(19)
(11)EP 3 107 128 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
18.04.2018 Bulletin 2018/16

(21)Application number: 15769396.1

(22)Date of filing:  23.03.2015
(51)International Patent Classification (IPC): 
H01L 33/02(2010.01)
H01L 33/16(2010.01)
H01L 33/00(2010.01)
C30B 25/18(2006.01)
H01L 33/32(2010.01)
H01L 21/02(2006.01)
H01L 33/12(2010.01)
C30B 29/40(2006.01)
(86)International application number:
PCT/CN2015/074828
(87)International publication number:
WO 2015/144023 (01.10.2015 Gazette  2015/39)

(54)

PREPARATION METHOD OF A NON-POLAR BLUE LED EPITAXIAL WAFER BASED ON LAO SUBSTRATE

HERSTELLUNGSVERFAHREN VON EINEM UNPOLAREN BLAU-LED-EPITAXIALWAFER AUF DER BASIS EINES LAO-SUBSTRATS

PROCÉDÉ DE PRÉPARATION D'UNE TRANCHE ÉPITAXIALE DE DEL BLEUE NON POLAIRE BASÉE SUR UN SUBSTRAT LAO


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 24.03.2014 CN 201410112151

(43)Date of publication of application:
21.12.2016 Bulletin 2016/51

(73)Proprietor: Shanghai Chiptek Semiconductor Technology Co., Ltd.
Qingpu District Shanghai 201799 (CN)

(72)Inventors:
  • CAI, Zhuoran
    Shanghai 200083 (CN)
  • GAO, Hai
    Shanghai 200083 (CN)
  • LIU, Zhi
    Shanghai 200083 (CN)
  • YIN, Xianglin
    Shanghai 200083 (CN)
  • LIU, Zhengwei
    Shanghai 20062 (CN)

(74)Representative: Loo, Chi Ching et al
Albright IP Limited County House Bayshill Road
Cheltenham, Gloucestershire GL50 3BA
Cheltenham, Gloucestershire GL50 3BA (GB)


(56)References cited: : 
EP-A2- 1 562 237
CN-A- 1 761 080
CN-A- 101 901 761
CN-A- 103 296 159
CN-U- 203 760 505
US-A1- 2009 008 648
US-A1- 2013 240 876
WO-A1-2010/020077
CN-A- 1 881 625
CN-A- 103 268 911
CN-A- 103 311 100
CN-U- 203 850 326
US-A1- 2012 171 797
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Field of the Invention



    [0001] The present invention relates to an LED epitaxial wafer and a preparation method thereof, and in particular, to a non-polar blue light LED epitaxial wafer based on an LAO substrate and a preparation method thereof.

    Background of the Invention



    [0002] At present, substrates of LED blue light epitaxial wafers are mainly sapphire. The LED technology based on a sapphire substrate has two serious problems. Firstly, the mismatch rate of the sapphire and a GaN crystal lattice is as high as 17%. Such high lattice mismatch results in a high defect density of the sapphire based LED epitaxial wafer, thereby greatly influencing the luminous efficiency of an LED chip. Secondly, the price of the sapphire substrate is very high, resulting in very high production cost of a nitride LED.

    [0003] Another major reason for the low luminous efficiency of the LED chip is that the current GaN based LEDs in wide use have polarity. At present, the most ideal material for manufacturing of a high efficient LED device is GaN. The GaN is of a closely packed hexagonal crystal structure, whose crystal faces are divided into a polar face, which is a c face [(0001) face] and non-polar faces, which include an a face [(11-20) face] and an m face [(1-100) face]. Currently, most GaN based LEDs are constructed based on the polar face of the GaN. On the polar face of the GaN, the centroid of the Ga atom cluster does not coincide with the centroid of the N atom cluster, thus forming an electric dipole and generating a spontaneous polarization field and a piezoelectric polarization field, and further, causing a Quantum-confined Stark effect (QCSE). The QCSE causes electrons being separated from holes, and reduces the radiation recombination efficiency of charge carriers, which in turn influences the luminous efficiency of LED, and causes instability of a light emitting wavelength of the LED.

    [0004] EP 1562237 A2 relates to Nitride-based semiconductor light emitting device and its method of manufacturing. CN 103268911 A relates to p-NiO/n-ZnO heterojunction light-emitting device and its preparation method. CN 203760505 U relates to apparatus for non-polar blue light LED epitaxial wafers for LAO substrates. US 2013/0240876 A1 relates to a method of growing a non-polar plane epitaxy layer of wurtzite structure. WO 2010/020077 A1 relates to a method of fabricating InGaAlN light-emitting device on a combined substrate. CN 103296159 A discloses InGaN/GaN multiple quantum well growing on La0.3Sr1.7AlTaO6 substrate and manufacturing method of InGaN/GaN multiple quantum well. US 2009/0008648 A1 discloses a GaN-based semiconductor element which can suppress a leakage current generated during reverse bias application.

