CN106876545B - A kind of epitaxy method improving GaN base LED internal quantum efficiency - Google Patents

A kind of epitaxy method improving GaN base LED internal quantum efficiency Download PDF

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CN106876545B
CN106876545B CN201710140746.6A CN201710140746A CN106876545B CN 106876545 B CN106876545 B CN 106876545B CN 201710140746 A CN201710140746 A CN 201710140746A CN 106876545 B CN106876545 B CN 106876545B
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layer
gan
cap rock
low temperature
gas
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CN106876545A (en
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许并社
朱亚丹
卢太平
周小润
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Taiyuan University Of Technology Architectural Design And Research Institute Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
    • H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction

Abstract

The invention belongs to field of optoelectronic devices, and in particular to a kind of epitaxy method for improving GaN base LED internal quantum efficiency, the material structure include stacking gradually growing low temperature nucleating layer, unintentional doped gan layer, n-type GaN layer, InGaN/H on substrate2Multiple quantum well layer, electronic barrier layer, p-type GaN layer and the P type contact layer of the low temperature GaN/ high temperature GaN composition of gas treatment.Wherein H2The low temperature GaN cap rock of gas treatment is the H that small flow is passed through during growing cap rock2Gas.The present invention is used when growing the low temperature GaN cap rock of multicycle Quantum Well, is passed through the H of small flow in situ2Gas, improves crystal quality, additionally it is possible to reduce the cluster of In, improve the uniformity of In component, advantageously form precipitous trap and build interface at the defects of can not only removing or be passivated the dislocation of light emitting region, impurity, V-arrangement hole.Therefore, the internal quantum efficiency of GaN base LED can be improved through the invention.

