CN109524520B - High-performance green light diode multi-quantum well structure and preparation method thereof - Google Patents

Abstract

The invention relates to a high-performance green diode multi-quantum well structure and a preparation method thereof, belonging to the technical field of semiconductor materials; the technical problem to be solved is to provide a multi-quantum well structure doped with gradient silicon in potential barrier with good crystal quality, large carrier recombination probability and high quantum luminous efficiency and a preparation method thereof; the technical proposal is as follows: the structure of the device along the growth direction is as follows: the single-group structure unit consists of an InGaN quantum well layer with fixed In component and an Si graded doped GaN barrier layer along the growth direction, the doping concentration of Si In the first Si graded doped GaN barrier layer linearly decreases along the growth direction, and the doping concentration of Si In the Si graded doped GaN barrier layer In the single-group structure unit linearly decreases along the growth direction.

Description

A high-performance green light diode multiple quantum well structure and its preparation method

Technical field

The invention is a high-performance green light diode multi-quantum well structure and its preparation method, which belongs to the technical field of semiconductor materials.

Background technique

The In component in InGaN green LED can reach about 30%, which will produce a large piezoelectric polarization effect in the quantum well. At present, conventional methods include barrier layer doping with silicon, or barrier layer gradient doping with silicon (the doping concentration gradually decreases from the first barrier at the bottom to the top). These methods can also improve the polarization effect of quantum wells to a certain extent and reduce green light. LED operating voltage. However, the effect of reducing the dislocation density at the well/barrier interface in quantum wells is not obvious. The recombination probability of multi-quantum well carriers is low and the luminous efficiency is not high. If the doping concentration of the barrier layer is too high, the barrier layer will The crystal quality deteriorates.

Contents of the invention

The invention provides a high-performance green light diode multi-quantum well structure and its preparation method, which overcomes the shortcomings of the existing technology and provides a potential barrier with good crystal quality, high carrier recombination probability and high quantum luminescence efficiency. Internal gradient silicon doped multiple quantum well structure and preparation method thereof.

In order to solve the above technical problems, the technical solution adopted by the present invention is: a high-performance green light diode multi-quantum well structure, whose structure along the growth direction is: a first Si gradient doped GaN barrier layer and a plurality of groups of sequentially stacked A single set of structural units is composed of an InGaN quantum well layer with a fixed In composition and a GaN barrier layer gradually doped with Si along the growth direction. The doping of Si in the first gradually Si-doped GaN barrier layer The concentration decreases linearly along the growth direction. In the GaN barrier layer with Si gradient doping in a single group of structural units, the Si doping concentration decreases linearly along the growth direction.

Further, the Si doping concentration in the first Si gradient doped GaN barrier layer linearly decreases from 1×10 ¹⁹ cm ^-3 to 1×10 ¹⁷ cm ^-3 along the growth direction.

Further, the thickness of the first Si gradient doped GaN barrier layer is 50 nm.

Further, the number of the structural units is 3-10 groups.

Further, the thickness of the InGaN quantum well layer with fixed In composition is 4 nm.

Further, in the GaN barrier layer with Si gradient doping in the structural unit, the initial doping concentration of Si linearly decreases from 5×10 ¹⁸ cm ^-3 to 1×10 ¹⁶ cm ^-3 along the growth direction, and the final doping concentration of Si The impurity concentration linearly decreases from 1×10 ¹⁷ cm ^-3 to 1×10 ¹⁶ cm ^-3 along the growth direction.

The above-mentioned method for preparing a high-performance green light diode multiple quantum well structure includes the following steps:

S1. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, SiH ₄ as the doping source, the growth temperature is 840°C, and the SiH ₄ flow rate is 200 sccm when starting to grow the GaN barrier layer. The doping concentration is 1×10 ¹⁹ cm ^-3 . When the growth of the GaN barrier layer ends, the SiH ₄ flow rate is 5 sccm. The doping concentration is 1×10 ¹⁷ cm ^-3 , showing a linear gradient. The growth time is 1000 s. The reaction chamber pressure is 400 mbar, that is, the first Si gradient doped GaN barrier layer with a growth thickness of 50 nm is obtained;

