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。

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.

[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.
[6] S.-L. Li, K. Tsukagoshi, E. Orgiu, P. Samorì, Charge transport and mobility engineering in two-dimensional transition metal chalcogenide semiconductors, Chemical Society Reviews, 45 (2016) 118-151.
[7] Q.H. Wang, K. Kalantar-Zadeh, A. Kis, J.N. Coleman, M.S. Strano, Electronics and optoelectronics of two-dimensional transition metal dichalcogenides, Nat Nanotechnol, 7 (2012) 699-712.
[8] A.K. Geim, I.V. Grigorieva, Van der Waals heterostructures, Nature, 499 (2013) 419-425.
[9] A. Kuc, N. Zibouche, T. Heine, Influence of quantum confinement on the electronic structure of the transition metal sulfide TS2, Physical Review B, 83 (2011) 245213.
[10] J.V. Marzik, R. Kershaw, K. Dwight, A. Wold, Photoelectronic properties of ReS2 and ReSe2 single crystals, Journal of Solid State Chemistry, 51 (1984) 170-175.
[11] K. Friemelt, S. Akari, M.C. Lux-Steiner, T. Schill, E. Bucher, K. Dransfeld, Scanning tunneling microscopy with atomic resolution on ReS2 single crystals grown by vapor phase transport, Annalen der Physik, 504 (1992) 248-253.
[12] S. Akari, K. Friemelt, K. Glöckler, M.C. Lux-Steiner, E. Bucher, K. Dransfeld, Photo-induced tunneling spectroscopy of ReS2: Dramatic increase of the quantum efficiency by chemical treatment, Applied Physics A, 57 (1993) 221-223.
[13] S.P. Kelty, A.F. Ruppert, R.R. Chianelli, J. Ren, M.H. Whangbo, Scanning Probe Microscopy Study of Layered Dichalcogenide ReS2, Journal of the American Chemical Society, 116 (1994) 7857-7863.
[14] H.H. Murray, S.P. Kelty, R.R. Chianelli, C.S. Day, Structure of Rhenium Disulfide, Inorganic Chemistry, 33 (1994) 4418-4420.
[15] C.M. Fang, G.A. Wiegers, C. Haas, R.A.d. Groot, Electronic structures of ReS2, ReSe2, and TcS2 in the real and the hypothetical undistorted structures, Journal of Physics: Condensed Matter, 9 (1997) 4411.
[16] S. Tongay, H. Sahin, C. Ko, A. Luce, W. Fan, K. Liu, J. Zhou, Y.-S. Huang, C.-H. Ho, J. Yan, D.F. Ogletree, S. Aloni, J. Ji, S. Li, J. Li, F.M. Peeters, J. Wu, Monolayer behaviour in bulk ReS2 due to electronic and vibrational decoupling, Nature Communications, 5 (2014) 3252.
[17] K.K. Tiong, C.H. Ho, Y.S. Huang, The electrical transport properties of ReS2 and ReSe2 layered crystals, Solid State Communications, 111 (1999) 635-640.
[18] C.M. Fang, G.A. Wiegers, C. Haas, R.A.d. Groot, Electronic structures of , and in the real and the hypothetical undistorted structures, Journal of Physics: Condensed Matter, 9 (1997) 4411-4424.
[19] 台. 陳瑞山, unpulish, discuss in Private meeting, DOI (2016).
[20] H.-P. Komsa, A.V. Krasheninnikov, Native defects in bulk and monolayer ${\mathrm{MoS}}_{2}$ from first principles, Physical Review B, 91 (2015) 125304.
[21] R. Addou, L. Colombo, R.M. Wallace, Surface Defects on Natural MoS2, ACS Applied Materials & Interfaces, 7 (2015) 11921-11929.
[22] H. Liu, H. Zheng, F. Yang, L. Jiao, J. Chen, W. Ho, C. Gao, J. Jia, M. Xie, Line and Point Defects in MoSe2 Bilayer Studied by Scanning Tunneling Microscopy and Spectroscopy, ACS nano, 9 (2015) 6619-6625.
[23] A. Inoue, T. Komori, K.-i. Shudo, Atomic-scale structures and electronic states of defects on Ar+-ion irradiated MoS 2, Journal of Electron Spectroscopy and Related Phenomena, 189 (2013) 11-18.
[24] I. Mahboob, T.D. Veal, C.F. McConville, H. Lu, W.J. Schaff, Intrinsic Electron Accumulation at Clean InN Surfaces, Physical Review Letters, 92 (2004) 036804.
