CN1316567C

CN1316567C - Preparation f green light fallium nitride base LED epitaxial wafer by adopting multiquantum well

Info

Publication number: CN1316567C
Application number: CNB031189555A
Authority: CN
Inventors: 何清华; 刘明德; 邓纲; 熊建明
Original assignee: China Fangda Group Co Ltd
Current assignee: Shenzhen Fangda Guoke Optical Electronic Technology Co., Ltd.
Priority date: 2003-04-16
Filing date: 2003-04-16
Publication date: 2007-05-16
Anticipated expiration: 2023-04-16
Also published as: CN1460729A

Abstract

The present invention provides a green GaN-base LED epitaxial wafer prepared by a multi-quantum well. The present invention adopts a new multi-quantum well technique with a well/intermediate layer/barrier structure and utilizes an MOCVD method to grow the green GaN-base LED epitaxial wafer, wherein the intermediate layer between the well and the barrier can effectively reduce the decomposition of InGaN, and can synthesize high quality InGaN with a high In content at higher growth temperatures.

Description

Adopt Multiple Quantum Well to prepare the green LED epitaxial slice growing method of GaN base

Technical field

The present invention relates to the epitaxial growth method of a kind of gallium nitride and compound film thereof, particularly adopt green glow gallium nitride based LED (light-emitting diode) the epitaxial wafer manufacturing technology of a kind of trap/intermediate layer/novel Multiple Quantum Well of base structure.

Background technology

Having wide direct band gap, strong chemical bond, premium properties such as high temperature resistant, anticorrosive based on the III-V group nitride material of GaN, InGaN, AlGaN alloy, is to make short wavelength's high brightness luminescent device, ultraviolet light detector and high temperature, the microelectronic ideal material of high frequency.The energy gap of GaN is 3.4eV, its recombination luminescence is positioned at ultraviolet, therefore in visible light opto-electronic device with the preparation of GaN base, must use InGaN to make active layer, InGaN is Multiple Quantum Well indigo plant, green, active layer material that purple LED is desirable, can be by regulating the emission wavelength that In content change epitaxial wafer.With the variation of In molar constituent, the energy gap of InGaN material can be at 1.95eV to the 3.40eV range regulation.

See document K.Osamura according to Osamura[, K.Nakajima and Y.Murakami, Solid StateCommun., 1972,11:617-621] etc. the report In _xGa _1-xN alloy energy gap is to the dependence of In component:

E(x)＝xE _InN+(1-x)E _GaN-bx(1-x)

In the above-mentioned formula, E (x) is In _xGa _1-xThe N energy gap; X is the In degree, E _InNFor the InN energy gap, equal 2.07eV; E _GaNFor the GaN energy gap, equal 3.40eV; B is a constant, equals 1.0eV (actual b and x are functional relation).Can push away it according to this formula, the preparation emission wavelength is the green glow GaN-based LED epitaxial wafer of 525nm (energy gap 2.36eV), In _xGa _1-xThe In component of N should be greater than 0.2.Yet the decomposition temperature of In is lower, InN has high saturated vapour pressure, In atomic ratio Ga atom is difficult to enter hexagoinal lattice, therefore, its In component of InGaN of higher temperature growth is low, and low-temperature epitaxy can obtain higher In component, but its luminescent properties degenerates, luminous intensity dies down, and drips and attempt will to cause crystalline quality to reduce even also can form In on the surface with the way that improves the TMIn flow.

Adopt MOCVD technology technology be difficult to the to grow InGaN film of higher In component (x＞0.2) and various better performances routinely, and high In content and high-quality InGaN are the bases that guarantees green glow GaN base LED epitaxial wafer.

Summary of the invention

The objective of the invention is to overcome the deficiency that adopts conventional quantum well structure growing InGaN film, a kind of manufacture method of high brightness green glow GaN-based LED epitaxial wafer is provided.

