CN103258930B - A kind of GaN LED structure and preparation method - Google Patents

Abstract

The present invention relates to a kind of LED ray structure, especially a kind of GaN? LED structure and preparation method.A kind of GaN? LED structure and preparation method, comprise GaN? LED structure sheaf, and adopt pGaN hexagonal micron post layer (106) as the surface of p-type electric-conducting layer.Compared with the LED of traditional flat surfaces, the LED employing pGaN hexagonal micron bar technology is more efficient, and the light loss caused by total internal reflection is minimum.Simultaneously with the LED stable performance of pGaN hexagonal micron bar technology, electric property and ageing properties almost as broad as long with traditional plane surface LED.In addition, do not improve on cost of manufacture with the LED of pGaN hexagonal micron bar technology and traditional plane surface LED yet.The present invention is simply compact, and technique is simple, corrosion-resistant, improves the luminous efficiency of LED component.

Description

A kind of GaN LED structure and preparation method

Technical field

The present invention relates to a kind of epitaxial slice structure and preparation method thereof, especially a kind of GaN LED epitaxial wafer structure and preparation method.

Background technology

Group iii nitride semiconductor has the band structure of wurtzite structure and direct band gap, is applicable to doing light-emitting diode.Aluminium nitride (AlN), gallium nitride (GaN), indium nitride (InN) band-gap energy are 6.2ev respectively, 3.4ev, 0.7ev, therefore, under room temperature AlGaInN band-gap energy can from 6.2ev to 0.7ev between modulate, depend on the molar constituent that Al, Ga, In respectively account for.The light-emitting diode of AlGaInN material making from redness to ultraviolet light can be used in theory.Since the nineties in last century, the infrared light-emitting diode having caused great interest, particularly high brightness in academia and industrial circle to ultraviolet light photo device that group III nitride material makes brings very high commercial value.

Because there is the difference of refractive index between GaN (n=2.5) and air (n=1.0), total reflection is there occurs, even if the critical angle of the light of active area of can escaping out in traditional plane surface visible LED is about 23% at semiconductor and Air Interface place.Particularly for ultraviolet LED, there is absorption to ultraviolet light in GaN material itself or substrate (as Si or SiC), so the external quantum efficiency of ultraviolet LED will far below visible LED.In order to solve the low problem of external quantum efficiency, Duo Zu research team has proposed several method to improve exterior light extraction efficiency, the microcosmic alligatoring of device surface: chemical corrosion, the chemical etching of nanoscale is (with reference to people such as M.S.Minsky 1996 at Appl.Phys.Lett.Volume68, the Room-temperaturephotoenhancedwetetchingofGaN that 1531 – 1533 deliver), surface electrochemistry process is (with reference to K.Kim, J. wait people 2007 at Appl.Phys.Lett.Volume90, 181912, the AnodicnanoclustersofGaN delivered), using inorganic or organic mask to be ICP selectively etches (with reference to the people such as W.Y.Fu 2009 at Appl.Phys.Lett.Volume95, 133125, the Close-packedhemiellipsoidarrays:Aphotonicbandgapstructur epatternedbynanospherelithography delivered), self-organized colloidal particle, microphase-separated etc., also have growth in graphical sapphire substrate to improve exterior light to extract.There is shortcoming: etch process environment is unfriendly, manufacturing cost is high (with reference to the people such as ManshikPark 2011 at J.CrystalGrowthvolume326, 28 – 32, the StudyonphotoluminescenceofGaN-basedUV-LEDswithrefractive indexgradientpolymericnanopatterns delivered), the unaccommodated wavelength of deposition surface roughening of some kind is less than the ultraviolet LED of 385nm (with reference to people such as S.C.Huang 2009 at J.CrystalGrowthvolume311, 867 – 870, the Improvedoutputpowerof400-nmInGaN/AlGaNLEDsusinganovelsur facerougheningtechnique delivered), although surface roughness increases, it is not very high that exterior light is extracted yet, near ultraviolet LED is difficult to more than more than 35%.

