利用蒸鍍沉積外來原子調控準獨立鍺烯的形成

Triggering the formation of quasi-freestanding germanene by foreign-atoms deposition

陳亭宇(Ting-Yu Chen)

指導教授 ： 唐述中

國立清華大學/理學院/物理學系/碩士(2018年)

摘要

石墨烯的發現激起大家對於相關二維材料研究的極大興趣，包含最直覺的與碳元素同為第四族元素的鍺所構成的鍺烯。本論文的基礎建立於鍺烯在銀(111)上的兩個不同相，其一為條紋相(striped phase)，它結構的其中一個方向被拉長以與銀基底的晶格長度相稱；另一個相為準獨立相(quasi-freestanding phase)，它與理論上的獨立鍺烯相近，但與銀基底晶格長度有著較大的差異，因此較為無序。我們以角解析光電子能譜、低能量電子繞射儀和掃描穿隧式顯微術來研究一個有趣的想法：利用蒸鍍沉積外來原子調控準獨立鍺烯的形成。適當選擇的外來原子如同界面活性劑，若它能不破壞鍺烯的結構，反而促使條紋相鍺烯的張力被釋放，形成準獨立鍺烯，並且藉由夾擠作用使準獨立鍺烯更為穩定有序。我們以鉛做為外來原子，於鍺烯在銀(111)的樣品上進行一系列的實驗，其結果啟發也驗證了我們的想法，這樣的機制也可望有更廣泛的用途。

關鍵字

鍺烯 ； 銀(111)

並列摘要

The discovery of graphene has spurred great interest in the exploration of novel 2D materials, including the intuitive graphene’s siblings, germanene, made of group IV element Ge. This work is the further study of the single-layer dual germanene phases on Ag(111). One such phase, striped phase (SP), is tensile strained and partially commensurate with the substrate. The other, a quasi- freestanding phase (QP), which is very close to the freestanding germanene predicted by the first-principles calculation, fully relaxes the tensile strain at the cost of more lattice mismatch. The interesting idea of this study is triggering the formation of QF germanene from SP germanene by foreign-atom deposition. The experimental techniques such as low energy electron diffraction (LEED), angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM) were employed in the research of this thesis. Foreign atoms, as surfactants, play a role in relaxing the tensile strain of SP germanene, and stabilizing the QP germanene by squeezing effect. We have done a series of experiments using Pb as the foreign atom to verify not just the idea but the very interesting mechanism.

並列關鍵字

germanene ； Ag(111)

參考文獻

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