Technical scheme of the present invention is: the present invention adopts MOCVD (metal organic source chemical gas-phase deposition system) equipment, high-purity H ₂, N ₂As carrier gas, whole growth pressure is controlled at the 76-780 torr, at first with Sapphire Substrate (the exempt from clean) reactor of packing into of (0001) orientation, at H ₂Under the atmosphere, be heated to more than 1050 ℃ and toasted 20 seconds; Then at the GaN of 500-600 ℃ of growth thickness 10-40nm resilient coating; Then at the GaN layer of 950-1100 ℃ of growth thickness 0.5-2 μ m and the GaN:Si layer of thickness 0.5-4 μ m; On the GaN:Si layer, at 700-900 ℃ N ₂The multiple quantum well layer in growth 3-10 cycle under the atmosphere; Then at the GaN layer of 950-1100 ℃ of growth thickness 0.1-0.5 μ m: the Mg layer; After whole outer layer growth is finished, epitaxial wafer is sent into annealing furnace, at N ₂Annealed 10-60 minute in 600-850 ℃ under the atmosphere.

Ga of the present invention, In, Mg, N, the Si source is respectively high-purity trimethyl gallium (TMGa), trimethyl indium (TMIn), two luxuriant magnesium (Cp ₂Mg), ammonia (NH ₃) and silane (SiH ₄), SiH wherein ₄Concentration is 100ppm, uses H ₂Dilution.

The pressure of growing GaN resilient coating is the 350-780 torr, carrier gas flux be the 10-30 liter/minute, the TMGa flow be the 20-120 micromole/minute, NH ₃Flow be the 20-80 micromole/minute.

The pressure of growing GaN and GaN:Si layer is the 76-250 torr, carrier gas flux be the 5-20 liter/minute, the TMGa flow be the 80-400 micromole/minute, NH ₃Flow be the 200-800 micromole/minute, the Si amount of mixing of GaN:Si layer for the 0.2-2.0 nanomole/minute.

The growth pressure of Multiple Quantum Well is the 100-400 torr, carrier gas flux be the 5-20 liter/minute, NH ₃Flow is the 200-800 moles/min.The trap layer: thickness is 1.0-6.0nm, and growth temperature is 700-800 ℃, the TMG flow be the 0.2-1.0 micromole/minute, the TMIn flow be the 10-50 micromole/minute; The intermediate layer: thickness is 0.5-3.0nm, and growth temperature is 750-850 ℃, TMGa be the 0.5-2.0 micromole/minute, TMIn be the 1-10 micromole/minute; Build layer: thickness is 5.0-20nm, and growth temperature is 800-900 ℃, TMGa be the 10-50 micromole/minute.

Growing GaN: the pressure of Mg layer is the 76-250 torr, carrier gas flux be the 5-20 liter/minute, the TMGa flow be the 80-400 micromole/minute, NH ₃Flow be the 200-800 micromole/minute, the Mg amount of mixing of GaN:Mg for the 0.5-5.0 micromole/minute.

Advantage of the present utility model is: during trap layer InGaN growth, growth temperature is lower than builds about 150 ℃ of layer GaN, as quantum well technology routinely, the trap course build layer excessively the time because the rising of temperature, to cause the decomposition of InGaN, take to reduce growth temperature and can cause that with the mode that improves the TMI flow luminous intensity sharply descends, crystal mass variation and may be split into In on the surface and drip.The present invention is by adding an intermediate layer between trap layer and base layer, in being warming up to base layer growth temperature process, this intermediate layer can effectively reduce the decomposition of InGaN, can realize under higher growth temperature that high In content and high-crystal quality InGaN are synthetic, obtain the high brightness green emission of dominant wavelength at 500-540nm.

Description of drawings

Fig. 1 epitaxial slice structure schematic diagram;

Fig. 2 green glow GaN base LED epitaxial wafer PL spectrum;

Fig. 3 green glow GaN base LED epitaxial wafer (0002) face X ray double crystal diffraction figure.

