• 作者： 吳啟宗
• 作者服務機構： 國立交通大學電子工程系暨電子研究所
• 中文摘要： 在量子化磁場且極低溫度下，利用量子力學方法研究簡併半導體如N型砷化鎵內所產生自由載子吸收之現象。假設半導體內電子之能帶結構為非拋物線性，而其主要散射機構為由形變位能耦合產生之聲振子散射。若輻射波沿磁場方向產生極化，則由於半導體內之輻射場和聲子之交互作用，使吸收係數成為複數值。結果顯示簡併N型砷化鎵內之吸收係數的實數和虛數部份，在較低磁場下因磁場變化而產生巨大振動，且可觀測到不連續點。若磁場增至某值時，其振動之振幅減少至相當小值。若磁場再增加，吸收係數之實數部份急速下降，然後緩慢且單調之增加；而虛數部份將於某磁場下急速地消失。然而，若電子密度增加，此種因磁場而產生急速變化將消失。且在高磁場下，吸收係數之實數與虛數部份，仍然依磁場變化而振動。
• 英文摘要： Free-carrier absorption in degenerate semiconductors such as n-type GaAs has been investigatedquantum mechanically at quantizing magnetic fields in a very low temperature limit. It is assumed that theenergy band structure of electrons in semiconductors is nonparabolic and that the dominant scatteringmechanism for electrons is the acoustic phonon scattering via deformation potential coupling. When theradiation is polarized parallel to a do magnetic field, the absorption coefficient appears to be of a complexvalue due to the radiation field and the phonon field in semiconductors. Results show that both real andimaginary parts of the absorption coefficient in degenerate n-type GaAs oscillate quite considerably in thelow-field region and that some discontinuous points can be observed. When the magnetic field increasesup to a certain value, the amplitude of oscillations will be reduced to a quite small value. Whenthe magnetic field increases further, the real part of the absorption coefficient will drop abruptly and thenincrease slowly and monotonically with the magnetic field, while the imaginary part of the absorptioncoefficient will vanish rapidly with the magnetic field. However, if the electron density increases, thisabrupt change with the magnetic field will disappear. Moreover, both real and imaginary parts of theabsorption coefficient still oscillate with the magnetic field in the high-field region.
• 中文關鍵字： free-carrier absorption; degenerate semiconductors; nonparabolic; acoustic phonon scattering; deformation-potential coupling; radiation field
• 英文關鍵字： --