基于金属掺杂ITO透明导电层的紫外LED制备
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摘要
为降低ITO薄膜对紫外波段的光吸收,制备低电压高功率的紫外LED,研究了一种基于金属掺杂ITO透明导电层的365nm紫外LED的制备工艺。利用1cm厚的石英片生长了不同厚度ITO薄膜以及在ITO上掺杂不同金属的新型薄膜,并研究了在不同的退火条件下这种薄膜的电阻和透过率,分析了掺杂金属ITO薄膜的带隙变化。将这种掺杂的ITO薄膜生长在365nm外延片上并完成电极生长,制备成14mil×28mil的正装LED芯片。利用电致发光(EL)设备对LED光电性能进行测试并对比。实验结果表明:掺Al金属的ITO薄膜能够相对ITO薄膜的带隙提高0.15eV。在600℃退火后,方块电阻降低6.2Ω/□,透过率在356nm处达到90.8%。在120mA注入电流下,365nmLED的电压降低0.3V,功率提高14.7%。ITO薄膜掺金属能够影响薄膜带隙,改变紫光LED光电性能。
In order to reduce the optical absorption of ITO thin films to UV waveband and to prepare low voltage as well as high power ultraviolet LEDs,the preparation process of 365 nm UV LED based on metal-doped ITO( Metal-ITO) transparent conductive layer was studied. The ITO thin films of different thickness and doped with different metals on ITO layer were grown by using 1 cm thickness quartz substrate,and the resistance and transmittance of the films were studied under different annealing conditions. The change of bandgap of Metal-ITO thin films was analyzed. Then,the MetalITO thin films were grown on 365 nm epitaxial wafers and completed the electrode growth,14 mil × 28 mil formal LEDs were prepared. Finally,the photoelectric properties of LED with Electroluminescence( EL) equipment were tested and compared. The experimental results show that the bandgap of Al-ITO thin film can be increased by 0. 15 eV compared with that of ITO thin film. After annealing at 600 ℃,the square resistance is reduced by 6. 2 Ω/□ and the transmittance is 90. 8%. At 120 m A injection current,the decrease of voltage of 365 nm LED is 0. 3 V and the increase of lightoutput power is 14. 7%. So,the Metal-ITO film can influence the bandgap of the film and along with the change of photoelectric performance of UV LED.
In order to reduce the optical absorption of ITO thin films to UV waveband and to prepare low voltage as well as high power ultraviolet LEDs,the preparation process of 365 nm UV LED based on metal-doped ITO( Metal-ITO) transparent conductive layer was studied. The ITO thin films of different thickness and doped with different metals on ITO layer were grown by using 1 cm thickness quartz substrate,and the resistance and transmittance of the films were studied under different annealing conditions. The change of bandgap of Metal-ITO thin films was analyzed. Then,the MetalITO thin films were grown on 365 nm epitaxial wafers and completed the electrode growth,14 mil × 28 mil formal LEDs were prepared. Finally,the photoelectric properties of LED with Electroluminescence( EL) equipment were tested and compared. The experimental results show that the bandgap of Al-ITO thin film can be increased by 0. 15 eV compared with that of ITO thin film. After annealing at 600 ℃,the square resistance is reduced by 6. 2 Ω/□ and the transmittance is 90. 8%. At 120 m A injection current,the decrease of voltage of 365 nm LED is 0. 3 V and the increase of lightoutput power is 14. 7%. So,the Metal-ITO film can influence the bandgap of the film and along with the change of photoelectric performance of UV LED.
引文
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[22]KIM M J,KIM T G.Fabrication of metal-deposited indium tin oxides:its applications to 385 nm light-emitting diodes[J].ACS Appl.Mater.Interf.,2016,8(8):5453-5457.
[23]HASHIM F S.Effect of Li doping on structure and optical energy gap of Ni O films prepared by sol-gel technique[J].J.KUFA-Phys.,2015,7:985-990.
