通過掃描式穿隧顯微鏡比較機械剝離法前後二硫化錸的電子特性

Compare the Electron properties of ReS2 Surface before and after Mechanical Exfoliation by Scanning Tunneling Microscope

盧奕宏(Lu Yi-Hung)

指導教授 ： 傅祖怡

國立臺灣師範大學/理學院/物理學系/碩士(2017年)

https://doi.org/10.6345/NTNU202202048

摘要

二硫化錸層狀半導體屬於過渡金屬二硫族化物(TMD)的材料。隨著二維材料的發展，這種 層狀半導體在表面上的電性是最近非常熱門的課題。藉由STM/STS的量測，我們更加認識二硫化錸在表面上的行為。
比較機械剝離法(簡稱Fresh)前後的二硫化錸的表面。首先進行Non-Fresh的直接量測，形貌上面本來有許多亮點與暗點，但是經過Fresh表面之後的ReS2亮點卻消失。藉由形貌去推斷ReS2上的亮點形成可能來自於ReS2吸附雜質或是表面突起，ReS2的暗點推測是結構上的缺陷或是表面凹陷。
此外，實驗顯示電性上ReS2是n-type的半導體，而且發現在Fresh過後的電性比Non-Fresh更有更多的電子載子的狀況。對比上述Non-Fresh所擁有的形貌特徵，吸附雜質並不會貢獻出載子消耗的變化，經由曝大氣之後的ReS2造成表面有局部的漣漪凸起會讓載子濃度降低。
將Fresh過後在大氣下曝氣兩個月的樣品再次進行量測，形貌和電子特性大致上還原成Non-Fresh的情況，說明經Fresh二硫化錸表面的特性受大氣的影響而且是會重複且發生。

關鍵字

掃描式穿隧電子顯微鏡 ； 過渡金屬二硫族化物 ； 二硫化錸 ； 機械剝離法

並列摘要

Layer semiconductor rhenium disulfide(ReS2) belongs to the material of transition metal dithiocarbamate (TMD). With the development of two-dimensional materials, the electrical properties of such a layered semiconductor on the surfaces are extremely popular recently. With measurement of scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), we can know more the behaviors of rhenium disulfide on the surfaces.
The surfaces of ReS2 were compared before and after mechanical exfoliation (Fresh). At first, the Non-Fresh ReS2 was measured, the surfaces topography appears many light points and dark points. After Fresh, the light point on the ReS2 surfaces disappears. Based on the topography information of ReS2, the light points may be formed from the adsorption impurities or protruding surfaces. Dark points may be formed from the vacancy or depression surfaces.
Besides, the electron properties of ReS2 is a n-type semiconductor. The Fresh ReS2 has more electron carriers than Non-Fresh ReS2. Based on the results of topography and STS, adsorption impurities on surface of Non-Fresh ReS2 don’t contribute the electron depletion. Electron carrier depletion mainly results from the local protrusion which occurs after exposure to atmosphere.

並列關鍵字

STM ； TMD ； ReS2 ； Mechanical Exfoliation

參考文獻

[1] K.S. Novoselov, A.K. Geim, S.V. Morozov, D. Jiang, Y. Zhang, S.V. Dubonos, I.V. Grigorieva, A.A. Firsov, Electric Field Effect in Atomically Thin Carbon Films, Science, 306 (2004) 666-669.

[2] M. Xu, T. Liang, M. Shi, H. Chen, Graphene-like two-dimensional materials, Chem Rev, 113 (2013) 3766-3798.

[3] K. Novoselov, D. Jiang, F. Schedin, T. Booth, V. Khotkevich, S. Morozov, A. Geim, Two-dimensional atomic crystals, Proceedings of the National Academy of Sciences of the United States of America, 102 (2005) 10451-10453.

[4] W. Feng, W. Zhenxing, W. Qisheng, W. Fengmei, Y. Lei, X. Kai, H. Yun, H. Jun, Synthesis, properties and applications of 2D non-graphene materials, Nanotechnology, 26 (2015) 292001.

[5] K.F. Mak, C. Lee, J. Hone, J. Shan, T.F. Heinz, Atomically Thin MoS2: A New Direct-Gap Semiconductor, Physical Review Letters, 105 (2010) 136805.