Embodiment

Adopt 6 * 2 CCS-MOCVD (Thomas Swan Scientific Equipment Ltd.) equipment, will (0001) be orientated and exempt to clean the Sapphire Substrate reactor of packing into, at H ₂Be heated to 1080 ℃ of bakings 20 minutes under the atmosphere; Reactor pressure is 100 torrs.2) the GaN resilient coating that is 30nm at 550 ℃ of growth thickness, the pressure of growing GaN resilient coating is 400 torrs, carrier gas flux is 25 liters/minute, the TMGa flow be 65 micromoles/minute, NH ₃Flow is 60 moles/min.3) the GaN:Si layer of the GaN layer of 1050 ℃ of growth thickness 1.0 μ m and 2.5 μ m, the pressure of growing GaN and GaN:Si is 150 torrs, carrier gas flux is 15 liters/minute, the TMGa flow be 200 micromoles/minute, NH ₃Flow is 600 moles/min, the Si amount of mixing of GaN:Si layer be 1.0 nanomoles/minute, 4) at N ₂The multiple quantum well layer in 8 cycles of growth under the atmosphere, growth pressure is 400 torrs, carrier gas flux is 15 liters/minute, NH ₃Flow is 600 moles/min, the trap layer: thickness is 4.0nm, and growth temperature is 740 ℃, the TMGa flow be 0.5 micromole/minute, the TMIn flow be 20 micromoles/minute; The intermediate layer: thickness is 1.0nm, and growth temperature is 800 ℃, TMGa be 1.0 micromoles/minute.TMIn be 5.0 micromoles/minute; GaN build the layer: thickness is 15nm, and growth temperature is 860 ℃, TMGa be 30 micromoles/minute.5) at the GaN:Mg layer of 1030 ℃ of growth thickness, 0.25 μ m, growing GaN: the pressure of Mg layer is 150 torrs, and carrier gas flux is 17 liters/minute, the TMGa flow be 150 micromoles/minute, NH ₃Flow is 500 moles/min, Cp ₂The Mg flow be 3.0 micromoles/minute.6) at N ₂N annealed 40 minutes in 800 ℃ under the atmosphere ₂Flow is 2.0 liters/minute.

Claims

1, a kind of employing Multiple Quantum Well prepares GaN base green light LED epitaxial wafer growth method, adopts metal organic source chemical gas-phase deposition system equipment, high-purity H ₂, N ₂As carrier gas, whole growth pressure is controlled at the 76-780 torr, and growth step is as follows: Multiple Quantum Well is trap layer/intermediate layer/base layer structure, and quantum well is InGaN layer/InGaN layer/GaN layer,

1) the 0001 orientation Sapphire Substrate reactor of packing into is at H ₂Be heated under the atmosphere more than 1050 ℃ and toasted 20 fens;

2) at the GaN of 500-600 ℃ of growth thickness 10-40nm resilient coating;

3) at the GaN layer of 950-1100 ℃ of growth thickness 0.5-2 μ m;

4) the GaN layer of 950-1100 ℃ of growth thickness 0.5-4 μ m: Si layer;

5) at 700-900 ℃ of growth multiple quantum well layer;

6) at the GaN layer of 950-1100 ℃ of growth thickness 0.1-0.5 μ m: the Mg layer;

7) at N ₂Annealed 10-60 minute in 600-850 ℃ under the atmosphere.

2, employing Multiple Quantum Well according to claim 1 prepares GaN base green light LED epitaxial wafer growth method, it is characterized in that: the growth temperature in quantum well intermediate layer is between trap layer, base layer growth temperature.

3, employing Multiple Quantum Well according to claim 1 and 2 prepares GaN base green light LED epitaxial wafer growth method, it is characterized in that: the trap layer thickness is 1.0-6.0nm, intermediate layer thickness is 0.5-3.0nm, and barrier layer thickness is 5.0-20nm, and the cycle of Multiple Quantum Well is 3-10.

4, employing Multiple Quantum Well according to claim 1 and 2 prepares GaN base green light LED epitaxial wafer growth method, it is characterized in that: trap laminar flow amount: TMGa be the 0.2-1.0 micromole/minute, TMIn be the 10-50 micromole/minute; Intermediate layer: TMGa be the 0.5-2.0 micromole/minute, TMIn be the 1-10 micromole/minute; Build layer: TMGa and be the 10-50 micromole/minute; Above-mentioned three layers of used carrier gas are N ₂, its flow be the 5-20 liter/minute, NH ₃Flow be the 200-800 moles/min.