    Summary of the Invention



    [0005] The technical problem to be solved by the present invention is to provide a non-polar blue light LED epitaxial wafer based on an LAO substrate and a preparation method thereof. The non-polar blue light LED epitaxial wafer has the advantages of low defect density, good crystalline quality and good luminous performance, and having low preparation cost.

    [0006] The technical solution used for solving the above technical problem of the present invention is to provide a non-polar blue light LED epitaxial wafer based on an LAO substrate, including the substrate. The substrate is the LAO substrate, and a buffer layer, a first non-doped layer, a first doped layer, a quantum well layer, an electron barrier layer and a second doped layer are sequentially arranged on the LAO substrate.

    [0007] According to the non-polar blue light LED epitaxial wafer based on the LAO substrate, the buffer layer is a non-polar m face GaN buffer layer, the first non-doped layer is a non-polar non-doped u-GaN layer, the first doped layer is a non-polar n-type doped GaN film, the quantum well layer is a non-polar InGaN/GaN quantum well layer, the electron barrier layer is a non-polar m face AlGaN electron barrier layer, and the second doped layer is a non-polar p-type doped GaN film.

    [0008] To solve the above technical problem, the present invention provides a preparation method of a non-polar blue light LED epitaxial wafer based on an LAO substrate, including the following steps: a) adopting the LAO substrate, selecting the crystal orientation, and cleaning the surface of the LAO substrate; b) annealing the LAO substrate, and forming an AlN seed crystal layer on the surface of the LAO substrate; and c) sequentially forming a non-polar m face GaN buffer layer, a non-polar non-doped u-GaN layer, a non-polar n-type doped GaN film, a non-polar InGaN/GaN quantum well, a non-polar m face AlGaN electron barrier layer and a non-polar p-type doped GaN film on the LAO substrate by adopting metal organic chemical vapor deposition.

    [0009] According to the above preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate, wherein the step b) includes the following processes: baking the LAO substrate at high temperature of 900-1200°C for 1-4 h followed by cooling to the room temperature in air, then passing N2 plasma to keep the temperature for 30-80 minutes, and forming the AlN seed crystal layer on the surface of the LAO substrate by radio frequency plasma enhanced metal organic chemical vapor deposition, wherein the flow of the N plasma is 40-90 sccm, and the radio frequency power for generating the plasma nitrogen is 200-500W.

    [0010] According to the above preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate, wherein in the step c), the process of forming the non-polar m face GaN buffer layer may be as follows: cooling the LAO substrate to 400-800°C, passing TMGa and the N plasma, and controlling the pressure of a reaction chamber within the range of 53329 - 93326 Pa, the flow of the N plasma within the range of 40-90 sccm, the radio frequency power of generating the plasma nitrogen within the range of 200-700W, and the V/III ratio within the range of 800-1200.

    [0011] According to the above preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate, wherein in the step c), the process of forming the non-polar non-doped u-GaN layer may be as follows: controlling the temperature of the LAO substrate with the range of 1000-1500°C, passing the TMGa, controlling the pressure of the reaction chamber at 53329 Pa and the V/III ratio at 180.

    [0012] According to the above preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate, wherein in the step c), the process of forming the non-polar n-type doped GaN film may be as follows: controlling the temperature of the LAO substrate within the range of 1000-1300°C, passing the TMGa and SiH4, maintaining the flow of the SiH4 within the range of 60-100 sccm, and controlling the pressure of the reaction chamber at 31997 Pa, the V/III ratio at 160, and the dopped electron concentration within the range of 1.0×1017 to 5.3×1019cm-3.

    [0013] According to the above preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate, wherein in the step c), the process of forming the non-polar InGaN/GaN quantum well may be as follows:

    forming a barrier layer: controlling the temperature of the LAO substrate within the range of 750-950°C, closing H2, passing the TEGa and ammonia gas, and controlling the pressure of the reaction chamber at 26664 Pa, the V/III ratio at 986, and the thickness within the range of 10-15nm; and

    forming a well layer: controlling the temperature of the LAO substrate within the range of 750-950°C, closing H2, passing the TEGa, TMIn and the ammonia gas, and controlling the pressure of the reaction chamber at 26664 Pa, the V/III ratio at 1439, and the thickness within the range of 2-4nm.



    [0014] According to the above preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate, wherein in the step c), the process of forming the non-polar m face AlGaN electron barrier layer may be as follows: rising the temperature of the LAO substrate to 900-1050°C, passing the TMGa and the ammonia gas, and controlling the pressure of the reaction chamber at 26664 Pa and the V/III ratio at 986.