Summary of the invention

For solving the problem, a kind of LED structure with pGaN hexagonal micron bar technology of the present invention and preparation method, it is simple and compact for structure.The critical angle that can overcome in traditional plane surface LED the light of active area of can escaping out is less, the shortcoming that external quantum efficiency is lower.By reducing the light loss that inner full-reflection causes, improve external quantum efficiency, and then improve brightness.

For achieving the above object, the invention provides a kind of GaN LED epitaxial wafer structure with pGaN hexagonal micron post, comprise GaN LED epitaxial wafer structure layer, and adopt pGaN hexagonal micron post layer (106) as the surface of p-type electric-conducting layer.

Described GaN LED epitaxial wafer structure layer comprises the undoped GaN layer (103) be grown on resilient coating (102), the upper growth of undoped GaN layer (103) has n type gallium nitride layer (104), the upper growth of n type gallium nitride layer (104) has multiple quantum well layer (11), the upper growth of multiple quantum well layer (11) has P type aln layer (105), and the upper growth of P type aln layer (105) has P type hexagonal micron post layer (106).

Described pGaN hexagonal micron post (106) growth is on p-type AlGaN layer (105) surface of high Al contents, and the diameter of hexagonal micron post is 1 ~ 6 μm, height 50 ~ 500nm.

In the multiple quantum well layer (11) of described GaN LED epitaxial wafer structure layer, the molar concentration scope of In is 0.001 ~ 0.3.

Described p-type AlGaN layer (105) thickness is the molar concentration of 10 ~ 100nm, Al is 0.2 ~ 0.35.

The thickness of described resilient coating (102) is 10nm ~ 100nm; Resilient coating (102) is GaN layer, AlN resilient coating, AlxGa1-xN layer, InxGa1-xN layer or AlxInyGa1-x-yN layer; Wherein, x is 0.01 ~ 0.99, y is 0.01 ~ 0.99.

A kind of GaN LED epitaxial wafer structure preparation method with pGaN hexagonal micron post comprises the steps:

(a), provide substrate (101), and by described substrate (101) high temperature purification 5 ~ 10 minutes under the H2 atmosphere of 1050 DEG C ~ 1250 DEG C;

(b), under H2 atmosphere, the substrate (101) after above-mentioned high temperature purification is cooled to 500 DEG C ~ 600 DEG C, and utilize MOCVD technique at the upper grown buffer layer (102) of substrate (101);

(c), on above-mentioned resilient coating (102) by MOCVD technique growing GaN LED structure sheaf.

The described GaN LED epitaxial wafer structure preparation method with pGaN hexagonal micron post, comprises the steps:

Described GaN LED epitaxial wafer structure layer growth process is as follows:

(c1) substrate of resilient coating (102) (101) ambient temperature, by growth is had to rise to 1000 DEG C ~ 1200 DEG C, and at resilient coating (102) upper growth undoped GaN layer (103);

(c2), at above-mentioned substrate (101) upper growth n type gallium nitride layer (104), described n type gallium nitride layer (104) is covered in undoped GaN layer (103);

(c3), under above-mentioned substrate (101) is positioned over N2 atmosphere, temperature is made to be 740 DEG C ~ 860 DEG C, with the quantum well layer at upper growth 5 ~ 15 periodic structures of n type gallium nitride layer (104), to form multiple quantum well layer (11);

(c4) temperature is made to be 750 DEG C ~ 1000 DEG C, at the upper growing P-type aln layer (105) of multiple quantum well layer (11) under, above-mentioned substrate (101) being positioned over H2 atmosphere again;

(c5), at upper growing P-type hexagonal micron post layer (106) of aforementioned p-type aln layer (105).

Use successful of the present invention, the LED of AlGaN employs the light output of pGaN hexagonal micron bar technological improvement.Compared with the LED of traditional flat surfaces, the LED employing pGaN hexagonal micron bar technology is more efficient, and the light loss caused by total internal reflection is minimum.Under the driving of 350mA electric current, use near the LED(peak wavelength 370nm of pGaN hexagonal micron bar technology) than near the LED(peak wavelength 370nm of traditional plane surface) optical output power high by 88%.Simultaneously with the LED stable performance of pGaN hexagonal micron bar technology, electric property and ageing properties almost as broad as long with traditional plane surface LED.In addition, do not improve on cost of manufacture with the LED of pGaN hexagonal micron bar technology and traditional plane surface LED yet.GaNLED processing step with pGaN hexagonal micron post layer is simple and convenient, can greatly improve GaNLED light extraction efficiency, simultaneously simple and compact for structure, and technique is simple, corrosion-resistant, improves the luminous efficiency of LED component.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention.

11-multiple quantum well layer, 101-substrate, 102-resilient coating, 103-undoped GaN layer, 104-N type gallium nitride layer, 105-P type aln layer, 106-P type hexagonal micron post layer in figure.

Embodiment

Below in conjunction with concrete drawings and Examples, the invention will be further described.

embodiment 1

As shown in Figure 1: in order to LED structure can be made can to have good light extraction efficiency, improve the optical output power of LED, the present invention includes GaN LED epitaxial wafer structure layer and P type hexagonal micron post layer 106.Wherein, P type hexagonal micron post layer 106 is positioned at the top of GaN LED epitaxial wafer structure layer, grows after the growth having terminated p-type AlGaN layer 105.And all GaN LED epitaxial wafer structure is grown on substrate 101 layers, in order to can make on substrate 101 can growing GaN LED structure sheaf, on substrate 101, growth has resilient coating 102, and described GaN LED epitaxial wafer structure layer growth is on resilient coating 102.

The thickness of described substrate 101 is 50mm ~ 300mm, the crystalline phase of substrate 101 is the single crystalline layer of <001>, <111>, <110>, can select sapphire, Si, SiC and GaN.

The thickness of described resilient coating 102 is 10nm ~ 100nm; Resilient coating 102 is GaN layer, AlN resilient coating, AlxGa1-xN layer, InxGa1-xN layer or AlxInyGa1-x-yN layer; Wherein, x is 0.01 ~ 0.99, y is 0.01 ~ 0.99.

Described GaN LED epitaxial wafer structure layer comprises growth in the undoped GaN layer 103 be grown on resilient coating 102, described undoped GaN layer 103 n type gallium nitride layer 104, on described n type gallium nitride layer 104, growth has multiple quantum well layer 11, on described multiple quantum well layer 11, growth has P type aln layer 105 (P type AlxGa1-XN, x scope is 0.2 ~ 0.35), on described P type aln layer 105, growth has P type hexagonal micron post layer 106.The thickness of described undoped GaN layer 103 is 500 ~ 2000nm.

embodiment 2

As shown in Figure 1: the above-mentioned GaN epitaxy chip architecture based on substrate 101 can be prepared by following technique, whole technical process adopts metal-organic chemical vapor deposition equipment method (MOCVD, MetalorganicChemicalVaporDeposition) growth technique, substrate 101 selects the sapphire PSS substrate 101 of <001> crystalline phase, metal organic source and nitrogenous source are trimethyl gallium (TMGa) respectively, trimethyl indium (TMIn), triethyl-gallium (TEGa), trimethyl aluminium (TMAl) and ammonia (NH3), n-type dopant is the silane (SiH4) that the H2 of 200ppm carries, p-type dopant is two luxuriant magnesium (Cp2Mg), the process conditions of described MOCVD are known by the art personnel, are specially:

A, provide substrate 101, and by described substrate 101 high temperature purification 5 ~ 10 minutes under the H2 atmosphere of 1050 DEG C ~ 1250 DEG C;

B, under H2 atmosphere, the substrate 101 after above-mentioned high temperature purification is cooled to 500 DEG C ~ 600 DEG C, and utilizes MOCVD technique resilient coating 102 on the substrate 101;

C, on above-mentioned resilient coating 102 by MOCVD technique growing GaN LED structure layer.