S2. Using triethylgallium as the gallium source, TMln as the indium source, NH ₃ as the nitrogen source, and N ₂ as the carrier gas, at a temperature of 740°C, a reaction chamber pressure of 400 mbar, and a growth time of 300 s, we obtain Grow an InGaN quantum well layer with a fixed In component in the structural unit with a thickness of 4 nm;

S3. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, SiH ₄ as the doping source, the growth temperature is 840°C, and the SiH ₄ flow rate is 150 sccm when starting to grow the GaN barrier layer. The doping concentration is 5×10 ¹⁸ cm ^-3 . When the growth of the GaN barrier layer is completed, the SiH ₄ flow rate is 5 sccm. The doping concentration is 1×10 ¹⁷ cm ^-3 , showing a linear gradient. The growth time is 350 s, that is, the result is obtained. Si gradient doped GaN barrier layer in the above structural unit;

S4. Repeat the operation of step S2;

S5. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, and SiH ₄ as the doping source. The growth temperature is 840°C. When starting to grow the GaN barrier layer, the SiH ₄ flow rate is higher than the previous time. The SiH ₄ flow rate of the growing GaN barrier layer decreases, and the lowest SiH ₄ flow rate is 5 sccm. The initial doping concentration decreases linearly compared with the initial doping concentration of the last grown GaN barrier layer. The lowest doping concentration is 1×10 ¹⁶ cm ^-3 , when the growth of the GaN barrier layer ends, the SiH ₄ flow rate is 5 sccm, and the end doping concentration decreases linearly compared with the initial doping concentration of the last grown GaN barrier layer. The minimum doping concentration is 1×10 ¹⁶ cm ^-3 . The growth time is 350 s;

S6. Repeat steps S4 and S5 to continue growing 2-9 groups of structural units.

Compared with the prior art, the present invention has the following beneficial effects.

The invention adopts a structure of gradient silicon doping within the barrier, which can not only reduce the polarization effect in the quantum well region, but also reduce the dislocation density at the well barrier interface. After growing the InGaN well layer, if you continue to grow the GaN barrier layer, a large number of dislocations will move upward. At this time, when starting to grow the barrier layer, use high-concentration silicon doping. Si atoms can break bonds with the dislocation lines. Combined, the direction of the dislocation lines is changed, thereby inhibiting the upward climbing of the dislocation lines, thereby reducing the dislocation density. As the thickness of the barrier layer increases, the dislocation density will gradually decrease. At this time, the silicon doping concentration can be reduced to avoid deterioration of crystal quality. Using the same method, as the number of barrier layers increases, the silicon concentration at which the barrier layers begin to grow can be gradually reduced. The method of gradient within the barrier layer not only reduces the polarization effect in the quantum well, but also improves the crystal quality of the quantum well, thereby achieving the purpose of improving the internal quantum efficiency.

Description of the drawings

Figure 1 is a schematic structural diagram of a high-performance green light diode provided by an embodiment of the present invention.

Figure 2 is a schematic diagram of the multi-quantum well structure of a high-performance green light diode provided by the present invention.

In the figure, 1-substrate, 2-GaN nucleation layer, 3-high temperature undoped u-GaN layer, 4-Si doped n-GaN layer, 5-multiple quantum well structure, 6-p-InAIGaN Electron blocking layer, 7-Mg doped p-GaN layer, 51-first Si gradient doped GaN barrier layer, 52-structural unit, 521-InGaN quantum well layer with fixed In composition, 522-Si gradient doping Complex GaN barrier layer.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, the present invention provides an embodiment of a high-performance green light diode multi-quantum well structure. The structure is sequentially composed along the growth direction: a first Si gradient doped GaN barrier layer 51 and three stacked GaN barriers in sequence. The structural unit 52 of the single group of structural units 52 is composed of an InGaN quantum well layer 521 with a fixed In composition and a Si gradient doped GaN barrier layer 522 along the growth direction. The first Si gradient doped GaN barrier layer 51 The doping concentration of Si linearly decreases along the growth direction. In the GaN barrier layer 522 gradually doped with Si in the single group of structural units 52, the doping concentration of Si decreases linearly along the growth direction.