    [0015] According to the above preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate, wherein in the step c), the process of forming the non-polar p-type doped GaN film may be as follows: controlling the temperature of the LAO substrate within the range of 900-1100°C, passing the TMGa, CP2Mg and the ammonia gas, maintaining the flow of the CP2Mg at 250-450 sccm, and controlling the pressure of the reaction chamber at 26664 Pa, the V/III ratio within the range of 1000-1250, and the hole doping concentration within the range of 1.0×1016 to 2.2×1018cm-3.

    [0016] Compared with the prior art, the present invention has the following beneficial effects that: according to the non-polar blue light LED epitaxial wafer based on the LAO substrate and the preparation method thereof provided by the present invention, the LAO substrate is adopted, and the buffer layer, the first non-doped layer, the first doped layer, the quantum well layer, the electron barrier layer and the second doped layer are arranged on the LAO substrate in sequence, so that the non-polar blue light LED epitaxial wafer has the advantages of low defect density, good crystalline quality and good luminous performance, and have low preparation cost.

    Brief Description of the Drawings



    [0017] 

    Fig.1 is a schematic diagram of a structure of a non-polar blue light LED epitaxial wafer based on an LAO substrate of the present invention;

    Fig.2 is a schematic diagram of a structure of a preparation device for a non-polar blue light LED epitaxial wafer based on an LAO substrate of the present invention;

    Fig.3 is a schematic flow chart of a preparation of a non-polar blue light LED epitaxial wafer based an LAO substrate of the present invention;

    Fig.4 is an XRD test diagram of a non-polar blue light LED epitaxial wafer grown on a (001) face of an LAO substrate of the present invention;

    Fig.5 is a PL spectrum test diagram of a non-polar m face blue light LED epitaxial wafer grown on an LAO substrate of the present invention at the room temperature;

    Fig.6 is an EL spectrum test diagram of a non-polar m face blue light LED epitaxial wafer grown on an LAO substrate of the present invention at the room temperature.


    Detailed Description of the Embodiments



    [0018] The present invention will be further described below in combination with accompany drawings and embodiments.

    [0019] Fig.1 is a schematic diagram of a structure of a non-polar blue light LED epitaxial wafer based on an LAO substrate of the present invention.

    [0020] Please refer to Fig.1. The non-polar blue light LED epitaxial wafer based on the LAO substrate provided by the present invention includes a substrate. The substrate is the LAO substrate, and a buffer layer, a first non-doped layer, a first doped layer, a quantum well layer, an electron barrier layer and a second doped layer are arranged on the LAO substrate in sequence. According to the non-polar blue light LED epitaxial wafer grown on the LAO substrate provided by the present invention, the LAO substrate is also called a lanthanum aluminum oxide substrate which is composed of La, A1 and O elements, and the molecular formula is LaAlxOy. As shown in Fig.1, the non-polar blue light LED epitaxial wafer provided by the present invention includes an LAO substrate 10, a non-polar m face GaN buffer layer 11, a non-polar non-doped u-GaN layer 12, a non-polar n-type doped GaN film 13, a non-polar InGaN/GaN quantum well layer 14, a non-polar m face AlGaN electron barrier layer 15 and a non-polar p-type doped GaN film 16, which are arranged from bottom to top in sequence.

    [0021] Fig.2 is a schematic diagram of a structure of a preparation device for a non-polar blue light LED epitaxial wafer based on an LAO substrate of the present invention.

    [0022] Please refer to Fig.2. 20 and 21 respectively represent NH3 and SiH4, which are used for providing N and Si; 22 represents H2, which is used as a carrier gas and for conveying Cp2Mg, TMGa and TMIn; 23, 24 and 25 respectively represent the Cp2Mg, the TMGa and the TMIn, which are used for providing Mg, Ga and In necessary for the growth of LED; 26 represents is a mechanical arm, which is used for conveying the substrate and a sample; 27 represents a radio frequency induction heater, which is used for heating and controlling the temperature of the substrate; 28 represents a graphite plate, which is used for bearing the LAO substrate; 29 represents a reaction chamber, which is used for generating chemical reactions on various reactant gases to generate the LED; 30 represents a spray head, which is a device used for uniformly jetting the fully mixed reactant gases onto the surface of the substrate; 31 represents a radio frequency plasma source device, which is used for providing active N; and 32-40 represent valves, which are used for controlling the gas conveyance states of various pipelines. MFC represents a flow controller, which is used for controlling the gas flow to meet the growth demands.

    [0023] Fig.3 is a schematic flow chart of a preparation of a non-polar blue light LED epitaxial wafer based an LAO substrate of the present invention.

    [0024] Please refer to Fig.3. the preparation method of the non-polar blue light LED epitaxial wafer grown on the LAO substrate of the present invention specifically includes the following steps:

    step S 1: adopting the LAO substrate, selecting the crystal orientation, and cleaning the surface of the LAO substrate;

    step S2: annealing the LAO substrate, and forming an AlN seed crystal layer on the surface of the LAO substrate; and

    step S3: sequentially forming a non-polar m face GaN buffer layer, a non-polar non-doped u-GaN layer, a non-polar n-type doped GaN film, a non-polar InGaN/GaN quantum well, a non-polar m face AlGaN electron barrier layer and a non-polar p-type doped GaN film on the LAO substrate by metal organic chemical vapor deposition.



