Material Properties of GaAsPSb
Date Issued
2012
Date
2012
Author(s)
Tsai, Han-Sheng
Abstract
In this thesis, we use secondary ion mass spectroscopy to acquire mole fractions of our samples; Using high resolution X-ray diffraction to do the reciprocal space mapping, and obtain the information about lattice structure; Using Extended X-ray absorption fine structure experiment to investigate the information about bond length. Besides, we calculate valence force field model to the result of Extended X-ray absorption fine structure experiment; In order to acquire a reasonable set of data from EXAFS experiment, we construct a data selection process; Using low temperature power dependent PL, temperature dependent PL, and Raman scattering experiment to acquire optical properties of material; And using Time resolved PL to acquire the minority carrier lifetime of HBT base structure.
In EXAFS experiment, we found that if our samples are thin or have low mole fraction of the element we want to detect, it would be difficult to obtain a reasonable set of data. So we test different regions of data selections, conclude that we can only change one parameter at a time, and do data selections repeated in both R-space and K-space. In the end, judge the quality of data by R-factor.
In Photoluminescence experiment, we measure the temperature dependent PL of GaAs base HBT structure, by doing linear extrapolation of low energy shoulder of spectrum, we can obtain emission energy for each temperature we measured, then using Varshni equation to fit data point in order to get room temperature emission energy, compared it with BGN model to modify this process is adoptable. In the end, using this process to obtain the room temperature emission energy GaAsPSb base HBT structure, which is 1.247eV.
In TRPL experiment, using the room temperature emission energy obtained from PL to measure minority carrier lifetime of pre-selected wavelength, the minority carrier lifetime of GaAsPSb base is 16.6ps.
In Raman scattering experiment, we discuss the differences between one layer structure and multilayer structure of the influence from excitation power. The result shows there might exist electric field in multilayer structure, causing photo excited electron-hole pair dissociation, and screening a partial of electric field, leading to the different growth rate of each peak. Besides, we use alloy potential and anharmonicity effect to describe asymmetry and peak shift.
Subjects
Photoluminescence
Time-Resolved Photoluminescence
Raman Scattering.
Type
thesis
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