量子阱层和垒层具有不同Al组分的270/290/330nm AlGaN基深紫外LED光电性能
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摘要
为了研究AlGaN量子阱层和垒层中Al组分不同对AlGaN基深紫外发光二极管(LED)光电性能的影响,本文利用MOCVD生长、光刻和干法刻蚀工艺制备了AlGaN量子阱层和垒层具有不同Al组分的270/290/330nm深紫外LED,通过实验和数值模拟计算方法发现,量子阱层和垒层中具有低Al组分紫外LED的AlGaN材料具有较低的位错密度、较高的光输出功率和外量子效率。通过电流-电压(I-V)曲线拟合出的较大的理想因子(>3.5)和能带结构图表明,AlGaN深紫外LED的电流产生是隧穿机制占据主导作用,这是因为高Al组分AlGaN量子阱中强极化场造成了有源层区域较大的能带弯曲和电势降。
The optical and electrical properties of 270 /290 /330 nm AlGaN-based deep ultraviolet( UV) light-emitting diodes( LEDs) with different Al content in quantum wells and barriers were investigated systematically. Based on the experimental and numerical study,It is observed that the UV LEDs with longer wavelength and lower Al composition in AlGaN multiple quantum wells( MQWs)possess less dislocation density,higher light output power and internal quantum efficiency. The large ideality factors calculated from I-V curves and simulated energy band profiles indicate that the current in the deep UV LEDs with high Al content is dominated by tunneling mechanism,which is attribute to the resulting potential drop in the active region caused by large polarization field in AlGaN MQWs.
The optical and electrical properties of 270 /290 /330 nm AlGaN-based deep ultraviolet( UV) light-emitting diodes( LEDs) with different Al content in quantum wells and barriers were investigated systematically. Based on the experimental and numerical study,It is observed that the UV LEDs with longer wavelength and lower Al composition in AlGaN multiple quantum wells( MQWs)possess less dislocation density,higher light output power and internal quantum efficiency. The large ideality factors calculated from I-V curves and simulated energy band profiles indicate that the current in the deep UV LEDs with high Al content is dominated by tunneling mechanism,which is attribute to the resulting potential drop in the active region caused by large polarization field in AlGaN MQWs.
引文
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[22]LEE K B,PARBROOK P J,WANG T,et al..The origin of the high ideality factor in Al Ga N-based quantum well ultraviolet light emitting diodes[J].Phys.Stat.Sol.(b),2010,247(7):1761-1763.
[23]PIPREK J,LI S.Electron leakage effects on Ga N-based light-emitting diodes[J].Opt.Quant.Electron.,2010,42(2):89-95.
[24]YANG G F,LI G H,GAO S M,et al..Characteristics of N-face In Ga N light-emitting diodes with p-type In Ga N/Ga N superlattice[J].IEEE Photon.Technol.Lett.,2013,25(23):2369-2372.
[25]FIORENTINI V,BERNARDINI F,SALA F D,et al..Effects of macroscopic polarization inⅢ-Ⅴnitride multiple quantum wells[J].Phys.Rev.B,1999,60(12):8849-8858.
[26]VURGAFTMAN I,MEYER J R,RAM-MOHAN L R.Band parameters forⅢ-Ⅴcompound semiconductors and their alloys[J].J.Appl.Phys.,2001,89(11):5815-5875.
[2]KHAN A,BALAKRISHNAN K,KATONA T.Ultraviolet light-emitting diodes based on group three nitrides[J].Nat.Photon.,2008,2(2):77-84.
[3]FISCHER A J,ALLERMAN A A,CRAWFORD M H,et al..Room-temperature direct current operation of 290 nm lightemitting diodes with milliwatt power levels[J].Appl.Phys.Lett.,2004,84(17):3394-3396.
[4]SHATALOV M,SUN W H,LUNEV A,et al..Al Ga N deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%[J].Appl.Phys.Express,2012,5(8):082101-1-3.
[5]HIRAYAMA H,YATABE T,NOGUCHI N,et al..231-261 nm Al Ga N deep-ultraviolet light-emitting diodes fabricated on Al N multilayer buffers grown by ammonia pulse-flow method on sapphire[J].Appl.Phys.Lett.,2007,91(7):071901-1-3.
[6]HUANG M F,LU T H.Optimization of the active-layer structure for the deep-UV Al Ga N light-emitting diodes[J].IEEE J.Quant.Electron.,2006,42(8):820-826.
[7]李杨,冯列峰,李丁,等.半导体Ga N基蓝光发光二极管的精确电学特性[J].光电子·激光,2013,24(4):663-668.LI Y,FENG L F,LI D,et al..Accurate electrical properties of semiconductor Ga N blue light emitting diodes at large forward bias voltage[J].J.Optoelectron.·Laser,2013,24(4):663-668.(in Chinese)
[8]KIM K H,FAN Z Y,KHIZAR M,et al..Al Ga N-based ultraviolet light-emitting diodes grown on Al N epilayers[J].Appl.Phys.Lett.,2004,85(20):4777-4779.