Description

A kind of epitaxy method improving GaN base LED internal quantum efficiency
Technical field
The invention belongs to field of optoelectronic devices, and in particular to a kind of extension side for improving GaN base LED internal quantum efficiency Method.
Background technique
Gallium nitride based light emitting diode (Light Emitting Diode, LED) have high brightness, low energy consumption, the long-life, The features such as fast response time and environmental protection, is widely used in indoor and street lighting, traffic signals and outdoor display, Automobile The multiple fields such as lamp illumination, liquid crystal backlight.Therefore, large power white light LED is considered as the lighting source of 21 century.
Current commercialized GaN base LED epitaxial structure is mostly different along [0001] direction (c-axis) on a sapphire substrate Matter extension.Due to Sapphire Substrate and wurtzite structure GaN on lattice constant, thermal expansion coefficient there are biggish difference, make Obtain the defect density in GaN body material up to 108cm-2.Due to the hereditary effect of defect in epitaxial growth, can defect be prolonged Extend to multiple quantum wells region.Secondly, in order to improve the incorporation efficiency of In, the growth temperature of InGaN well layer not above 800 DEG C, And the growth temperature of the ingredient of In more high request is lower, however NH at low temperature3Crack insufficient, therefore the meeting in epitaxial growth Many defects are formed, such as the vacancy N, antistructure defect etc., so that crystal quality declines, LED luminous efficiency is seriously reduced.In order to improve Crystal quality, the growth temperature of GaN barrier layer are generally higher than the growth temperature of InGaN well layer, this just needs to introduce low temperature GaN lid Layer is come the loss of In when preventing heating.It is brilliant since growth temperature is low although GaN cap rock can effectively prevent the loss of In Weight is poor.It is located at the defect of multi-quantum well active region, such as In cluster, misfit dislocation, threading dislocation, stacked layers in a word Mistake, surface crater and V-arrangement hole etc., will form non-radiative recombination center, so that carrier is largely reduced due to non-radiative recombination, Seriously reduce the internal quantum efficiency of LED.
Summary of the invention
Present invention aims in view of the above-mentioned problems, provide it is a kind of improve GaN base LED internal quantum efficiency epitaxy method, This method can not only reduce quantum well region defect concentration, and preparation method is simple, and preparation cost is lower.
The present invention is achieved by the following technical solutions: a kind of epitaxy method improving GaN base LED internal quantum efficiency, The following steps are included:
One substrate is provided and surface cleaning is carried out to substrate；
GaN nucleating layer and the high temperature anneal are grown on substrate after the cleaning；
Unintentional doped gan layer is grown on GaN nucleating layer after annealing；
The growing n-type GaN layer in unintentional doped gan layer；
Grow multi-quantum well luminescence layer in n-type GaN layer, the multi-quantum well luminescence layer is several pairs of InGaN well layer/low Warm GaN cap rock/high temperature GaN barrier layer is successively alternately stacked composition from bottom to top, and is passed through H in low temperature GaN cap rock growth course2Gas Body；
P-AlGaN electronic barrier layer is grown in multi-quantum well luminescence layer；
P-GaN layer and p-GaN contact layer are grown on p-AlGaN electronic barrier layer.
When growing GaN nucleating layer and the high temperature anneal in the present invention, the temperature of the high temperature anneal is 950- 1110℃。
When concrete application, NH is first passed through in a growth cycle of the multi-quantum well luminescence layer3Gas, the source In, the source Ga, Grow InGaN well layer；After well layer has been grown, it is simply turned off the source In, and be passed through H2, grow GaN cap rock；After cap rock has been grown, Ga is closed Source and H2Gas simultaneously starts to warm up, and after temperature reaches barrier layer growth temperature and stablizes, then opens the source Ga, grows GaN barrier layer.To Barrier layer growth is completed, and is closed the source Ga and is started to cool down, after temperature reaches well layer growth temperature and stablizes, then opens the source Ga and In Source grows the well layer of next cycle.Certainly, it has constantly been passed through N always during growth forms GaN base LED2Gas, N2 On the one hand gas serves as carrier gas, on the one hand provide as compensation gas.
The growth temperature of low temperature GaN cap rock is consistent with the growth temperature of InGaN well layer in the present invention, high temperature GaN barrier layer Growth temperature is higher than the growth temperature of InGaN well layer and GaN cap rock.Low temperature GaN cap rock is used to protect the In in InGaN well layer former Son prevents In atom from evaporating and being desorbed in temperature-rise period.
In addition, the present invention during growing multiple quantum wells, is only passed through H in the growth course of low temperature GaN cap rock2, and There is no H in the growth course of InGaN well layer and GaN barrier layer2Gas.
It is further preferred that the H2The flow of gas is total for all gas being passed through in low temperature GaN cap rock growth course The 0.1%-20% of flow.The all gas only contains NH3Gas, H2Gas and N2Gas.
When it is implemented, InGaN well layer/low temperature GaN cap rock/high temperature GaN barrier layer week in the multi-quantum well luminescence layer Issue is 1-20 pairs.
Preferably, in the multi-quantum well luminescence layer InGaN well layer with a thickness of 1-6nm, low temperature GaN cap rock with a thickness of 0.2-6nm, GaN barrier layer with a thickness of 5-20nm.
Preferably, In component is 5-40% in mole percent in the InGaN well layer.
It is passed through H in situ when growing the low temperature GaN cap rock of multicycle Quantum Well by process above2Gas, can not only The defects of dislocation of enough removals or passivation light emitting region, impurity, V-arrangement hole, improve crystal quality, additionally it is possible to reduce the group of In Cluster improves the uniformity of In component, advantageously forms precipitous trap and builds interface.Therefore, it can achieve through the invention and improve GaN The purpose of the internal quantum efficiency of base LED.
