is 950-1100 ℃, and the thickness of this p type layer is 0.1-0.5 μ m.

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