[9]SCHUBERT M F,XU J R,KIM J K,et al..Polarization-matched Ga In N/Al Ga In N multi-quantum-well light-emitting diodes with reduced efficiency droop[J].Appl.Phys.Lett.,2008,93(4):041102-1-3.
[10]ZHANG J C,ZHU Y H,EGAWA T,et al..Suppression of the subband parasitic peak by 1 nm i-Al N interlayer in Al Ga N deep ultraviolet light-emitting diodes[J].Appl.Phys.Lett.,2008,93(13):131117-1-3.
[11]GUTT R,PASSOW T,KUNZER M,et al..Al Ga N-based 355 nm UV light-emitting diodes with high power efficiency[J].Appl.Phys.Express,2012,5(3):032101-1-3.
[12]樊晶美,王良臣,刘志强.表面粗化对Ga N基垂直结构LED出光效率的影响[J].光电子·激光,2009,20(8):994-996.FAN J M,WANG L C,LIU Z Q.The influence of surface roughening on Ga N based vertical-electrodes LEDs[J].J.Optoelectron.·Laser,2009,20(8):994-996.(in Chinese)
[13]SUN Q,YAN W,FENG M X,et al..Ga N-on-Si blue/white LEDs:eptaxy,chip,and package[J].J.Semicond.,2016,37(4):044006.
[14]吴震,钱可元,韩彦军,等.高效率、高可靠性紫外LED封装技术研究[J].光电子·激光,2007,18(1):1-4.WU Z,QIAN K Y,HAN Y J,et al..Study on packaging technology of ultraviolet LED with high efficiency and reliability[J].J.Optoelectron.·Laser,2006,18(1):1-4.(in Chinese)
[15]杜帅,张方辉.基于液晶衬垫的OLED光萃取[J].光电子·激光,2016,27(4):380-385.DU S,ZHANG F H.OLED light extraction based on liquid crystal spacer[J].J.Optoelectron.·Laser,2016,27(4):380-385.(in Chinese)
[16]GHERASIMOVA M,CUI G,REN Z,et al..Heteroepitaxial evolution of Al N on Ga N grown by metal-organic chemical vapor deposition[J].J.Appl.Phys.,2004,95(5):2921-2923.
[17]YANG Y,CAO X A,YAN C H.Investigation of the nonthermal mechanism of efficiency rolloff in In Ga N light-emitting diodes[J].IEEE Trans.Electron Dev.,2008,55(7):1771-1775.
[18]CHEN K X,DAI Q,LEE W,et al..Effect of dislocations on electrical and optical properties of n-type Al0.34Ga0.66N[J].Appl.Phys.Lett.,2008,93(19):192108-1-3.
[19]RYU H Y,CHOI I G,CHOI H S,et al..Investigation of light extraction efficiency in Al Ga N deep-ultraviolet light-emitting diodes[J].Appl.Phys.Express,2013,6(6):062101-1-4.
[20]LI Y,CHEN S C,TIAN W,et al.Advantages of Al Ga N-based 310-nm UV light-emitting diodes with Al content graded Al Ga N electron blocking layers[J].IEEE Photon.J.,2013,5(4):8200309-1-10.
[21]WITTE H,ROHRBECK A,GNTHER K M,et al..Electrical investigations of Al Ga N/Al N structures for LEDs on Si(111)[J].Phys.Stat.Sol.(a),2011,208(7):1597-1599.
[22]LEE K B,PARBROOK P J,WANG T,et al..The origin of the high ideality factor in Al Ga N-based quantum well ultraviolet light emitting diodes[J].Phys.Stat.Sol.(b),2010,247(7):1761-1763.
[23]PIPREK J,LI S.Electron leakage effects on Ga N-based light-emitting diodes[J].Opt.Quant.Electron.,2010,42(2):89-95.
[24]YANG G F,LI G H,GAO S M,et al..Characteristics of N-face In Ga N light-emitting diodes with p-type In Ga N/Ga N superlattice[J].IEEE Photon.Technol.Lett.,2013,25(23):2369-2372.
[25]FIORENTINI V,BERNARDINI F,SALA F D,et al..Effects of macroscopic polarization inⅢ-Ⅴnitride multiple quantum wells[J].Phys.Rev.B,1999,60(12):8849-8858.
[26]VURGAFTMAN I,MEYER J R,RAM-MOHAN L R.Band parameters forⅢ-Ⅴcompound semiconductors and their alloys[J].J.Appl.Phys.,2001,89(11):5815-5875.