Characterization of Defects in Semiconductors by Raman Spectroscopy in Low Frequency Region

本课题的目的是利用半导体低频区域的拉曼测量来检测晶体缺陷或缺陷。为此，我们利用多通道探测器对以下两种光谱系统进行了比较。(1)滤光光谱仪和双单色仪的组合。(2)全息陷波滤光片和双单色器的组合。第一个系统可以应用于任何波长的激发激光，但滤光光谱仪的反射损失非常高。因此，该系统不便于低频微弱信号的检测。结果表明，第二种系统的信号损失较小，拉曼光谱可以测量到60 cm^<-1>的范围内。当使用拉曼显微镜时，拉曼光谱测量到100 cm^<-1>。用第二系统测量了具有层错的SiC晶体的拉曼光谱，并对其进行了分析。

The aim of this project is to detect crystal defects or imperfections by Raman measurements of semiconductors in low frequency region. For this purpose, we have compared following two spectroscopic systems by use of a multichannel detector.(1) A combination of a filtered spectrometer and double monochromator.(2) A combination of a holographic notch filter and a double monochromator.The first system can be applied to any wavelengths of an exciting laser, but the reflection loss of the filter spectrometer was very high. Hence this system could not be convenient for the detection of weak signals in lower frequency region.It was found that the loss of signals in the second system was low and that the Raman spectra could be measured in the region down to 60 cm^<-1>. When using a Raman microscope, Raman spectra were measured down to 100 cm^<-1>.Raman spectra of SiC crystals having stacking faults were measured by the second system and analyzed.