Studies of Electro-Optic Properties of Semiconductors by Chemical Etched and Fast Fourier Transform

• Main Authors: Kun-Ming Hung, 洪崑明
• Other Authors: Jenn-Shyong Hwang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/88726892320610950372

碩士 === 國立成功大學 === 物理學系 === 89 === The first part of this study used photoreflectance (PR) spectra to investigate the build-in electric fields and interband transitions of a series of lattice mismatched GaAs/InxGa1-xAs heterostructures with a Si d-doping and a single quantum well. PR spectra were taken after step-by-step etching. From the analysis of the PR spectra taken at various stages, it is concluded that there is a large electric field between the sample surface and the d-doping and a small electric field between the d-doping and the quantum well. Interband transitions within the quantum well were observed when the surface layer and d-doping have been removed. Energies of confined levels as well as energies of interband transitions were theoretically calculated by model solid theory. The transition energies measured from the PR spectra agree well with those theoretically calculated from the confined levels in the quantum well. Results obtained above allow the band diagram of the heterostructure to be defined. The fast Fourier transformation (FFT) was, for the first time, applied to the PR spectra of a semiconductor other than material like GaAs. The FFT of the PR spectra of InAlAs appears as a broad peak, produced by the overlap of the two peaks corresponding to light- and heavy-hole transitions. Deconvolution process was applied to resolve these two peaks. The peak positions are related to the electric field in the sample, band gaps and reduced masses of the heavy- and light-holes, respectively. Assuming that heavy- and light-hole experience the same electric field, the band gaps of heavy- and light-holes change until the electric fields determined from the two peak positions are identical. The band gaps are associated with the splitting of heavy- and light-hole energy levels in the valance band. According to deformation potential theory and model-solid theory, valence band splitting can be theoretically estimated from the strain induce by electric field. The results obtained agree closely with those obtained from FFT analysis. 第二章 光調制光譜學理論..........................................................6 2-1 低電場調制......................................................................7 2-2 Franz-Keldysh振盪...........................................................8 2-3 光調制光譜學的機制.....................................................11 2-4 譜線擬合.........................................................................12 第三章 實驗裝置.........................................................................14 第四章 含d摻雜及量子井之GaAs能譜研究..............................18 4-1 樣品和實驗條件.............................................................19 4-2 實驗結果與討論.............................................................21 4-2-1 譜線分析.........................................................................21 4-2-2 能階躍遷能量計算.........................................................37 4-3 結論.................................................................................43 第五章 以傅利葉分析方法研究GaAs與InAlAs SIN+結構 之光調制光譜..................................................................50 5-1 樣品和實驗條件...............................................................51 5-2 實驗結果與討論...............................................................53 5-2-1 譜線分析...........................................................................53 5-2-2 Heavy-hole與Light-hole能階分裂之分析........................59 5-3 結論...................................................................................68 第六章 總結...................................................................................70 參考文獻 …………………………………………………………...……..72