    [0025] A specific embodiment is provided below with the preparation steps and process conditions as follows:
    1. (1) adopting an LAO substrate, and selecting the crystal orientation;
    2. (2) cleaning the surface of the substrate;
    3. (3) annealing the substrate: baking the substrate at high temperature of 900-1200 °C for 1-4 h followed by cooling the substrate to the room temperature in air, then passing N2 plasma to keep the temperature for 30-80 minutes, and forming an AlN seed crystal layer on the surface of the substrate to provide a template for the growth of a GaN film, wherein the flow of the N plasma is 40-90 sccm, and the radio frequency power for generating the plasma nitrogen is 200-500W;
    4. (4) growing a non-polar m face GaN buffer layer by radio frequency (RF) plasma enhanced metal organic chemical vapor deposition (MOCVD), wherein the process conditions are as follows: the substrate is cooled to 400-800°C, the TMGa and the N plasma are passed, the pressure of a reaction chamber is 53329 - 93326 Pa, the flow of the N plasma is 40-90 sccm, the radio frequency power of generating the plasma nitrogen is 200-700W, and the V/III ratio is 800-1200;
    5. (5) growing a non-polar non-doped u-GaN layer by the MOCVD process, wherein the process conditions are as follows: the temperature of the substrate is 1000-1500°C, the TMGa is passed, the pressure of the reaction chamber is 53329 Pa, and the V/III ratio is 180;
    6. (6) growing a non-polar n-type doped GaN film by the MOCVD process, wherein the process conditions are as follows: the temperature of the substrate is 1000-1300°C, the TMGa and SiH4 are passed, the flow of the SiH4 is maintained at 60-100 sccm, the pressure of the reaction chamber is 26664 Pa, the V/III ratio is 160, and the doped electron concentration is 1.0×1017 to 5.3×1019cm-3;
    7. (7) growing a non-polar InGaN/GaN quantum well by the MOCVD process, wherein the process conditions for forming a barrier layer are as follows: , the temperature of the LAO substrate is 750-950 °C, H2 is closed, the TEGa and ammonia gas are passed, the pressure of the reaction chamber is 26664 Pa, the V/III ratio is 986, and the thickness is 10-15nm; and wherein the process conditions for forming a well layer are as follows: the temperature of the LAO substrate is 750-950 °C, H2 is closed, the TEGa, TMIn and the ammonia gas are passed, the pressure of the reaction chamber is 26664 Pa, the V/III ratio is 1439, and the thickness is 2-4nm;
    8. (8) growing a non-polar m face AlGaN electron barrier layer by the MOCVD process, wherein the process conditions are as follows: the temperature of the LAO substrate is raised to 900-1050°C, the TMGa and the ammonia gas are passed, the pressure of the reaction chamber is 26664 Pa, and the V/III ratio is 986; and
    9. (9) growing a non-polar p-type doped GaN film by the MOCVD process, wherein the process conditions are as follows: the temperature of the LAO substrate is 900-1100°C, the TMGa, CP2Mg and the ammonia gas are passed, the flow of the CP2Mg is maintained at 250-450 sccm, the pressure of the reaction chamber is 26664 Pa, the V/III ratio is 1000-1250, and the doped hole concentration is 1.0×1016 to 2.2×1018cm-3.


    [0026] Fig.4 is an XRD test diagram of a non-polar blue light LED epitaxial wafer grown on a (001) face of an LAO substrate of the present invention.

    [0027] Fig.4 shows a full width at half maximum (FWHM) value of a X ray rocking curve of the LED epitaxial wafer as tested in the present invention. The full width at half maximum (FWHM) value is less than 0.1 degree, which indicates that the non-polar blue light LED epitaxial wafer prepared in the present invention has very good performance no matter on defect density or on crystalline quality.

    [0028] Fig.5 is a PL spectrum test diagram of a non-polar m face blue light LED epitaxial wafer grown on an LAO substrate of the present invention at the room temperature. Fig.5 shows a emission peak having a wavelength of 460nm, and the full width at half maximum of 23nm, as tested by a PL spectrum at a temperature of 293K in the present invention. This indicates that the non-polar GaN film prepared in the present invention has very good performance on optical properties.

    [0029] Fig.6 is an EL spectrum test diagram of a non-polar m face blue light LED epitaxial wafer grown on an LAO substrate of the present invention at the room temperature.