The Si doping concentration in the first Si gradient-doped GaN barrier layer 51 linearly decreases from 1×10 ¹⁹ cm ^-3 to 1×10 ¹⁷ cm ^-3 along the growth direction. The thickness of the first Si graded doped GaN barrier layer 51 is 50 nm. The thickness of the InGaN quantum well layer 521 with fixed In composition is 4 nm.

In the Si gradient doped GaN barrier layer 522 in the structural unit 52, the initial doping concentration of Si linearly decreases from 5×10 ¹⁸ cm ^-3 to 1×10 ¹⁶ cm ^-3 along the growth direction, and the final doping concentration of Si Along the growth direction, it decreases linearly from 1×10 ¹⁷ cm ^-3 to 1×10 ¹⁶ cm ^-3 .

The present invention provides the above-mentioned method for preparing a high-performance green light diode multiple quantum well structure, which includes the following steps:

S1. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, SiH ₄ as the doping source, the growth temperature is 840°C, and the SiH ₄ flow rate is 200 sccm when starting to grow the GaN barrier layer. The doping concentration is 1×10 ¹⁹ cm ^-3 . When the growth of the GaN barrier layer ends, the SiH ₄ flow rate is 5 sccm. The doping concentration is 1×10 ¹⁷ cm ^-3 , showing a linear gradient. The growth time is 1000 s. The reaction chamber pressure is 400 mbar, that is, a first graded Si graded doped GaN barrier layer 51 with a growth thickness of 50 nm is obtained;

S2. Using triethylgallium as the gallium source, TMln as the indium source, NH ₃ as the nitrogen source, and N ₂ as the carrier gas, at a temperature of 740°C, a reaction chamber pressure of 400 mbar, and a growth time of 300 s, we obtain Grow an InGaN quantum well layer 521 with a fixed In composition in the graded doping structural unit 52 with a thickness of 4 nm;

S3. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, SiH ₄ as the doping source, the growth temperature is 840°C, and the SiH ₄ flow rate is 150 sccm when starting to grow the GaN barrier layer. The doping concentration is 5×10 ¹⁸ cm ^-3 . When the growth of the GaN barrier layer is completed, the SiH ₄ flow rate is 5 sccm. The doping concentration is 1×10 ¹⁷ cm ^-3 . It shows a linear gradient. The growth time is 350 s, that is, the gradient is obtained. Si gradient doped GaN barrier layer 522 in the doped structural unit 52;

S4. Repeat the operation of step S2;

S5. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, and SiH ₄ as the doping source. The growth temperature is 840°C. When starting to grow the GaN barrier layer, the SiH ₄ flow rate is higher than the previous time. The SiH ₄ flow rate of the growing GaN barrier layer decreases, and the lowest SiH ₄ flow rate is 5 sccm. The initial doping concentration decreases linearly compared with the initial doping concentration of the last grown GaN barrier layer. The lowest doping concentration is 1×10 ¹⁶ cm ^-3 , when the growth of the GaN barrier layer ends, the SiH ₄ flow rate is 5 sccm, and the end doping concentration decreases linearly compared with the initial doping concentration of the last grown GaN barrier layer. The minimum doping concentration is 1×10 ¹⁶ cm ^-3 . The growth time is 350 s;

S6. Repeat steps S4 and S5 to continue growing two gradually doped structural units 52.

As shown in Figure 2, the present invention also provides a high-performance green light diode structure, which consists of a substrate 1, a GaN nucleation layer 2, a high-temperature undoped u-GaN layer 3, and a Si-doped layer along the growth direction. Doped n-GaN layer 4, the above-mentioned multiple quantum well structure 5, p-InAIGaN electron blocking layer 6 and Mg-doped p-GaN layer 7. The present invention also provides a method for preparing a high-performance green light diode. The steps include the steps of the above-mentioned method for preparing the multiple quantum well structure 5, and further include the following steps:

(1) High-temperature cleaning treatment on the surface of patterned sapphire substrate: reduction treatment in _H2 atmosphere for 300 s at a temperature of 1070°C, and then nitriding treatment on the surface;

(2) Use trimethylgallium as the gallium source, NH ₃ as the nitrogen source, H ₂ as the carrier gas, the growth temperature is 550°C, the time is 150 s, the reaction chamber pressure is 600 mbar, the annealing temperature is 1040°C, the time is 200 s, that is, growing a GaN nucleation layer 2 with a thickness of 25 nm on the patterned sapphire substrate;

(3) Use trimethylgallium as the gallium source, NH ₃ as the nitrogen source, H ₂ as the carrier gas, the growth temperature is 1060 ℃, the growth time is 3600 s, and the reaction chamber pressure is 600 mbar, that is, in the GaN nucleation layer 2 A high-temperature undoped u-GaN layer 3 with a thickness of 2 μm was grown.

