半绝缘GaAs的双调制反射光谱研究

发布时间：2018-05-12 23:02

本文选题：双调制反射光谱 + 半绝缘GaAs　；参考：《物理学报》2017年14期

【摘要】：半导体材料电子能带结构的确定对研究其物理性质及其在半导体器件方面的应用有重要意义.光调制反射光谱是一种无损和高灵敏度的表征半导体材料电子能带结构的光学手段.光调制反射光谱中激光调制导致的材料介电函数的变化在联合态密度奇点附近表现得更为明显.通过测量这些变化,可以得到有关材料能带结构临界点的信息.然而在传统的单调制反射光谱中,激光调制信号的光谱线型拟合和临界点数目的分析往往被瑞利散射和荧光信号所干扰.本文将双调制技术与双通道锁相放大器结合,消除了瑞利信号和荧光信号的干扰,获得了具有较高信噪比的调制反射光谱信号.双通道锁相放大器可以同时解调出反射光谱信号及其经泵浦激光调制后的细微变化量,避免了多次采集时可能存在的系统误差.利用这种技术,在可见激光(2.33 eV)泵浦下,我们测量了半绝缘GaAs体材料从近红外至紫外波段(1.1-6.0 eV)的双调制反射光谱,获得了多个能带结构临界点的信息.探测到了高于泵浦能量之上的与GaAs能带结构高阶临界点对应的特征光谱信号,说明带隙以上高阶临界点的光调制反射光谱本质是光生载流子对内建电场的调制,并不是来自该临界点附近的能带填充效应.这一结果表明双调制反射光谱能够对半导体材料能带结构带隙及其带隙以上临界点进行更准确的表征.
[Abstract]:The determination of the electronic band structure of semiconductor materials is of great significance for the study of its physical properties and its application in semiconductor devices. The optical modulation reflection spectrum is an optical means of nondestructive and highly sensitive characterization of the electronic band structure of semiconductor materials. The dielectric function changes of the material caused by laser modulation in the light modulated reflection spectrum. By measuring these changes, the information about the critical points of the material band structure can be obtained by measuring these changes. However, in the traditional monotone reflectance spectra, the spectral line fitting and the analysis of the critical points for the laser modulated signals are often disturbed by the Rayleigh scattering and the fluorescence signals. The dual modulation technique combined with the dual channel phase locked amplifier eliminates the interference of the Rayleigh signal and the fluorescence signal. The modulation reflection spectrum signal with high signal to noise ratio is obtained. The dual channel phase locked amplifier can simultaneously remove the reflection spectrum signal and the fine change after the pump laser modulation, thus avoiding the possibility of storing in multiple acquisition. With this technique, using this technique, we measured the semi insulating GaAs body material from the near infrared to the ultraviolet band (1.1-6.0 eV) with the dual modulation reflectance spectra under the visible laser (2.33 eV) pump, and obtained the information of the critical points of the band structure. The corresponding higher critical points of the GaAs energy band structure above the pump energy were detected. The characteristic spectral signal shows that the optical modulation reflection spectrum of the high order critical point above the band gap is essentially the modulation of the built electric field by the photogenerated carrier, and not the band filling effect near the critical point. This result shows that the dual modulation reflection spectrum can carry on the band gap and the critical point above the band gap of the semiconductor material. More accurate representation.

【作者单位】：中国科学院半导体研究所半导体超晶格国家重点实验室;中国科学院大学材料科学与光电技术学院;南通大学江苏省专用集成电路设计重点实验室;
【基金】：国家自然科学基金(批准号:61474067,11474277,11434010) 国家重点研发计划(批准号:2016YFA0301204)资助的课题~~
【分类号】：TN304.23

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