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

【1】郭桂冠, ”Magneto-transport studies of δ-doped III-V
semiconductor quantum wells” (1996).
【2】黃雲龍, ”Transport studies in AlSb/InAs quantum well at
low temperature and high magnetic field” (1999).
【3】Ikai Lo, J. K. Tsai, P. C. Ho, W. J. Yao, C. H. Chang, and
Li-Wei Tu, “Second subband population of two-dimensional
electron gas in strongly coupled GaAs/Al0.3Ga0.7As double
quantum wells” (2002).
【4】Q. X. Zhao, S. Wongmanerod, M. Willander, P. O. Holtz, E.
Selvig, and B. O. Fimland, Phys. Rev. B 62, 10984 (2000)
【5】K. K. Choi, D. C. Tsui, and S. C. Palmateer, Phys. Rev. B 33,
8216 (1986).
【6】M. Dobers, K. von Klitzing, and G. Weimann, Phys. Rev. B
38, 5453 (1988).
【7】D. Stein, K. von Klitzing, and G. Weimann, Phys. Rev. Lett.
51, 130 (1983).
【8】H. Wang, M. Jiang, R. Merlin, and D. G. Steel, Phys. Rev.
Lett. 69, 804 (1992).