(4) Use trimethylgallium as the gallium source, SiH ₄ as the silicon source, NH ₃ as the nitrogen source, H ₂ as the carrier gas, the growth temperature is 1065 ℃, the growth time is 1800 s, and the reaction chamber pressure is 600 mbar, that is A Si-doped n-GaN layer 4 with a thickness of 1 μm is grown on a high-temperature undoped u-GaN layer 3.

(5) Use trimethylgallium as the gallium source, trimethylaluminum as the aluminum source, trimethylindium as the indium source, and magnocene as the magnesium source to achieve p-type on the uppermost GaN barrier layer of the multi-quantum well structure 5 Doping, NH ₃ is used as the nitrogen source, N ₂ is the carrier gas, the growth temperature is 920°C, the growth time is 300 s, the reaction pressure is 200 mbar, that is, the p-InAIGaN electron blocking layer 6 is 50 nm thick.

(6) Trimethylgallium is used as the gallium source, magnocene is the magnesium source, NH ₃ is used as the nitrogen source, nitrogen is the carrier gas, the growth temperature is 960 ℃, the growth time is 3000s, and the reaction chamber pressure is 200 mbar, that is, at A Mg-doped p-GaN layer 7 with a thickness of 250 nm is grown on the p-InAIGaN electron blocking layer 6, and then annealed in _an N atmosphere at a temperature of 650°C for 900 s, and then lowered to room temperature to obtain the gradient within the barrier. Doped InGaN-based multiple quantum well green light diode structure.

The main factors affecting the internal quantum efficiency of GaN-based green light diodes are the piezoelectric polarization effect and the quality of the well barrier interface. First of all, due to the polarization effect in the InGaN quantum well, especially in the green light band with high In composition, the polarization electric field generated causes the energy band in the multi-quantum well to bend, and the conduction band is lower on the p-type side, and the n-type one The side is raised, so that the band edge of the multi-quantum well changes from a square to a triangle, the baseband energy of the conduction band decreases, and the baseband energy of the valence band increases, narrowing the gap width between the two, resulting in a red shift of the luminescence wavelength. further affect the luminous efficiency. At the same time, the tilt of the energy band will also make it easier for carriers to cross the potential barrier, causing carrier leakage. Therefore, the polarization effect of InGaN green light quantum well is one of the main factors affecting the photoelectric performance of green light diodes. Secondly, the interface quality of the well barrier in the quantum well also seriously affects the improvement of the internal quantum efficiency. When the high-In composition InGaN well layer is grown, the well barrier material has a large lattice mismatch, which will generate a large number of single-atom or multi-atom edge dislocations at the well/barrier interface, thus reducing the electron transfer rate. The transport capacity will increase the probability of non-radiative recombination in the quantum well region, thereby reducing the internal quantum efficiency. The growing GaN barrier layer is doped with silicon atoms, which can bend the dislocation lines, thereby inhibiting the dislocation lines from continuing to climb upward and improving the crystal quality of the well barrier interface.

The invention adopts gradient doping within the barrier to reduce the polarization effect of the quantum well. Gradient doping of silicon within the barrier layer can reduce the dislocation density in the quantum well, thereby greatly improving the internal quantum efficiency of the green light diode quantum well. At the same time, , also reduces the leakage of carriers, thereby improving the photoelectric performance of green light diodes.

Although the invention has been specifically shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that changes may be made in form and detail without departing from the spirit and scope of the invention as defined by the claims. various changes on.

