半導體兆赫波源及電流震盪器之研究

Abstract

在本論文中我們嘗試兩種實現兆赫波源的方式，從可見光頻率的方向，利用矽鍺量子井異質接面結構產生的應力變形效應所造成的價帶間副能帶間粒子數反轉而達到兆赫波，另外我們利用將片狀摻雜從量子井的中央移到量子井的邊緣來大幅降低載子的解離能進而提高了電流的增益。微波頻率的方向，利用砷化鋁鎵/砷化鎵/鋁化鎵/砷化鎵之量子井結構因外加電場而造成的甘恩效應來產生兆赫波段的震盪波，雖目前得到的頻率僅在數百MHz的範圍，但因為我們採用的通道長度較長(約5μm)。除了震盪電流之外，我們也發現許多非常有趣的物理現象，諸如磁滯的現象，記憶的現象，對光線十分的敏感等。

In this thesis , we try to realize the terahertz sources in two different directions. From the visible light frequency , the intracenter population inversion between the valence subbands due to the strain of Si/SiGe single quantum well heterostructure will lead to get terahertz emission. Furthermore , we suggest to use the δ-doping into the edge of QW instead of doping into the center of QW that will decrease the binding energy from 31meV to 15meV and increase the current gain.From the microwave side , we try to get THz oscillation by the force of the Gunn effect due to exert external electric field to AlGaAs /GaAs/AlAs/AlGaAs heterostructure. Although the oscillation frequency which we observed is still in the few hundred MHz range , we use large length between source and drain(about 5μm). Besides the current oscillation , we also discovered other interested physics like magnetic hysterisis , good photo detector , and memory effect.