[24]罗远晟,陈松林,马平,等.膜厚对ITO薄膜的电学与光学性质的影响[J].压电与声光,2010(6):1024-1026.LUO Y S,CHEN S L,MA P,et al..Influence of film thickness on electrical and optical properties of ITO thin films[J].Piezoelect.Acousto-Opt.,2010(6):1024-1026.(in Chinese)
[25]江锡顺,万东升,宋学萍,等.退火温度对ITO薄膜微结构和光电特性的影响[J].人工晶体学报,2011,40(6):1536-1540.JIANG X S,WAN D S,SONG X P,et al..Effects of annealing temperature on the microstructure and photoelectric properties of ITO thin films[J].J.Intraocular Cryst.,2011,40(6):1536-1540.(in Chinese)
[26]蔡琪,曹春斌,江锡顺,等.ITO薄膜的微结构表征及其组分特性[J].真空科学与技术学报,2007(3):195-199.CAI Q,CAO C B,JIANG X S,et al..Microstructure characterization and component properties of ITO thin films[J].J.Vac.Sci.Technol.,2007(3):195-199.(in Chinese)
[27]CHANDRAMOHAN S,KANJILAL A,STRACHE T,et al..Modifications in structural and optical properties of Mn-ion implanted Cd S thin films[J].Appl.Surf.Sci.,2009,256(2):465-468.
[28]TEOLIS B D,LEOFFLER M J,RAUT U,et al..Infrared reflectance spectroscopy on thin films:interference effects[J].Icarus,2007,190(1):274-279.
[29]MOHAMMADIJOO M,KHORSHIDIA Z N,SADRHEZHAAD S K,et al..Synthesis and characterization of nickel oxide nanoparticle with wide band gap energy prepared via thermochemical processing[J].J.Nanosci.Nanotechnol.,2014,4(1):6-9.
[2]张源涛,张宝林,刘明哲,等.6H-SiC衬底上Al Ga N基垂直结构紫外LED的制备[J].发光学报,2017,38(6):753-759.ZHANG Y T,ZHANG B L,LIU M Z,et al..Fabrication of Al Ga N based vertical structure UV LED on 6H-SiC substrate[J].Chin.J.Lumin.,2017,38(6):753-759.(in Chinese)
[3]MORI M,HAMAMOTO A,TAKAHASHI A,et al..Development of a new water sterilization device with a 365 nm UV-LED[J].Med.Biolog.Eng.Comput.,2007,45(12):1237-1241.
[4]MURAMOTO Y,KIMURA M,NOUDA S.Development and future of ultraviolet light-emitting diodes~UV-LED will replace UV lamp[J].Semicond.Sci.Technol.,2014,29(8):084004.
[5]CAI D,WANG H,HUANG Y,et al..Completely transparent Ohmic electrode on p-type Al Ga N for UV LEDs with coreshell Cu@alloy nanosilk network[J].SPIE,2016,9926:99260D.
[6]HOSONO H.Recent progress in transparent oxide semiconductors:Materials and device application[J].Thin Solid Films,2007,515(15):6000-6014.
[7]HIRAYAMA H,TAKANO T,SAKAI J,et al..Realization of over 10%EQE Al Ga N deep-UV LED by using transparent p-AlGaN contact layer[J].SPIE,10104:doi:10.1117/12.2254100.
[8]CHEN M,WANG X,YU Y H,et al..X-ray photoelectron spectroscopy and Auger electron spectroscopy studies of Aldoped Zn O films[J].Appl.Surf.Sci.,2000,158(1):134-140.
[9]TUN C J,SHEU J K,PONG B J,et al..Enhanced light output of Ga N-based power LEDs with transparent Al-doped Zn Ocurrent spreading layer[J].IEEE Photonics Technol.Lett.,2005,18(1):274-276.
[10]刘立伟,邢振远,牛亮,等.基于石墨烯的透明导电电极及其制法与应用:中国,CN101859858A[P].2010-10-13.LIU L W,XING Z Y,NIU L,et al..The preparation and application of transparent conductive electrode based on graphene:China,CN101859858A[P].2010-10-13.(in Chinese)
[11]JEONG H,JEONG S Y,PARK D J,et al..Suppressing spontaneous polarization of p-GaN by graphene oxide passivation:augmented light output of Ga N UV-LED[J].Sci.Rep.,2015,5:7778.
[12]PARK J,KIM J,KIM J,et al..Hybrid indium tin oxide/Ag nanowire electrodes for improving the light output power of near ultraviolet Al Ga N-based light-emitting diode[J].Curr.Appl.Phys.,2016,16(5):545-548.