Claims (7)

1. A high-performance green light diode multiple quantum well structure, characterized in that its structure consists of: a first Si gradient doped GaN barrier layer (51) and multiple groups of sequentially stacked structural units (51) along the growth direction. 52), a single set of structural units (52) consists of an InGaN quantum well layer (521) with a fixed In composition and a Si gradient doped GaN barrier layer (522) along the growth direction. The first Si gradient doped GaN The Si doping concentration in the barrier layer (51) linearly decreases along the growth direction, and in the GaN barrier layer (522) with Si gradient doping in the single group of structural units (52), the Si doping concentration linearly decreases along the growth direction. 2. A high-performance green light diode multiple quantum well structure according to claim 1, characterized in that: the Si doping concentration in the first Si gradient doped GaN barrier layer (51) is along the growth direction. , linearly decreasing from 1×10 ¹⁹ cm ^-3 to 1×10 ¹⁷ cm ^-3 . 3. A high-performance green light diode multiple quantum well structure according to claim 1, characterized in that: the thickness of the first Si gradient doped GaN barrier layer (51) is 50 nm. 4. A high-performance green light diode multiple quantum well structure according to claim 1, characterized in that: the number of the structural units (52) is 3-10 groups. 5. A high-performance green light diode multiple quantum well structure according to claim 1, characterized in that: the thickness of the InGaN quantum well layer (521) with fixed In composition is 4 nm. 6. A high-performance green light diode multiple quantum well structure according to claim 1, characterized in that: the Si gradient doped GaN barrier layer (522) in the structural unit (52), the initial Si The doping concentration linearly decreases from 5×10 ¹⁸ cm ^-3 to 1×10 ¹⁶ cm ^-3 along the growth direction. The end doping concentration of Si decreases linearly from 1×10 ¹⁷ cm ^-3 to 1×10 along the growth direction. ¹⁶ cm ^-3 . 7. A method for preparing a high-performance green light diode multiple quantum well structure according to any one of claims 1-6, characterized by comprising the following steps: S1. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, SiH ₄ as the doping source, the growth temperature is 840°C, and the SiH ₄ flow rate is 200 sccm when starting to grow the GaN barrier layer. The doping concentration is 1×10 ¹⁹ cm ^-3 . When the growth of the GaN barrier layer ends, the SiH ₄ flow rate is 5 sccm. The doping concentration is 1×10 ¹⁷ cm ^-3 , showing a linear gradient. The growth time is 1000 s. The reaction chamber pressure is 400 mbar, that is, the first Si gradient doped GaN barrier layer (51) with a growth thickness of 50 nm is obtained; S2. Using triethylgallium as the gallium source, TMln as the indium source, NH ₃ as the nitrogen source, and N ₂ as the carrier gas, at a temperature of 740°C, a reaction chamber pressure of 400 mbar, and a growth time of 300 s, we obtain Growing an InGaN quantum well layer (521) with a fixed In composition in the structural unit (52) with a thickness of 4 nm; S3. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, SiH ₄ as the doping source, the growth temperature is 840°C, and the SiH ₄ flow rate is 150 sccm when starting to grow the GaN barrier layer. The doping concentration is 5×10 ¹⁸ cm ^-3 . When the growth of the GaN barrier layer is completed, the SiH ₄ flow rate is 5 sccm. The doping concentration is 1×10 ¹⁷ cm ^-3 , showing a linear gradient. The growth time is 350 s, that is, the result is obtained. the Si graded doped GaN barrier layer (522) in the structural unit (52); S4. Repeat the operation of step S2; S5. Use triethylgallium as the gallium source, NH ₃ as the nitrogen source, N ₂ as the carrier gas, and SiH ₄ as the doping source. The growth temperature is 840°C. When starting to grow the GaN barrier layer, the SiH ₄ flow rate is higher than the previous time. The SiH ₄ flow rate of the growing GaN barrier layer decreases, and the lowest SiH ₄ flow rate is 5 sccm. The initial doping concentration decreases linearly compared with the initial doping concentration of the last grown GaN barrier layer. The lowest doping concentration is 1×10 ¹⁶ cm ^-3 , when the growth of the GaN barrier layer ends, the SiH ₄ flow rate is 5 sccm, and the end doping concentration decreases linearly compared with the initial doping concentration of the last grown GaN barrier layer. The minimum doping concentration is 1×10 ¹⁶ cm ^-3 . The growth time is 350 s; S6. Repeat steps S4 and S5 to continue growing 2-9 groups of the structural units (52).