Developement of a new modulation spectroscopy by exciting polarized light

我们开发了一种利用偏振各向异性调制半导体量子结构的新技术。我们主要研究偏振光调制的反射信号。下面是对本研究的总结。(1)为了建立一种分析方法，我们从理论上研究了半导体表面的介电函数。(2)我们开发了一种新的原位表征系统来观察晶体生长过程中的电子态。探针光照射样品表面，检测偏振调制信号。发现探针光的入射角对观察表面电子态有重要影响。(3)探测光的p波和s波具有各向异性，这反映了表面形貌和表面重构引起的介电函数的各向异性。这实现了一种新的对表面电子态的敏感探测。利用这种技术，我们可以观察到突变表面和吸附原子所改变的电子态。(4)系统可以测量调制频谱及其生长过程中的动态特性。该技术有望实现原位调制光谱学的实际应用。

We developed a new modulation technique for semiconductor quantum structures by using polarization anisotropy. We focus our attention on reflectance signal modulated by polarized light. The summary of this research are followed. (1) In order to develope an analysis method, we theoretically investigated dielectric functions at semiconductor surfaces. (2) We developed a new in-situ characterization system to observe electronic states during the crystal growth. A probe light irradiate the sample surface, and the polarization modulated signal was detected. It was found that the incident angle of the probe light is important to observe the surface electronic states. (3) An anisotropic character was observed for the p and s waves of the probe light, which reflect the anisotropy of the dielectric function coming from surface morphology and surface reconstructions.This realizes a new sensitive detection of electronic states localized at the surface. By using this technique, we can observe the electronic states changed by the abrupt surface and adsorped atoms. (4) Our developed system can measure a modulation spectrum and its dynamic character during the growth. This technique promises a practical use of the in-situ modulation spectroscopy.