角解析光電子能譜研究銦薄膜在平坦以及斜切2.7°的鍺(100)上之電子結構以及費米面

Studies of Band structures and Fermi Surfaces of In/Ge(100) and In/Ge(100)-[011]2.7° by angle-resolved photoemission spectroscopy

翁慈敏(Tzu-Min Weng)

指導教授 ： 唐述中

國立清華大學/理學院/物理學系/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00398

摘要

我們利用角解析光電子能譜（ARPES）成功的測量了銦薄膜(〜0.4 ML)在平坦鍺(100)面和在鍺(100)鄰位面(沿[011]方向呈2.7°角)的2×2結構中的電子結構。我們發現在費米能量附近形成了表面態，並認為在兩個系統中的表面態可以歸因於銦價電子和鍺懸鍵之間的交互作用。我們利用第一原理計算來模擬In/Ge(100)-(2×2)結構，並研究了兩種不同的模型：(i) 銦二聚體平行於鍺二聚體的模型，以及 (ii) 銦二聚體正交於鍺二聚體的模型。其中，以銦二聚體平行於鍺二聚體的模型計算結果是比較符合我們的ARPES實驗結果。在二維等能量面中，我們發現有趣的情形：費米面拓撲結構的電子表面態，似乎因為銦薄膜在平坦鍺(100)面和在鍺(100)鄰位面上而有所不同；而比較In/Ge(100)和In/Ge(100)- [011] 2.7°的能帶寬、kF和表面態的電子密度後也非常地符合這一發現。

關鍵字

鍺 ； 銦 ； 費米面 ； 角解析電子能譜 ； 能帶結構 ； 低能量電子繞射儀 ； 鄰位面 ； 國家同步輻射中心

並列摘要

By using angle-resolved photoemission spectroscopy (ARPES), we measured successfully the electronic structure of low coverage (2×2) phases of indium thin films (~0.4ML) on flat Ge(100) surface and vicinal Ge(100) surface. We found several surface states crossing the Fermi level. We think in both systems surface states can be attributed to the hybridization between indium valence electrons and Germanium dangling bonds. The electronic structures of In/Ge(100)-(2×2) was simulated by first-principles calculation. Two different models have been investigated: the indium ad-dimers (i) parallel and (ii) orthogonal to the substrate Ge dimmers. To compare with measured results, the calculation based on In ad-dimers parallel to the Ge dimmers model is consistent with our ARPES result. By inspecting the 2D constant energy contours at Fermi level, we found interesting Fermi surface topology, the electron-like surface state bands seems different between indium deposited flat Ge(100) surface and indium deposited vicinal Ge(100) surface. The estimation of band width, kF, and electron density of surface states in In/Ge(100) and in In/Ge(100)- [011] 2.7° also agree with this discovery very well.

並列關鍵字

Germanium ； Indium ； Fermi surface ； angle-resolved photoemission spectroscopy ； band structure ； LEED ； vicinal surface ； NSRRC

參考文獻

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