自由立態(Free Standing) