CN103258930A - GaN LED epitaxial wafer structure and preparation method - Google Patents

Abstract

The invention relates to an LED lighting structure, in particular to a GaN LED epitaxial wafer structure and a preparation method. The GaN LED expitaxial wafer structure comprises a GaN LED expitaxial wafer structure layer and a pGaN hexagonal micron pillar layer (106) serving as the surface of a p-type conducting layer. Compared with a traditional LED with the flat surface, an LED adopting the pGaN hexagonal micron bar technology is much efficient and minimum in light loss caused by total internal reflection. Meanwhile, the LED adopting the pGaN hexagonal micron bar technology is stable in performance, and the electrical property and the aging property of the LED adopting the pGaN hexagonal micron bar technology are hardly different from those of the traditional LED with the flat surface. In addition, the manufacturing cost of the LED adopting the pGaN hexagonal micron bar technology is not increased compared with that of the traditional LED with the flat surface. The GaN LED expitaxial wafer structure is simple, compact, simple in technological process and corrosion-resisting, and the luminous efficiency of an LED device is improved.

Description

A kind of GaN LED epitaxial slice 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 slice structure and preparation method.

Background technology

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

Because there is the difference of refractive index between GaN (n=2.5) and the air (n=1.0), at semiconductor and air interface place total reflection has taken place, even the critical angle of the light of the active area of can escaping out among traditional plane surface visible light LED is about 23%.Particularly for ultraviolet LED, there are absorption in GaN material itself or substrate (as Si or SiC) to ultraviolet light, and so the external quantum efficiency of ultraviolet LED will be far below visible light LED.In order to solve the low problem of external quantum efficiency, how group research team has proposed several method is improved the 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. Volume 68, the Room-temperature photoenhanced wet etching of GaN that 1531 – 1533 deliver), surface electrochemistry is handled (with reference to K. Kim, J. wait people 2007 at Appl. Phys. Lett. Volume 90,181912, the Anodic nanoclusters of GaN that delivers), use inorganic or organic mask to do selectively etching of ICP (with reference to people such as W.Y.Fu 2009 at Appl. Phys. Lett. Volume 95,133125, the Close-packed hemiellipsoid arrays:A photonic band gap structure patterned by nanosphere lithography that delivers), the self-organized colloidal particle, microphase-separated etc. also have in the growth of graphic sapphire substrate and improve the exterior light extraction.Have shortcoming: the etch process environment is unfriendly, the manufacturing cost height is (with reference to people such as Manshik Park 2011 at J. Crystal Growth volume 326,28 – 32, the Study on photoluminescence of GaN-based UV-LEDs with refractive index gradient polymeric nanopatterns that delivers), the unaccommodated wavelength of deposition surface roughening of some kind less than the ultraviolet LED of 385nm (with reference to people such as S.C. Huang 2009 at J. Crystal Growth volume 311,867 – 870, the Improved output power of 400-nm InGaN/AlGaN LEDs using a novel surface roughening technique that delivers), though surface roughness increases, it is not very high that exterior light is extracted yet, and near ultraviolet LED is difficult to surpass more than 35%.

Summary of the invention

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

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

Described GaN LED epitaxial slice structure layer comprises the non-Doped GaN layer (103) that grows on the resilient coating (102), non-Doped GaN layer (103) is gone up growth n type gallium nitride layer (104), n type gallium nitride layer (104) is gone up growth multiple quantum well layer (11), multiple quantum well layer (11) is gone up growth P type aln layer (105), and P type aln layer (105) is gone up growth P type hexagonal micron post layer (106).

Described pGaN hexagonal micron post (106) is grown in p-type AlGaN layer (105) surface of high Al component, and the diameter of hexagonal micron post is 1 ~ 6 μ m, height 50 ~ 500nm.

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

Described p-type AlGaN layer (105) thickness is 10 ~ 100nm, and the molar concentration of 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 that 0.01 ~ 0.99, y is 0.01 ~ 0.99.

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

(a), provide substrate (101), and with described substrate (101) high temperature purification 5 ~ 10 minutes under 1050 ℃ ~ 1250 ℃ H2 atmosphere;

(b), under the H2 atmosphere substrate behind the above-mentioned high temperature purification (101) is being cooled to 500 ℃ ~ 600 ℃, and utilize MOCVD technology to go up grown buffer layer (102) at substrate (101);

(c), pass through MOCVD technology growing GaN LED epitaxial slice structure layer at above-mentioned resilient coating (102).

The described GaN LED epitaxial slice structure preparation method who has pGaN hexagonal micron post comprises the steps:

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

(c1), have substrate (101) ambient temperature of resilient coating (102) to rise to 1000 ℃ ~ 1200 ℃ growth, and at resilient coating (102) growth non-Doped GaN layer (103);

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

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

(c4), to be positioned over above-mentioned substrate (101) under the H2 atmosphere again and to make temperature be 750 ℃ ~ 1000 ℃, goes up growing P-type aln layer (105) at multiple quantum well layer (11);

(c5), go up growing P-type hexagonal micron post layer (106) at above-mentioned P type aln layer (105).

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

Description of drawings

Fig. 1 is structural representation of the present invention.

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

Embodiment

The invention will be further described below in conjunction with concrete drawings and Examples.

Embodiment 1

As shown in Figure 1: in order to make the LED structure can have light extraction efficiency preferably, improve the optical output power of LED, the present invention includes GaN LED epitaxial slice 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 slice structure layer, growth after the growth that has finished p-type AlGaN layer 105.And all GaN LED epitaxial slice structures grow on 101 layers of the substrates, can growing GaN LED epitaxial slice structure layer in order to make on the substrate 101, and growth has resilient coating 102 on the substrate 101, and described GaN LED epitaxial slice structure layer growth is on resilient coating 102.

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

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 that 0.01 ~ 0.99, y is 0.01 ~ 0.99.

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

Embodiment 2

As shown in Figure 1: above-mentioned GaN epitaxial slice structure based on substrate 101 can be by following technology preparation, whole technical process adopts metal-organic chemical vapor deposition equipment method (MOCVD, Metalorganic Chemical Vapor Deposition) growth technique, substrate 101 selects for use＜001〉crystalline phase sapphire PSS substrate 101, metal organic source and nitrogenous source are respectively trimethyl gallium (TMGa), 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, and the p-type dopant is two luxuriant magnesium (Cp2Mg); The process conditions of described MOCVD are the art personnel to be known, and is specially:

A, provide substrate 101, and with described substrate 101 high temperature purification 5 ~ 10 minutes under 1050 ℃ ~ 1250 ℃ H2 atmosphere;

B, under the H2 atmosphere substrate 101 behind the above-mentioned high temperature purification is cooled to 500 ℃ ~ 600 ℃, and is utilizing MOCVD technology resilient coating 102 on substrate 101;

C, at above-mentioned resilient coating 102 by MOCVD technology growing GaN LED structure sheaf.

Because the preparation process of GaN LED structure sheaf is consistent with the existing Step By Condition that adopts Sapphire Substrate 101 growths to obtain GaN LED structure sheaf, the embodiment of the invention is introduced corresponding step by following step, and the detailed preparation process of whole GaN LED structure sheaf is known by the art personnel; Comprise particularly:

C1, under the H2 atmosphere, have substrate 101 ambient temperatures of resilient coating 102 to rise to 1000 ℃ ~ 1200 ℃ growth, and at the non-Doped GaN layer 103 of resilient coating 102 growth;

C2, at above-mentioned substrate 101 growth n type gallium nitride layers 104, described n type gallium nitride layer 104 is covered in non-Doped GaN layer 103;

C3, to be positioned under the N2 atmosphere and to make temperature at above-mentioned substrate 101 be 740 ℃ ~ 860 ℃, with the quantum well layer of 5 ~ 15 periodic structures of growing at n type gallium nitride layer 104, to form multiple quantum well layer 11;

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

C5, go up growing P-type gallium nitride hexagonal micron post layer 106 at above-mentioned P type aln layer 105 (P type AlxGa1-XN, the x scope is 0.2 ~ 0.35).

When obtain GaN LED epitaxial slice structure layer by step c after, when preparing corresponding LED if desired, only need prepare the P electrode and the N electrode gets final product at GaN LED epitaxial slice structure layer by conventional LED technology for preparing electrode.

Embodiment 3

The present invention is based on the GaN epitaxial slice structure preparation process of substrate 101 below by several specific embodiment explanations.

The present invention adopts the preparation of MOCVD technology, and step 1, general's＜001〉crystalline phase PSS Sapphire Substrate 101 is put into reative cell, is warming up to 1050 ℃ then in the H2 environment, stablizes 10 minutes, and substrate 101 is carried out high temperature purification; The low temperature GaN basic unit of step 2, growth 20nm thickness is with as the resilient coating 102 that grows in substrate 101; Step 3, at the non-Doped GaN layer 103 of resilient coating 102 growth 1mm thickness; The n type gallium nitride layer 104 of step 4, growth 1.5mm thickness; Step 5, growth obtains the multiple quantum well layer 11 in 12 cycles in the N2 environment, and the GaN barrier layer thicknesses are 20nmIn in the described multiple quantum well layer 11, and GaN trap 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 ending.

Embodiment 4

Adopt the preparation of MOCVD technology, step 1, general's＜001〉crystalline phase plain film Sapphire Substrate 101 is put into reative cell, is warming up to 1050 ℃ then in the H2 environment, stablizes 10 minutes, and substrate 101 is carried out high temperature purification; The low temperature AI 0.2Ga0.8N basic unit of step 2, growth 20nm thickness is to form resilient coating 102; The non-Doped 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, growth obtains the quantum well layer in 8 cycles in the N2 environment, obtains multiple quantum well layer 11, and the GaN barrier layer thicknesses are 20nm in the described multiple quantum well layer 11, and InGaN trap 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 ending.

Embodiment 5

Adopt the preparation of MOCVD technology, step 1, general's＜001〉crystalline phase plain film SiC substrate 101 is put into reative cell, is warming up to 1050 ℃ then in the H2 environment, stablizes 10 minutes, and substrate 101 is carried out high temperature purification; The low temperature AI N basic unit of step 2, growth 20nm thickness is to form resilient coating 102; The non-Doped 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, growth obtains the quantum well layer in 10 cycles in the N2 environment, obtains multiple quantum well layer 11, and the GaN barrier layer thicknesses are 20nm in the described multiple quantum well layer 11, and InGaN trap 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 ending.

Embodiment 6

Adopt the preparation of MOCVD technology, step 1, general's＜001〉crystalline phase plain film GaN substrate 101 is put into reative cell, is warming up to 1050 ℃ then in the H2 environment, stablizes 10 minutes, and substrate 101 is carried out high temperature purification; The non-Doped 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, growth obtains the quantum well layer in 15 cycles in the N2 environment, obtains multiple quantum well layer 11, and the GaN barrier layer thicknesses are 20nm in the described multiple quantum well layer 11, and InGaN trap 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 ending.

Invention at first prepares GaN LED epitaxial slice structure layer by the MOCVD common process, after the pAlGaN electronic barrier layer has been grown, the pAlGaN that utilizes in high Al concentration and the hexagon that exists at the interface of GaN and hexagonal pyramid minute surface (

), (

) etc. defective continued growth p-GaN growth hexagonal micron post.The GaN LED processing step that has pGaN hexagonal micron post layer is simple and convenient, can improve GaN LED light extraction efficiency greatly, and simultaneously simple and compact for structure, technology is simple, and is corrosion-resistant, improved the luminous efficiency of LED device.

Claims (8)

1. a GaN LED epitaxial slice structure that has pGaN hexagonal micron post is characterized in that: comprise GaN LED epitaxial slice structure layer and adopt pGaN hexagonal micron post layer (106) as the surface of p-type conductive layer.

2. the GaN LED epitaxial slice structure that has pGaN hexagonal micron post according to claim 1, it is characterized in that: described GaN LED epitaxial slice structure layer comprises the non-Doped GaN layer (103) that grows on the resilient coating (102), non-Doped GaN layer (103) is gone up growth n type gallium nitride layer (104), n type gallium nitride layer (104) is gone up growth multiple quantum well layer (11), multiple quantum well layer (11) is gone up growth P type aln layer (105), and P type aln layer (105) is gone up growth P type hexagonal micron post layer (106).

3. the GaN LED epitaxial slice structure that has pGaN hexagonal micron post according to claim 1 and 2, it is characterized in that: described pGaN hexagonal micron post (106) is grown in p-type AlGaN layer (105) surface of high Al component, the diameter of hexagonal micron post is 1 ~ 6 μ m, height 50 ~ 500nm.

4. the GaN LED epitaxial slice structure that has pGaN hexagonal micron post according to claim 1 and 2 is characterized in that: the molar concentration scope of In is 0.001 ~ 0.3 in the multiple quantum well layer (11) of described GaN LED epitaxial slice structure layer.

5. the GaN LED epitaxial slice structure that has pGaN hexagonal micron post according to claim 2, it is characterized in that: p-type AlGaN layer (105) thickness is 10 ~ 100nm, and the molar concentration of Al is 0.2 ~ 0.35.

6. the GaN LED epitaxial slice structure that has pGaN hexagonal micron post according to claim 2, it is characterized in that: 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 that 0.01 ~ 0.99, y is 0.01 ~ 0.99.

7. a GaN LED epitaxial slice structure preparation method who has pGaN hexagonal micron post comprises the steps, it is characterized in that:

(a), provide substrate (101), and with described substrate (101) high temperature purification 5 ~ 10 minutes under 1050 ℃ ~ 1250 ℃ H2 atmosphere;

(b), under the H2 atmosphere substrate behind the above-mentioned high temperature purification (101) is being cooled to 500 ℃ ~ 600 ℃, and utilize MOCVD technology to go up grown buffer layer (102) at substrate (101);

(c), pass through MOCVD technology growing GaN LED epitaxial slice structure layer at above-mentioned resilient coating (102).

8. the GaN LED epitaxial slice structure preparation method who has pGaN hexagonal micron post according to claim 7 comprises the steps:

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

(c1), have substrate (101) ambient temperature of resilient coating (102) to rise to 1000 ℃ ~ 1200 ℃ growth, and at resilient coating (102) growth non-Doped GaN layer (103);

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

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

(c4), to be positioned over above-mentioned substrate (101) under the H2 atmosphere again and to make temperature be 750 ℃ ~ 1000 ℃, goes up growing P-type aln layer (105) at multiple quantum well layer (11);

(c5), go up growing P-type hexagonal micron post layer (106) at above-mentioned P type aln layer (105).

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