Detailed description of the invention
Fig. 1 is the epitaxial wafer flow chart of conventional method growth.
Fig. 2 is the epitaxial wafer flow chart of prior art growth.
Fig. 3 is that the present invention uses InGaN well layer/H2The low temperature GaN cap rock of gas treatment/high temperature GaN barrier layer composition is more The epitaxial wafer and tradition InGaN well layer/low temperature GaN cap rock/high temperature GaN barrier layer structure room temperature (300K) light of quantum well structure are glimmering Spectrum comparison diagram.Certainly, when doing room temperature photoluminescence spectrum, the unique variable when present invention and traditional multi-quantum pit structure compare For whether by H2Gas treatment, other conditions and structure are identical.In addition H is passed through in low temperature GaN cap rock growth course in Fig. 32 The flow of gas is the 2.5% of total flow.The present invention uses InGaN well layer/H as seen from the figure2The low temperature GaN of gas treatment The epitaxial wafer emission wavelength blue shift of the multi-quantum pit structure of cap rock/high temperature GaN barrier layer composition 12nm, although wavelength blue shift, It is that luminous intensity at room temperature about improves 3 times.The contrast test of above-mentioned photoluminescence spectrum is using He-Cd laser, excitation The PL spectrometer of wavelength 325nm.
Fig. 4 is that the present invention uses InGaN well layer/H2The low temperature GaN cap rock of gas treatment/high temperature GaN barrier layer composition is more The epitaxial wafer and tradition InGaN well layer/low temperature GaN cap rock of quantum well structure/high temperature GaN barrier layer composition multi-quantum pit structure The internal quantum efficiency comparison diagram of epitaxial wafer.Certainly, when doing internal quantum efficiency measurement, the present invention and traditional multi-quantum pit structure Whether unique variable is by H when comparing2Gas treatment, other conditions and structure are identical.In addition low temperature of the present invention in Fig. 4 H is passed through in GaN cap rock growth course2The flow of gas is the 2.5% of total flow.Internal quantum efficiency value uses following calculation formula:.Wherein I10KAnd I300KThe integrated intensity of the photoluminescence spectrum respectively measured in 10K and 300K.It can be seen that this Invention uses InGaN well layer/H2The extension of the low temperature GaN cap rock of gas treatment/high temperature GaN barrier layer composition multi-quantum pit structure Piece internal quantum efficiency about improves 2.1 times.The test of photoluminescence spectrum is using He-Cd laser, excitation when 10K and 300K The PL spectrometer of wavelength 325nm.
Specific embodiment
Further description is carried out to the present invention below by embodiment.As mentioned in working as in specification in the whole text " only containing " or " only " is a closed term, therefore should be construed to " only "." about " refer in acceptable error range Interior, those skilled in the art can solve the technical problem within a certain error range, basically reach the technical effect.
The present invention provides a kind of epitaxy methods (referring to fig. 2) for improving GaN base LED internal quantum efficiency, including following step It is rapid:
One substrate is provided and surface cleaning is carried out to substrate；
GaN nucleating layer and the high temperature anneal are grown on substrate after the cleaning；
Unintentional doped gan layer is grown on GaN nucleating layer after annealing；
The growing n-type GaN layer in unintentional doped gan layer；
Grow multi-quantum well luminescence layer in n-type GaN layer, the multi-quantum well luminescence layer is several pairs of InGaN well layer/low Warm GaN cap rock/high temperature GaN barrier layer is successively alternately stacked composition from bottom to top, and is passed through H in low temperature GaN cap rock growth course2Gas Body；
P-AlGaN electronic barrier layer is grown in multi-quantum well luminescence layer；
P-GaN layer and p-GaN contact layer are grown on p-AlGaN electronic barrier layer.
One of specific embodiment of further epitaxy method of the present invention is: epitaxy method of the invention is It is realized in the instrument of MOCVD board model Aixtron TS300.When wherein growing multi-quantum well luminescence layer, keep anti- It answers cavity pressure 200-600mBar, be passed through flow as the NH of the adoptable range 2000-6000sccm of 4000sccm()3Gas The flow of body, the source In and the source Ga is by carrier gas N2It conveys into reaction chamber, wherein In source flux is 20-400sccm, Ga source flux For 5-100sccm.InGaN well layer is grown in the range of temperature is 650-800 DEG C, pressure in growth course, temperature and logical Enter NH3Gas, the source In, the source Ga flow constant；After well layer has been grown, it is simply turned off the source In, and is passed through and accounts for total flow 2.5% H2(the arbitrary volume percentage in 0.1%-20%, such as 0.1%, 10% or 20%) may be selected, grow GaN cap rock, growth course Middle pressure, temperature and it is passed through NH3Gas, the source Ga flow constant；After cap rock has been grown, the source Ga and H are closed2Gas is simultaneously opened Beginning is warming up to 750-950 DEG C, keeps the pressure of reaction chamber constant, and ammonia flow is constant, and Ga source flux is 10-100sccm, temperature Start to grow GaN barrier layer after stabilization, pressure, temperature and is passed through NH in growth course3The flow holding of gas, the source In, the source Ga It is constant.It grows and completes to barrier layer, close the source Ga and the source In starts to cool down, after temperature reaches well layer growth temperature and stablizes, then It is passed through the source Ga that the source In, flow that flow is 20-400sccm are 5-100sccm, grows the well layer of next cycle, in repetition State step.Periodicity is 1-20 pairs.Wherein N2Maintain the total flow of reaction chamber in entire Quantum Well as carrier gas and compensation gas It is held essentially constant in growth course, N2Flow in 2000-6000sccm, during the growth process can be according to NH3, the source In, Ga Source, H2Changes in flow rate compensated accordingly.
Further, in the multi-quantum well luminescence layer InGaN well layer with a thickness of 1-6nm, low temperature GaN cap rock with a thickness of 0.2-6nm, GaN barrier layer with a thickness of 5-20nm.
Further, In component is 5-40% in mole percent in the InGaN well layer.

