摘要
用光的反射光谱和光的光致发光光谱的测量对Ga0.69In0.31NxAs1-x/GaAs的单量子阱的光学特性作了研究,在单量子阱的反射光谱中,观察到GaAs能隙之上的Franz-Keldysh振荡和来源于量子阱区的各种类激子跃迁, Franz-Keldysh振荡确定量子阱的内建电场并发现它是随N的浓度增加而增加;反射信号随样品中氮耦合增强而减弱,因为温度降低时载流子的定域作用导致调制效应的弱化。激子跃迁的能量和温度关系按照Varshni和爱因斯坦-玻司方程作了研究,在PL谱中观察到的11 H跃迁能量和谱线展宽的温度反常关系解释为起源于氮耦合所引起的定域态,这种样品的谱线特征为随氮成份增加出现红移,氮结合作用的另一个结果是晶体的性质严重退化,明显地表现线宽受温度的影响增大。总之,氮引进系统会观察到GaAs边带以上的FkO导致内建场增大,有低温时高激发态叠加并屏闭在定域态上的部分调制外场作用的倾向。PL峰能量和线宽对温度的反常关系可以理解为由氮的结合作用引起的形成定域态和去除定域态的竞争结果。
The optical properties of Ga0.69In0. 31NxAs1-x/GaAs single quantum well （SQW） structures have been studied using photoreflectance （PR） and photoluminescence （PL） measurements. In the PR spectra of single quantum well （SQW） samples, clear Franz-Keldysh oscillations （FKOs） above the GaAs band edge and the various excitonic transitions originating from the quantum well （QW） region have been observed. The built-in electric field in the SQW has been determined from FKOs and found to increase with N concentration. The PR signal has been found to decrease for nitrogen incorporated samples when the temperature was lowered due to a weakening of the modulation efficiency induced by carrier localization. The temperature dependence of the exciton transition energies have been studied in terms of both the Varshni and Bose-Einstein equations. The temperature dependence analysis yields information on the parameters that describe the temperature variations of the interband transitions. The anomalous temperature dependent 11H transition energy and linewidth observed in the PL spectra have been explained as originating from the localized states as a result of nitrogen incorporation. The spectral features of these samples showed red shift with increasing N composition x. Another consequence of N-incorporation is the severe degradation of the crystal quality as evidenced by a significant increase in the temperature independent broadening parameter. In addition, introducing N into the system also resulted in an increase in the builtin electric field as determined from the observed FKOs above the GaAs band edge which tends to increase the overlap integrals of the higher excited states as well as partially screening out the modulating external field on the localized states at low temperature.
The anomalous behavior of the temperature dependence of the PL peak energy and the full width at half maximum （FWHM） can be understood as a result of competition between the delocalized states and the localized states
出处
《电子器件》
CAS
2008年第1期52-56,共5页
Chinese Journal of Electron Devices
基金
The author T. H. Chen gratefully aeknowledge the support of the Technology and Science Institute of Northern Taiwan.
关键词
单量子井
光激反射
光激发光
Franz-Keldysh振动
FWHM
Single quantum well （SQW）
Photoreflectance （PR）
Photoluminescence （PL）
Franz-Keldysh oscillations （FKOs）
Full width at half maximum （FWHM）
