Characterization of optical and thermal properties of chalcopyrite compound semiconductors by photoacoustic spectroscopy

在本研究项目中，我们研究了光声光谱在多元化合物半导体光学和热学性质表征中的应用。我们采用了气体传声器方法作为测量方法，分析了测量这些材料的光吸收系数和热扩散率的条件。得到了以下结果：1.在使用厚度小于2 mm的板状硫化镉样品的情况下，实验结果与基于RG理论的理论结果吻合较好。对于厚度大于2 mm的试件，实验结果与理论计算结果存在较大差异。研究了一种更好的测量粉末光声光谱的方法。将被测粉末稀释到透明基质粉末中的稀释法比用未稀释粉末样品的稀释法要好。通过考虑样品内部发声的理论，我们发现理论结果与实验结果有很好的一致性。与炭素样品的光吸收信号进行了比较，得到了粉末材料的光吸收系数。研究了CuGaS_2、TlGaSe_2、TlInS_2的光声光谱，并结合这些半导体的光电导谱和透射谱进行了研究。

In this research project, we have investigated an application of photoacoustic spectroscopy to characterization of optical and thermal properties of multinary compound semiconductors. We employed a gas-microphone method as a measurement method, and analyzed the conditions to evaluate the optical absorption coefficients and the thermal diffusivities of these materials. Following results are obtained.1. In the case of using plate type CdS specimen having the thickness less than 2mm, we have good agreement between experimental results and theoretical ones based on the RG theory. For the specimens having thickness larger than 2mm, the difference between the experimental results and the theoretical ones was observed.2. A better technique for the measurements of the photoacoustic spectra of powders was investigated. The dilution method where a powder to be measured is diluted in a transparent matrix powder is found to be better than that with an undiluted powder sample. By means of the theory including sounds coming from the inside parts of the specimen, we have found a good agreement of the theoretical results with the experimental results. To compare with the PA signal of carbon specimen, the optical absorption coefficients of powdered materials were obtained.3. Photoacoustic spectra of CuGaS_2, TlGaSe_2, TlInS_2 were investigated in conjunction with photoconductivity spectra and transmission spectra of these semiconductors.