Developement of a new modulation spectroscopy by exciting polarized light

我们利用极化各向异性发展了一种新的半导体量子结构调制技术。我们将注意力集中在偏振光调制的反射信号上。以下是对本研究的总结。(1)为了发展一种分析方法，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。用探针光照射样品表面，检测到偏振调制信号。研究发现，探测光的入射角对观察表面电子态是重要的。(3)探测光的p波和S波具有各向异性，反映了表面形貌和表面重构引起的介电函数的各向异性，实现了对表面电子态的一种新的灵敏检测。利用这一技术，我们可以观察到原子的突变表面和吸附原子引起的电子态的变化。(4)我们研制的系统可以测量晶体生长过程中的调制光谱及其动态特性。这项技术为原位调制光谱的实际应用奠定了基础。

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.