[13]KIM J,PARK J,NA J,et al..Using agglomerated Ag grid to improve the light output of near ultraviolet Al Ga N-based light-emitting diode[J].Microelectron.Eng.,2017,169:29-33.
[14]WOO K Y,KIM K H,KIM T G.Performance of In Ga N/Al Ga In N Near-UV LEDs with ni/Ga2O3/Ag/Ga2O3electrode[J].IEEE Photon.Technol.Lett.,2016,28(1):67-70.
[15]TAKEHARA K,TAKEDA K,ITO S,et al..Indium--tin oxide/Al reflective electrodes for ultraviolet light-emitting diodes[J].Jpn.J.Appl.Phys.,2012,51(4):42101.
[16]KIM J,LEE J.Electrical and optical properties of near UV transparent conductive ITO/Ga2O3multilayer films deposited by RF magnetron sputtering[J].Appl.Phys.Lett.,2016,109(17):172107.
[17]LIN Y H,LIU Y S,LIU C Y.Light output enhancement of near UV-LED by using Ti-doped ITO transparent conducting layer[J].IEEE Photonics Technol.Lett.,2010,22(19):1443-1445.
[18]DONG J C,KIM D Y,KIM T G,et al..Al Ga N-based ultraviolet light-emitting diodes using fluorine-doped indium tin oxide electrodes[J].Appl.Phys.Lett.,2012,100:081110.
[19]KULKARNI A K,KNICHERBOCHER S A.Estimation and verification of the electrical properties of indium tin oxide based on the energy band diagram[J].J.Vac.Sci.Technol.,1996,14(3):1709-1713.
[20]HASNIP P J,REFSON K,PROBERT M I J,et al..Density functional theory in the solid state[J].Philosoph.Trans.,2014,372(2011):20130270.
[21]CHOI W K,HO V,NG V,et al..Germanium diffusion and nanocrystal formation in silicon oxide on silicon substrate under rapid thermal annealing[J].Appl.Phys.Lett.,2005,86(14):1398.
[22]KIM M J,KIM T G.Fabrication of metal-deposited indium tin oxides:its applications to 385 nm light-emitting diodes[J].ACS Appl.Mater.Interf.,2016,8(8):5453-5457.
[23]HASHIM F S.Effect of Li doping on structure and optical energy gap of Ni O films prepared by sol-gel technique[J].J.KUFA-Phys.,2015,7:985-990.
[24]罗远晟,陈松林,马平,等.膜厚对ITO薄膜的电学与光学性质的影响[J].压电与声光,2010(6):1024-1026.LUO Y S,CHEN S L,MA P,et al..Influence of film thickness on electrical and optical properties of ITO thin films[J].Piezoelect.Acousto-Opt.,2010(6):1024-1026.(in Chinese)
[25]江锡顺,万东升,宋学萍,等.退火温度对ITO薄膜微结构和光电特性的影响[J].人工晶体学报,2011,40(6):1536-1540.JIANG X S,WAN D S,SONG X P,et al..Effects of annealing temperature on the microstructure and photoelectric properties of ITO thin films[J].J.Intraocular Cryst.,2011,40(6):1536-1540.(in Chinese)
[26]蔡琪,曹春斌,江锡顺,等.ITO薄膜的微结构表征及其组分特性[J].真空科学与技术学报,2007(3):195-199.CAI Q,CAO C B,JIANG X S,et al..Microstructure characterization and component properties of ITO thin films[J].J.Vac.Sci.Technol.,2007(3):195-199.(in Chinese)
[27]CHANDRAMOHAN S,KANJILAL A,STRACHE T,et al..Modifications in structural and optical properties of Mn-ion implanted Cd S thin films[J].Appl.Surf.Sci.,2009,256(2):465-468.
[28]TEOLIS B D,LEOFFLER M J,RAUT U,et al..Infrared reflectance spectroscopy on thin films:interference effects[J].Icarus,2007,190(1):274-279.
[29]MOHAMMADIJOO M,KHORSHIDIA Z N,SADRHEZHAAD S K,et al..Synthesis and characterization of nickel oxide nanoparticle with wide band gap energy prepared via thermochemical processing[J].J.Nanosci.Nanotechnol.,2014,4(1):6-9.