It is consistent that preparation process and existing employing Sapphire Substrate 101 due to GaNLED structure sheaf grow the Step By Condition obtaining GaNLED structure sheaf, the embodiment of the present invention introduces corresponding step by following step, and the detailed preparation process of whole GaNLED structure sheaf is known by the art personnel; Comprise particularly:

C1, under H2 atmosphere, there is substrate 101 ambient temperature of resilient coating 102 to rise to 1000 DEG C ~ 1200 DEG C growth, and grow undoped GaN layer 103 on resilient coating 102;

C2, on above-mentioned substrate 101, grow n type gallium nitride layer 104, described n type gallium nitride layer 104 is covered in undoped GaN layer 103;

C3, under above-mentioned substrate 101 is positioned over N2 atmosphere, temperature is made to be 740 DEG C ~ 860 DEG C, to grow the quantum well layer of 5 ~ 15 periodic structures on n type gallium nitride layer 104, to form multiple quantum well layer 11;

C4, above-mentioned ceramic substrate 101 is positioned over H2 atmosphere again under and make temperature be 750 DEG C ~ 1000 DEG C, growing P-type aln layer 105 (P type AlxGa1-XN, x scope is 0.2 ~ 0.35) on multiple quantum well layer 11;

C5, at the upper growing P-type gallium nitride hexagonal micron post layer 106 of aforementioned p-type aln layer 105 (P type AlxGa1-XN, x scope is 0.2 ~ 0.35).

After obtaining GaN LED epitaxial wafer structure layer by step c, if when needing to prepare corresponding LED, only need on GaN LED epitaxial wafer structure layer, to prepare P electrode and N electrode by conventional LED electrical pole preparation technology.

embodiment 3

The GaN epitaxy chip architecture preparation process that the present invention is based on substrate 101 is described below by several specific embodiment.

The present invention adopts MOCVD technique to prepare, step 1, the PSS Sapphire Substrate 101 of <001> crystalline phase is put into reative cell, then in H2 environment, be warming up to 1050 DEG C, stablize 10 minutes, high temperature purification is carried out to substrate 101; The low temperature GaN base layer of step 2, growth 20nm thickness, using as the resilient coating 102 being grown on substrate 101; Step 3, on resilient coating 102, grow the undoped GaN layer 103 of 1mm thickness; The n type gallium nitride layer 104 of step 4, growth 1.5mm thickness; Step 5, in N2 environment growth obtain the multiple quantum well layer 11 in 12 cycles, in described multiple quantum well layer 11, GaN barrier layer thickness is 20nmIn, GaN well layer thickness is 1.6nm; The P type Al0.3Ga0.75N layer of step 6, growth 40nm thickness, obtains P type aln layer 105; The P type hexagonal micron post layer 106 of step 7, growth 150nm thickness; Step 8, be cooled to room temperature, growth terminates.

embodiment 4

Adopt the preparation of MOCVD technique, step 1, the plain film Sapphire Substrate 101 of <001> crystalline phase is put into reative cell, then in H2 environment, be warming up to 1050 DEG C, stablize 10 minutes, high temperature purification is carried out to substrate 101; The low temperature AI 0.2Ga0.8N basic unit of step 2, growth 20nm thickness, to form resilient coating 102; The undoped GaN layer 103 of step 3, growth 1mm thickness; The n type gallium nitride layer 104 of step 4, growth 1.5mm thickness; Step 5, in N2 environment growth obtain the quantum well layer in 8 cycles, obtain multiple quantum well layer 11, in described multiple quantum well layer 11, GaN barrier layer thickness is 20nm, InGaN well layer thickness is 1.6nm; The p-Al0.2Ga0.85N layer of step 6, growth 30nm thickness, obtains P type aln layer 105; The P type hexagonal micron post layer 106 of step 7, growth 150nm thickness; Step 8, be cooled to room temperature, growth terminates.

