我們以第一近鄰鍵結軌域模型研究無共用原子之InAs-GaSb超晶格能帶結構，並考慮了不對稱的交界面所造成的影響。這個模型能相當正確的複製塊材在靠近布里淵區中央的能帶結構。我們發現首次被包含於鍵結軌域模型的界面不對稱性會導致能階的分裂；我們也發現，當超晶格週期變大時會產生負的非直接能隙現象，這是由於界面的不對稱性和GaSb材料重電洞帶之各向異性所造成。這也顯示出當週期d達到臨界厚度dC時，半導體－半金屬的相轉變確實存在於此InAs-GaSb超晶格中。我們計算出的臨界厚度大約是150Å。

We study the electronic band structure of no-common-atom InAs-GaSb superlattice within a nearest-neighbor bond-orbital model. The effect of interfacial asymmetry is also taken into account. This model can reproduce fairly accurate bulk band structures near the center of the Brillouin zone. We find that interfacial asymmetry, which is first included in bond-orbital model, can yield spin splitting. We also find that a negative indirect band gap appears for long period superlattice, due to interfacial asymmetry and band anisotropy of the heavy hole band in GaSb material. This indicates that the semiconductor-semimetal transition, which occurs when the period d reach a critical value dC, does exist in InAs-GaSb superlattice. In our calculation, the critical period dC is about 150 Å.

第一章 前言 ……………………………………………1
第二章 理論 ……………………………………………6
2.1 鍵結軌域模型………………………………………6
2.2 參數的求法………………………………………..13
2.3 超晶格的能帶計算………………………………..14
第三章 結果與討論 …………………………………...17
3.1 塊材能帶…………………………………………..17
3.2 超晶格……………………………………………..20
第四章 總結 …………………………………………...38
附錄一 ………………………………………………………..40
附錄二 ………………………………………………………..45
參考文獻 ……………………………………………………..49

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