光谱学与光谱分析
光譜學與光譜分析
광보학여광보분석
SPECTROSCOPY AND SPECTRAL ANALYSIS
2014年
2期
327-330
,共4页
代爽%于彤军%李兴斌%袁刚成%路慧敏
代爽%于彤軍%李興斌%袁剛成%路慧敏
대상%우동군%리흥빈%원강성%로혜민
InGaN/GaN多量子阱蓝光发光二极管%老化%电致发光谱%极化电场
InGaN/GaN多量子阱藍光髮光二極管%老化%電緻髮光譜%極化電場
InGaN/GaN다양자정람광발광이겁관%노화%전치발광보%겁화전장
InGaN/GaN blue LEDs%Degradation%Electroluminescence spectra%Polarization field
系统地研究了小注入电流(<4mA)下InGaN/GaN多量子阱结构蓝光发光二极管的发光光谱特性在老化过程中的变化。对比老化前后的电致发光(EL)光谱,发现在注入电流1mA下的峰值波长(peakwavelength)和半高宽(FWHM)随老化时间增加而减小,变化过程分两个阶段:前期(<100h)减小速度较快,而后逐渐变缓,呈现出与LEDs的发光光功率一致的变化规律,说明LEDs的等效极化电场在老化过程中减弱,这一变化和量子阱内缺陷的增加有明确的关系。通过电学特性测量发现同一结电压(Vj=1.8V)下的结电容Cj和由交流小信号I-V方法计算得到的注入电流1mA下的结电压Vj随老化时间增加而增大,明确了在同等小注入电流下量子阱内的载流子浓度随老化过程增加。分析表明在老化过程中InGaN/GaN多量子阱结构蓝光发光二极管量子阱内的缺陷及其束缚的载流子数量增加,形成了增强的极化电场屏蔽效应,减弱的等效极化电场导致了量子阱的能带倾斜变小,带边辐射复合能量增大,能态密度增多,对应的发光过程的峰值波长变短(蓝移),半高宽变窄。
繫統地研究瞭小註入電流(<4mA)下InGaN/GaN多量子阱結構藍光髮光二極管的髮光光譜特性在老化過程中的變化。對比老化前後的電緻髮光(EL)光譜,髮現在註入電流1mA下的峰值波長(peakwavelength)和半高寬(FWHM)隨老化時間增加而減小,變化過程分兩箇階段:前期(<100h)減小速度較快,而後逐漸變緩,呈現齣與LEDs的髮光光功率一緻的變化規律,說明LEDs的等效極化電場在老化過程中減弱,這一變化和量子阱內缺陷的增加有明確的關繫。通過電學特性測量髮現同一結電壓(Vj=1.8V)下的結電容Cj和由交流小信號I-V方法計算得到的註入電流1mA下的結電壓Vj隨老化時間增加而增大,明確瞭在同等小註入電流下量子阱內的載流子濃度隨老化過程增加。分析錶明在老化過程中InGaN/GaN多量子阱結構藍光髮光二極管量子阱內的缺陷及其束縳的載流子數量增加,形成瞭增彊的極化電場屏蔽效應,減弱的等效極化電場導緻瞭量子阱的能帶傾斜變小,帶邊輻射複閤能量增大,能態密度增多,對應的髮光過程的峰值波長變短(藍移),半高寬變窄。
계통지연구료소주입전류(<4mA)하InGaN/GaN다양자정결구람광발광이겁관적발광광보특성재노화과정중적변화。대비노화전후적전치발광(EL)광보,발현재주입전류1mA하적봉치파장(peakwavelength)화반고관(FWHM)수노화시간증가이감소,변화과정분량개계단:전기(<100h)감소속도교쾌,이후축점변완,정현출여LEDs적발광광공솔일치적변화규률,설명LEDs적등효겁화전장재노화과정중감약,저일변화화양자정내결함적증가유명학적관계。통과전학특성측량발현동일결전압(Vj=1.8V)하적결전용Cj화유교류소신호I-V방법계산득도적주입전류1mA하적결전압Vj수노화시간증가이증대,명학료재동등소주입전류하양자정내적재류자농도수노화과정증가。분석표명재노화과정중InGaN/GaN다양자정결구람광발광이겁관양자정내적결함급기속박적재류자수량증가,형성료증강적겁화전장병폐효응,감약적등효겁화전장도치료양자정적능대경사변소,대변복사복합능량증대,능태밀도증다,대응적발광과정적봉치파장변단(람이),반고관변착。
The luminescence spectra of InGaN/GaN multiple quantum wells light-emitting diodes under low level injection current (<4 mA) during aging process was investigated for the first time .Comparing the electroluminescence (EL) spectra of LEDs be-fore and after aging time it was found that the peak wavelength and the full width at half maximum (FWHM ) decreased with stress time and the changes of EL spectrum had two different stages -drastic decrease at the early stress stage and slow decrease later showing the same trend with the output optical power of LEDs ,which indicates that the effective polarization electric field of LEDs becomes weak during the aging process and the change has a clear correlation with the increase of the defects in the mul-tiple quantum wells of LEDs .Electrical measurement revealed that junction capacitance (Cj ) under the same junction voltage (Vj=1.8 V) and the junction voltage (Vj ) with the same injection current 1 mA calculated by ac small-signal IV method increased along with aging time ,which explicates that the carrier density under the same low injection increases as the aging time increa-ses .Analyses indicate that the polarization field in the quantum well is more seriously screened by the increased carriers captured by defects activated during stress time ,the weaker effective polarization electric field makes the tilt of the energy band smaller , the energy radiated through the band edge and the density of energy states of the band edge increase which leads to the behaviors of peak wavelength and the FWHM of InGaN/GaN multiple quantum wells LEDs under low level injection current .