利用掃描穿隧式電子顯微鏡解析鐵顆粒成長於碘碲化鉍

Fe Grain Grown on BiTeI Resolved by Scanning Tunneling Microscopy

謝偉安(Wei-An Hsieh)

指導教授 ： 林敏聰

國立臺灣大學/理學院/物理研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10299

摘要

Rashba 半導體－碘碲化鉍（BiTeI）其能帶結構－不論是塊材能帶還是表面能帶皆具有極大的Rashba 自旋分裂。不同自旋方向的電子擁有獨立能帶的性質對於未來自旋電子儀器設計有相當幫助，一個極具應用潛力的新興材料。為了將來科技應用，我們選用廣泛使用的磁性材料－鐵，探索鐵在碘碲化鉍的成長機制。
在本篇論文中，首先探討純的碘碲化鉍表面性質，我們將塊材-碘碲化鉍樣品切割，利用掃描穿隧式電子顯微鏡（Scanning Tunneling Microscopy）觀察切面，探索其表面特性與缺陷，並且使用掃描穿隧式電子能譜（Scanning Tunneling Spectroscopy）研究其電子能帶結構，確認其與文獻相合之碲和碘的獨特表面。接著我們將鐵原子蒸鍍於表面，掃描穿隧式電子顯微鏡顯示鐵在碲和碘表面有不同的成長機制，以及用掃描穿隧式電子光譜發現兩種表面都有能帶位移的現象，我們認為其由來為與鐵混成後之電性結構改變。

關鍵字

Rashba 效應 ； 碘碲化鉍 ； 能帶位移 ； 鐵 ； 成長機制 ； 掃描穿隧式電子顯微鏡

並列摘要

BiTeI, a Rashba semiconductor, contains signi cantly strong Rashba spin-splitting not only in the bulk energy band but also in the surface one. The fact that electrons with opposite spin direction have independent band structure is promising and helpful for spintronic device design in the future. For practical concern in device fabrication, we choose a widely-used magnetic material, iron, to explore its growth on the surface of BiTel.
In this thesis, we investigate the surface properties of pristine BiTeI rst. We cleaved bulk BiTeI, and then used scanning tunneling microscopy (STM) to observe the cross section for studying its surface properties and defects. We also used scanning tunneling spectroscopy (STS) to probe its electronic band structure. The results con rmed that BiTeI exhibits two distinct surface terminations, Te-termination and I-termination, and were in agreement with the published literatures. Then we present iron adatoms grown on BiTeI by thermal evaporation. STM topographies showed that growth modes of two terminations were di erent, and STS data showed band shifts on both terminations. We think that the band shift from electronic properties changed after hybridization with iron atoms.

並列關鍵字

Rashba effect ； BiTeI ； band shift ； iron ； growth mode ； scanning tunneling microscopy

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