    [0030] Fig.6 shows a emission peak having a wavelength of 461nm, the full width at half maximum of 22nm and the output power of 7.8mw@20mA, as tested by an EL spectrum at the temperature of 293K in the present invention. This indicates that the non-polar GaN film prepared in the present invention has very good performance on electrical properties.

    [0031] In summary, the present invention provides a non-polar blue light LED epitaxial wafer based on the LAO substrate and the preparation method thereof. The LAO substrate is adopted, and the non-polar m face GaN buffer layer, the non-polar non-doped u-GaN layer, the non-polar n-type doped GaN film, the non-polar InGaN/GaN quantum well, the non-polar m face AlGaN electron barrier layer and the non-polar p-type doped GaN film are arranged on the LAO substrate in sequence. Compared with the prior art, the present invention has the advantages of simple growth process and low preparation cost, and the non-polar blue light LED epitaxial wafer prepared has the advantages of low defect density, good crystalline quality and good electrical and optical performances.


    Claims

    1. A preparation method of a non-polar blue light LED epitaxial wafer based on a LAO substrate, the wafer having a LAO substrate (10), and a non-polar m face GaN buffer layer (11), a first non-polar non-doped u-GaN layer (12), a first non-polar n-type doped GaN film layer (13), a non-polar InGaN/GaN quantum well layer (14), a non-polar m face AlGaN electron barrier layer (15) and a second non-polar p-type doped GaN film layer (16) being sequentially arranged on the LAO substrate (10), wherein the method comprises the following steps:

    a) adopting the LAO substrate (10), selecting the crystal orientation, and cleaning the surface of the LAO substrate (10);

    b) annealing the LAO substrate (10), and forming an AlN seed crystal layer on the surface of the LAO substrate (10); and

    c) sequentially forming the non-polar m face GaN buffer layer (11), the first non-polar non-doped u-GaN layer (12), the first non-polar n-type doped GaN film (13), the non-polar InGaN/GaN quantum well layer (14), the non-polar m face AlGaN electron barrier layer (15) and the second non-polar p-type doped GaN film layer (16) on the LAO substrate (10) by adopting metal organic chemical vapor deposition; characterised in that said step b) comprises the following process:

    baking the LAO substrate (10) at high temperature of 900-1200 °C for 1-4 h followed by cooling to the room temperature in air, then passing N2 plasma to keep the temperature for 30-80 minutes, and forming the AlN seed crystal layer on the surface of the LAO substrate (10) by radio frequency plasma enhanced metal organic chemical vapor deposition, the flow of the N plasma is 40-90 sccm, and the radio frequency power for generating the plasma nitrogen is 200-500W.


     
    2. The preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate according to claim 1, wherein in said step c), the process of forming the non-polar m face GaN buffer layer (11) is as follows: cooling the LAO substrate (10) to 400-800 °C, passing TMGa and the N plasma, and controlling the pressure of a reaction chamber within the range of 53329 - 93326 Pa, the flow of the N plasma within the range of 40-90 sccm, the radio frequency power of generating the plasma nitrogen within the range of 200-700W, and the V/III ratio within the range of 800-1200.
     
    3. The preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate according to claim 1, wherein in said step c), the process of forming the non-polar non-doped u-GaN layer (12) is as follows: controlling the temperature of the LAO substrate (10) with the range of 1000-1500 °C, passing the TMGa, controlling the pressure of the reaction chamber at 53329 Pa and the V/III ratio at 180.
     
    4. The preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate according to claim 1, wherein in said step c), the process of forming the non-polar n-type doped GaN film layer (13) is as follows: controlling the temperature of the LAO substrate (10) within the range of 1000-1300 °C, passing the TMGa and SiH4, maintaining the flow of the SiH4 within the range of 60-100 sccm, and controlling the pressure of the reaction chamber at 31997 Pa, the V/III ratio at 160, and the dopped electron concentration within the range of 1.0×1017 to 5.3×1019cm-3.
     
    5. The preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate according to claim 1, wherein in said step c), the process of forming the non-polar InGaN/GaN quantum well layer (14) includes:

    forming a barrier layer: controlling the temperature of the LAO substrate (10) within the range of 750-950 °C, closing H2, passing the TEGa and ammonia gas, and controlling the pressure of the reaction chamber at 26664 Pa, the V/III ratio at 986, and the thickness within the range of 10-15nm; and

    forming a well layer: controlling the temperature of the LAO substrate (10) within the range of 750-950 °C, closing H2, passing the TEGa, TMIn and the ammonia gas, and controlling the pressure of the reaction chamber at 26664 Pa, the V/III ratio at 1439, and the thickness within the range of 2-4nm.


     
    6. The preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate according to claim 1, wherein in said step c), the process of forming the non-polar m face AlGaN electron barrier layer (15) is as follows:

    rising the temperature of the LAO substrate (10) to 900-1050 °C, passing the TMGa and the ammonia gas, and controlling the pressure of the reaction chamber at 26664 Pa and the V/III ratio at 986.


