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Investigation of Optical Absorption Spectra of Extremely Thin Semiconductor Quantum Structure by a Piezoelectric Photothermal Spectroscopy

利用压电光热光谱研究极薄半导体量子结构的光学吸收光谱

基本信息

批准号：
15560020
负责人：
IKARI Tetsuo
金额：
$ 2.37万
依托单位：
UNIVERSITY OF MIYAZAKI
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Optical absorption spectrum for GaInNAs/GaAs single quantum well structure was obtained precisely by means of our developed Piezoelectric Photothermal Spectroscopy(PPTS) with taking into account a photovoltaic effect. Since the thickness of the sample was extremely thin, usual absorption measurement technique was useless. Detailed analysis of the spectra gave us clear understandings both for two dimensional densities of states of the quantum levels in the conduction and valence bands and exciton formations. Since the present results made possible for precise fitting the line shape of the exciton absorption by a quasi-Voigt function, the binding energies of the exciton were accurately determined as a function of the well thickness and measuring temperature. Theoretical consideration for the binding energy and blue shift of the critical energies of the quantum levels were also carried out. We found that effective mass difference between inside and outside the quantum well and band offset ratio in the conduction band played important roles for generating the PPT spectra. Since the non-radiative intra-band transition determines the temperature dependence of the intensities of the PPT signal, we found the non-radiative transition pathways in the strained quantum well structures. At the same time, we could investigate the oxygen vacancies in the transparent conducting oxidize ZnO and the proton irradiation induced defect in chalcopyrite semiconductor thin films by using the present PPTS methodology. These results in this project make clear that the PPTS technology is a new and effective optical technique for investigating the quantum structure, including the wires and the dots, of the semiconductor devices.

利用自行研制的考虑光伏效应的压电光热谱仪（PPTS）精确地获得了GaInNAs/GaAs单量子阱结构的光吸收谱。由于样品的厚度非常薄，通常的吸收测量技术是无用的。对谱的详细分析使我们对导带和价带量子能级的二维态密度和激子的形成有了清楚的了解。由于目前的结果可以精确拟合的准Voigt函数的激子吸收的线形，激子的结合能被准确地确定为阱厚度和测量温度的函数。对量子能级的结合能和临界能蓝移进行了理论计算。我们发现量子阱内外的有效质量差和导带的带偏移比对产生PPT谱起着重要的作用。由于非辐射带内跃迁决定了PPT信号强度的温度依赖性，我们在应变量子阱结构中发现了非辐射跃迁途径。同时，利用该方法还可以研究透明导电氧化物ZnO中的氧空位和黄铜矿半导体薄膜中的质子辐照缺陷。这些结果表明，PPTS技术是研究半导体器件量子结构（包括线和点）的一种新的有效的光学技术。