Claims (4)

1. a kind of epitaxy method for improving GaN base LED internal quantum efficiency, which comprises the following steps:
One substrate is provided and surface cleaning is carried out to substrate；
GaN nucleating layer and the high temperature anneal are grown on substrate after the cleaning；
Unintentional doped gan layer is grown on GaN nucleating layer after annealing；
The growing n-type GaN layer in unintentional doped gan layer；
Multi-quantum well luminescence layer is grown in n-type GaN layer, the multi-quantum well luminescence layer is several pairs of InGaN well layer/low temperature GaN cap rock/high temperature GaN barrier layer is successively alternately stacked composition, the growth temperature and InGaN well layer of low temperature GaN cap rock from bottom to top Growth temperature it is consistent, the growth temperature of high temperature GaN barrier layer is higher than the growth temperature of InGaN well layer and low temperature GaN cap rock, and low H is passed through in warm GaN cap rock growth course2Gas；The H2The flow of gas is the institute that is passed through in low temperature GaN cap rock growth course There is the 2.5% of total gas flow rate；
P-AlGaN electronic barrier layer is grown in multi-quantum well luminescence layer；
P-GaN layer and p-GaN contact layer are grown on p-AlGaN electronic barrier layer.
2. a kind of epitaxy method for improving GaN base LED internal quantum efficiency according to claim 1, which is characterized in that described InGaN well layer/low temperature GaN cap rock/high temperature GaN barrier layer periodicity is 1-20 pairs in multi-quantum well luminescence layer.
3. a kind of epitaxy method for improving GaN base LED internal quantum efficiency according to claim 2, which is characterized in that described In multi-quantum well luminescence layer InGaN well layer with a thickness of 1-6nm, low temperature GaN cap rock with a thickness of 0.2-6nm, the thickness of GaN barrier layer Degree is 5-20nm.
4. a kind of epitaxy method for improving GaN base LED internal quantum efficiency according to claim 3, which is characterized in that described In component is 5-40% in mole percent in InGaN well layer.
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