     
    7. The preparation method of the non-polar blue light LED epitaxial wafer based on the LAO substrate according to claim 1, wherein in said step c), the process of forming the non-polar p-type doped GaN film layer (16) is as follows: controlling the temperature of the LAO substrate (10) within the range of 900-1100 °C, passing the TMGa, CP2Mg and the ammonia gas, maintaining the flow of the CP2Mg at 250-450 sccm, and controlling the pressure of the reaction chamber at 26664 Pa, the V/III ratio within the range of 1000-1250, and the hole doping concentration within the range of 1.0×1016 to 2.2×1018cm-3.
     


    Ansprüche

    1. Herstellungsverfahren von einem unpolaren Blau-LED-Epitaxialwafer auf der Basis eines LAO-Substrats, wobei der Wafer ein LAO-Substrat (10) und eine unpolare m-Facetten-GaN-Pufferschicht (11), eine erste unpolare, nicht dotierte u-GaN-Schicht (12), eine erste unpolare, n-dotierte GaN-Filmschicht (13), eine unpolare InGaN/GaN-Quantum-Well-Schicht (14), eine unpolare m-Facetten-AlGaN-Elektronenbarriereschicht (15) und eine zweite unpolare, p-dotierte GaN-Filmschicht (16) aufweist, die aufeinanderfolgend auf dem LAO-Substrat (10) angeordnet sind, wobei das Verfahren die folgenden Schritte umfasst:

    a) Vorsehen des LAO-Substrats (10), Auswählen der Kristallorientierung und Reinigen der Oberfläche des LAO-Substrats (10);

    b) Tempern des LAO-Substrats (10) und Bilden einer AlN-Impfkristallschicht auf der Oberfläche des LAO-Substrats (10); und

    c) aufeinanderfolgendes Bilden der unpolaren m-Facetten-GaN-Pufferschicht (11), der ersten unpolaren, nicht dotierten u-GaN-Schicht (12), des ersten unpolaren, n-dotierten GaN-Films (13), der unpolaren InGaN/GaN-Quantum-Well-Schicht (14), der unpolaren m-Facetten-AlGaN-Elektronenbarriereschicht (15) und der zweiten unpolaren, p-dotierten GaN-Filmschicht (16) auf dem LAO-Substrat (10) durch Anwenden einer metallorganischen chemischen Gasphasenabscheidung;

    dadurch gekennzeichnet, dass der Schritt b) den folgenden Prozess umfasst:

    Einbrennen des LAO-Substrats (10) bei hoher Temperatur von 900-1200 °C über 1-4 h, gefolgt von Abkühlen auf die Raumtemperatur in Luft, dann Durchleiten von N2-Plasma, um die Temperatur über 30-80 Minuten zu halten, und Bilden der AlN-Impfkristallschicht auf der Oberfläche des LAO-Substrats (10) durch HF-plasmaverstärkte metallorganische chemische Gasphasenabscheidung, wobei die Strömungsrate des N-Plasmas 40-90 Standardkubikzentimeter pro Minute ist, und die Hochfrequenzleistung zum Erzeugen des Plasmastickstoffs 200-500 W ist.


     
    2. Herstellungsverfahren von dem unpolaren Blau-LED-Epitaxialwafer auf der Basis des LAO-Substrats nach Anspruch 1, wobei in dem Schritt c) der Prozess zum Bilden der unpolaren m-Facetten-GaN-Pufferschicht (11) wie folgt stattfindet: Abkühlen des LAO-Substrats (10) auf 400-800 °C, Durchleiten von TMGa und des N-Plasmas und Einstellen des Drucks einer Reaktionskammer in den Bereich von 53329-93326 Pa, der Strömungsrate des N-Plasmas in den Bereich von 40-90 Standardkubikzentimeter pro Minute, der Hochfrequenzleistung zum Erzeugen des Plasmastickstoffs in dem Bereich von 200-700 W und des V/III-Verhältnisses in dem Bereich von 800-1200.
     
    3. Herstellungsverfahren von dem unpolaren Blau-LED-Epitaxialwafer auf der Basis des LAO-Substrats nach Anspruch 1, wobei in dem Schritt c) der Prozess des Bildens der unpolaren, nicht dotierten u-GaN-Schicht (12) wie folgt stattfindet: Einstellen der Temperatur des LAO-Substrats (10) in den Bereich von 1000-1500 °C, Durchleiten des TMGa, Einstellen des Drucks der Reaktionskammer auf 53329 Pa und des V/III-Verhältnisses auf 180.
     