[25] P.D.C. King, T.D. Veal, F. Fuchs, C.Y. Wang, D.J. Payne, A. Bourlange, H. Zhang, G.R. Bell, V. Cimalla, O. Ambacher, R.G. Egdell, F. Bechstedt, C.F. McConville, Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedralIn2O3, Physical Review B, 79 (2009).
[26] N. Ishida, K. Sueoka, R.M. Feenstra, Influence of surface states on tunneling spectra of n-type GaAs (110) surfaces, Physical Review B, 80 (2009) 075320.
[27] K. Xu, H.-X. Deng, Z. Wang, Y. Huang, F. Wang, S.-S. Li, J.-W. Luo, J. He, Sulfur vacancy activated field effect transistors based on ReS2 nanosheets, Nanoscale, 7 (2015) 15757-15762.
[28] J. Shim, A. Oh, D.H. Kang, S. Oh, S.K. Jang, J. Jeon, M.H. Jeon, M. Kim, C. Choi, J. Lee, S. Lee, G.Y. Yeom, Y.J. Song, J.H. Park, High-Performance 2D Rhenium Disulfide (ReS2 ) Transistors and Photodetectors by Oxygen Plasma Treatment, Adv Mater, 28 (2016) 6985-6992.
[29] A.N. Enyashin, I. Popov, G. Seifert, Stability and electronic properties of rhenium sulfide nanotubes, physica status solidi (b), 246 (2009) 114-118.
[30] C.H. Ho, Y.S. Huang, J.L. Chen, T.E. Dann, K.K. Tiong, Electronic structure of ReS2 and ReSe2 from first-principles calculations, photoelectron spectroscopy, and electrolyte electroreflectance, Physical Review B, 60 (1999) 15766-15771.
[31] X. Zhang, Q. Li, Electronic and magnetic properties of nonmetal atoms adsorbed ReS2 monolayers, Journal of Applied Physics, 118 (2015) 064306.
[32] D. Çakır, H. Sahin, F.M. Peeters, Doping of rhenium disulfide monolayers: a systematic first principles study, Phys Chem Chem Phys, 16 (2014) 16771-16779.
[33] Z.G. Yu, Y. Cai, Y.-W. Zhang, Robust Direct Bandgap Characteristics of One- and Two-Dimensional ReS(2), Scientific Reports, 5 (2015) 13783.
[34] Z. Xiao-Ou, L. Qing-Fang, Strain-induced magnetism in ReS 2 monolayer with defects, Chinese Physics B, 25 (2016) 117103.
[35] 研之有物-中央研究院, http://research.sinica.edu.tw/chuang-tien-ming-stm/chuang-tien-ming-stm-20170602-01/, DOI.
[36] 維基百科, https://zh.wikipedia.org/wiki/%E9%87%8F%E5%AD%90%E7%A9%BF%E9%9A%A7%E6%95%88%E6%87%89, DOI (2017).
[37] G.J. de Raad, D.M. Bruls, P.M. Koenraad, J.H. Wolter, Interplay between tip-induced band bending and voltage-dependent surface corrugation on GaAs(110) surfaces, Physical Review B, 66 (2002).
[38] R. Dombrowski, C. Steinebach, C. Wittneven, M. Morgenstern, R. Wiesendanger, Tip-induced band bending by scanning tunneling spectroscopy of the states of the tip-induced quantum dot on InAs(110), Physical Review B, 59 (1999) 8043-8048.
[39] 科學online. 掃描式穿隧電子顯微鏡, http://highscope.ch.ntu.edu.tw/wordpress/?p=22563, DOI.
[40] Onmicron, The VT SPM User's Guide, 2000.
[41] 黃榮俊, 自發性奈米結構之掃描穿隧電子顯微鏡觀測, 成大研發快訊, 4-08 (2008).
[42] 國科會精儀中心, 真空技術與應用, DOI.
[43] 台灣word. 真空計, http://www.twword.com/wiki/%E7%9C%9F%E7%A9%BA%E8%A8%88, DOI.
[44] 中國科技大學. 张淑贞, http://www.bb.ustc.edu.cn/jpkc/guojia/dxwlsy/kj/part1/4-4.html, DOI (2003).
[45] X. Liu, I. Balla, H. Bergeron, M.C. Hersam, Point Defects and Grain Boundaries in Rotationally Commensurate MoS2on Epitaxial Graphene, The Journal of Physical Chemistry C, 120 (2016) 20798-20805.
[46] K. Xu, P. Cao, J.R. Heath, Scanning Tunneling Microscopy Characterization of the Electrical Properties of Wrinkles in Exfoliated Graphene Monolayers, Nano Letters, 9 (2009) 4446-4451.