臺灣博碩士論文加值系統

我們利用SdH量測（Shubnikov-de Haas measurement）研究GaAs/Al0.3Ga0.7As雙量子井（double quantum wells）內的二維電子系統；其中，雙量子井裡簡并的次能帶（degenerate subbands）變成兩個z方向上的波函數（一為對稱：symmetric，一為反對稱：anti- symmetric），我們觀察到了由第二個有反對稱波函數之次能帶所產生的SdH oscillation，發現第二個次能帶的有效質量（effective mass）與磁場（0.680T→1.964T）呈線性關係；而若雙量子井壁有相等厚度，其有效質量增加的幅度會比不相等的大，電子與電子間的交互作用便是質量增加的原因。

The two-dimensional electron system in strongly coupled GaAs/Al0.3Ga0.7As double quantum wells has been studied by Shubnikov-de Haas（SdH）measurements. The degenerate subbands of the double quantum wells are lift into two subbands with a symmetric or anti- symmetric z-direction wave function. We observed that the SdH oscillation due to the second subband of anti-symmetric wave function. The effective mass of the second subband is linearly dependent on the magnetic field range from 0.680 T to 1.964 T. The mass enhancement for the double-quantum-well with an equal well thickness is greater than that with an unequal one. This mass enhancement is attributed to the electron-electron interaction.

第一章 簡介
1-1 前言………………………………………………………………1
1-2 實驗的基本條件…………………………………………………3
1-3 量子井二維電子氣的特性………………………………………4
第二章 理論部分
2-1 Landau level 和spin splitting Landau level……………6
2-2 Shubnikov-de Haas 效應 ………………………………………7
第三章 實驗儀器設備
3-1 儀器設備簡介 ……………………………………………………9
3-2 管路裝置…………………………………………………………10
3-3 低溫恆溫器（cryostat）…………………………………………11
第四章 實驗步驟
4-1 sample的處理……………………………………………………18
4-2 降溫 ………………………………………………………………21
第五章 實驗結果與討論
5-1 Samples的結構 …………………………………………………30
5-2 結果與討論 ………………………………………………………33
Reference ……………………………………………………………57

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