    4. Herstellungsverfahren von dem unpolaren Blau-LED-Epitaxialwafer auf der Basis des LAO-Substrats nach Anspruch 1, wobei in dem Schritt c) der Prozess des Bildens der unpolaren, n-dotierten GaN-Filmschicht (13) wie folgt stattfindet: Einstellen der Temperatur des LAO-Substrats (10) in den Bereich von 1000-1300 °C, Durchleiten des TMGa und des SiH4, Halten der Strömungsrate des SiH4 in dem Bereich von 60-100 Standardkubikzentimeter pro Minute und Einstellen des Drucks der Reaktionskammer auf 31997 Pa, des V/III-Verhältnisses auf 160 und der dotierten Elektronenkonzentration in den Bereich von 1,0 x 1017 bis 5,3 x 1019 cm-3.
     
    5. Herstellungsverfahren von dem unpolaren Blau-LED-Epitaxialwafer auf der Basis des LAO-Substrats nach Anspruch 1, wobei in dem Schritt c) der Prozess des Bildens der unpolaren, InGaN/GaN-Quantum-Well-Schicht (14) Folgendes umfasst:

    Bilden einer Barriereschicht: Einstellen der Temperatur des LAO-Substrats (10) in den Bereich von 750-950 °C, Beenden von H2, Durchleiten des TEGa und von Ammoniakgas und Einstellen des Drucks der Reaktionskammer auf 26664 Pa, des V/III-Verhältnisses auf 986 und der Dicke in den Bereich von 10-15 nm; und

    Bilden einer Well-Schicht: Einstellen der Temperatur des LAO-Substrats (10) in den Bereich von 750-950 °C, Beenden von H2, Durchleiten des TEGa, TMIn und des Ammoniakgases und Einstellen des Drucks der Reaktionskammer auf 26664 Pa, des V/III-Verhältnisses auf 1439 und der Dicke in den Bereich von 2-4 nm.


     
    6. Herstellungsverfahren von dem unpolaren Blau-LED-Epitaxialwafer auf der Basis des LAO-Substrats nach Anspruch 1, wobei in dem Schritt c) der Prozess des Bildens der unpolaren, m-Facetten-AlGaN-Elektronenbarriereschicht (15) wie folgt stattfindet:

    Erhöhen der Temperatur des LAO-Substrats (10) auf 900-1050 °C, Durchleiten des TMGa und des Ammoniakgases und Einstellen des Drucks der Reaktionskammer auf 26664 Pa und des V/III-Verhältnisses auf 986.


     
    7. Herstellungsverfahren von dem unpolaren Blau-LED-Epitaxialwafer auf der Basis des LAO-Substrats nach Anspruch 1, wobei in dem Schritt c) der Prozess des Bildens der unpolaren, p-dotierten GaN-Filmschicht (16) wie folgt stattfindet: Einstellen der Temperatur des LAO-Substrats (10) in den Bereich von 900-1100 °C, Durchleiten des TMGa, CP2Mg und des Ammoniakgases, Halten der Strömungsrate des CP2Mg auf 250-450 Standardkubikzentimeter pro Minute und Einstellen des Drucks der Reaktionskammer auf 26664 Pa, des V/III-Verhältnisses in den Bereich von 1000-1250 und der Lochdotierungskonzentration in den Bereich von 1,0 x 1016 bis 2,2 x 1018 cm-3.
     


    Revendications

    1. Procédé de préparation d'une tranche épitaxiale de LED à lumière bleue non polarisée basé sur un substrat de LAO, la tranche contenant un substrat de LAO (10) et une couche tampon de GaN à faces m non polaires (11), une première couche d'u-GaN non polaire et non dopée (12), une première couche de film de GaN non polaire dopé de type n (13), une couche non polaire de puits quantique InGaN/GaN (14), une couche non polaire barrière électronique AlGaN à faces m (15) et une seconde couche non polaire de film de GaN dopé de type p (16) qui sont disposées successivement sur le substrat de LAO (10), le procédé comprenant les étapes suivantes :

    a) l'adoption du substrat de LAO (10), la sélection de l'orientation des cristaux et le nettoyage de la surface du substrat de LAO (10) ;

    b) le recuit du substrat de LAO (10) et la formation d'une couche de cristaux à germes AlN sur la surface du substrat de LAO (10) ; et

    c) la formation successive de la couche tampon de GaN à faces m non polaires (11), de la première couche d'u-GaN non polaire et non dopée (12), de la première couche de film de GaN non polaire dopé de type n (13), de la couche non polaire de puits quantique InGaN/GaN (14), de la couche non polaire barrière électronique AlGaN à faces m (15) et de la seconde couche non polaire de film de GaN dopé de type p (16) sur le substrat de LAO (10) par adoption d'un dépôt chimique de vapeur organométallique, caractérisé en ce que ladite étape b) comprend le processus suivant :

    cuisson du substrat de LAO (10) à haute température de 900 à 1 200 °C pendant 1 à 4 h suivie d'un refroidissement jusqu'à température ambiante dans l'air, puis passage de plasma de N2 pour maintenir la température pendant 30 à 80 minutes, et formation de la couche de cristaux à germes d'AlN sur la surface du substrat de LAO (10) par dépôt chimique de vapeur organométallique améliorée par plasma à radiofréquence, le flux de plasma d'azote vaut 40 à 90 sccm, et la puissance de radiofréquence permettant de produire l'azote de plasma vaut de 200 à 500 W.