embodiment 5

Adopt the preparation of MOCVD technique, step 1, the plain film SiC substrate 101 of <001> crystalline phase is put into reative cell, then in H2 environment, be warming up to 1050 DEG C, stablize 10 minutes, high temperature purification is carried out to substrate 101; The low temperature AI N basic unit of step 2, growth 20nm thickness, to form resilient coating 102; The undoped GaN layer 103 of step 3, growth 1mm thickness; The n type gallium nitride layer 104 of step 4, growth 1.5mm thickness; Step 5, in N2 environment growth obtain the quantum well layer in 10 cycles, obtain multiple quantum well layer 11, in described multiple quantum well layer 11, GaN barrier layer thickness is 20nm, InGaN well layer thickness is 1.6nm; The p-Al0.25Ga0.85N layer of step 6, growth 50nm thickness, obtains P type aln layer 105; The P type hexagonal micron post layer 106 of step 7, growth 150nm thickness; Step 8, be cooled to room temperature, growth terminates.

embodiment 6

Adopt the preparation of MOCVD technique, step 1, the plain film GaN substrate 101 of <001> crystalline phase is put into reative cell, then in H2 environment, be warming up to 1050 DEG C, stablize 10 minutes, high temperature purification is carried out to substrate 101; The undoped GaN layer 103 of step 2, growth 1mm thickness; The n type gallium nitride layer 104 of step 3, growth 1.5mm thickness; Step 4, in N2 environment growth obtain the quantum well layer in 15 cycles, obtain multiple quantum well layer 11, in described multiple quantum well layer 11, GaN barrier layer thickness is 20nm, InGaN well layer thickness is 1.6nm; The p-Al0.25Ga0.85N layer of step 5, growth 20nm thickness, obtains P type aln layer 105; The P type hexagonal micron post layer 106 of step 6, growth 150nm thickness; Step 7, be cooled to room temperature, growth terminates.

Invention first prepare GaN LED epitaxial wafer structure layer by MOCVD common process, after pAlGaN electronic blocking layer growth is complete, utilize the interface of pAlGaN and the GaN of high Al concentration existence hexagon and hexagonal pyramid minute surface ( ), ( ) etc. defect continued growth p-GaN grow hexagonal micron post.GaNLED processing step with pGaN hexagonal micron post layer is simple and convenient, can greatly improve GaNLED light extraction efficiency, simultaneously simple and compact for structure, and technique is simple, corrosion-resistant, improves the luminous efficiency of LED component.

Claims (1)

1. with a GaN LED epitaxial wafer structure for pGaN hexagonal micron post, it is characterized in that: comprise GaN LED epitaxial wafer structure layer, and adopt pGaN hexagonal micron post layer (106) as the surface of p-type electric-conducting layer;

Described GaN LED epitaxial wafer structure layer comprises the undoped GaN layer (103) be grown on resilient coating (102), the upper growth of undoped GaN layer (103) has n type gallium nitride layer (104), the upper growth of n type gallium nitride layer (104) has multiple quantum well layer (11), the upper growth of multiple quantum well layer (11) has P type AlGaN layer (105), and the upper growth of P type AlGaN layer (105) has pGaN hexagonal micron post layer (106);

Described pGaN hexagonal micron post layer (106) growth is on p-type AlGaN layer (105) surface of high Al contents, and the diameter of hexagonal micron post is 1 ~ 6 μm, height 50 ~ 500nm;

P-type AlGaN layer (105) thickness is the molar concentration of 10 ~ 100nm, Al is 0.2 ~ 0.35;

In the multiple quantum well layer (11) of described GaN LED epitaxial wafer structure layer, the molar concentration scope of In is 0.001 ~ 0.3;

The thickness of described resilient coating (102) is 10nm ~ 100nm; Resilient coating (102) is GaN layer, AlN resilient coating, AlxGa1-xN layer, InxGa1-xN layer or AlxInyGa1-x-yN layer; Wherein, x is 0.01 ~ 0.99, y is 0.01 ~ 0.99.