     
    2. Procédé de préparation de la tranche épitaxiale de LED à lumière bleue non polarisée basé sur un substrat de LAO selon la revendication 1, dans lequel dans ladite étape c), le processus de formation de la couche tampon de GaN à faces m non polaires (11) a lieu comme suit : refroidissement du substrat de LAO (10) à 400 à 800 °C, passage de TMGa et du plasma d'azote et régulation de la pression d'une chambre de réaction dans l'intervalle allant de 53 329 à 93 326 Pa, le flux du plasma d'azote dans l'intervalle allant de 40 à 90 sccm, la puissance de radiofréquence de production de l'azote de plasma dans l'intervalle allant de 200 à 700 W, et le rapport V/III dans l'intervalle allant de 800 à 1 200.
     
    3. Procédé de préparation de la tranche épitaxiale de LED à lumière bleue non polarisée basé sur un substrat de LAO selon la revendication 1, dans lequel dans ladite étape c), le processus de formation de la couche d'u-GaN non polaire et non dopée (12) a lieu comme suit : régulation de la température du substrat de LAO (10) dans l'intervalle de 1 000 à 1 500 °C, passage de TMGa, régulation de la pression de la chambre de réaction à 53 329 Pa et le rapport V/III dans l'intervalle à 180.
     
    4. Procédé de préparation de la tranche épitaxiale de LED à lumière bleue non polarisée basé sur un substrat de LAO selon la revendication 1, dans lequel dans ladite étape c), le processus de formation de la couche de film de GaN non polaire dopé de type n (13) a lieu comme suit: régulation de la température du substrat de LAO (10) dans l'intervalle de 1 000 à 1 300 °C, passage de TMGa et de SiH4, maintien du débit de SiH4 dans l'intervalle allant de 60 à 100 sccm et régulation de la pression de la chambre de réaction à 31 997 Pa, le rapport V/III à 160 et la concentration en électrons dopés dans l'intervalle allant de 1,0.1017 à 5,3.1019 cm-3.
     
    5. Procédé de préparation de la tranche épitaxiale de LED à lumière bleue non polarisée basé sur un substrat de LAO selon la revendication 1, dans lequel dans ladite étape c), le processus de formation de la couche non polaire de puits quantique InGaN/GaN (14) comprend : la formation d'une couche barrière : la régulation de la température du substrat de LAO (10) dans l'intervalle allant de 750 à 950 °C, l'arrêt du H2, le passage du TEGa et de l'ammoniac gazeux et la régulation de la pression de la chambre réactionnelle à 26 664 Pa, du rapport V/III à 986 et de l'épaisseur dans l'intervalle de 10 à 15 nm ; et
    la formation d'une couche de puits : la régulation de la température du substrat de LAO (10) dans l'intervalle allant de 750 à 950 °C, l'arrêt du H2, le passage du TEGa, du TMIn et de l'ammoniac gazeux et la régulation de la pression de la chambre réactionnelle à 26 664 Pa, du rapport V/III à 1439 et de l'épaisseur dans l'intervalle de 2 à 4 nm.
     
    6. Procédé de préparation de la tranche épitaxiale de LED à lumière bleue non polarisée basé sur un substrat de LAO selon la revendication 1, dans lequel dans ladite étape c), le processus de formation de la couche non polaire barrière électronique AlGaN à faces m (15) a lieu comme suit : élévation de la température du substrat de LAO (10) de 900 à 1 050 °C, passage de TMGa et de l'ammoniac gazeux et régulation de la pression de la chambre de réaction à 26 664 Pa et du rapport V/III dans l'intervalle à 986.
     
    7. Procédé de préparation de la tranche épitaxiale de LED à lumière bleue non polarisée basé sur un substrat de LAO selon la revendication 1, dans lequel dans ladite étape c), le processus de formation de la couche non polaire de film de GaN dopé de type p (16) a lieu comme suit: régulation de la température du substrat de LAO (10) dans l'intervalle allant de 900 à 1 100 °C, passage de TMGa, du CP2Mg et de l'ammoniac gazeux, maintien du débit de CP2Mg à 250 à 450 sccm et régulation de la pression de la chambre de réaction à 26 664 Pa, du rapport V/III dans l'intervalle allant de 1 000 à 1 250 et la concentration en électrons dopés dans l'intervalle allant de 1,0.1016 à 2,2.1018 cm-3.
    de la concentration de dopage de trou dans l'intervalle allant de 1,0.1016 à 2,2.1018 cm-3.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description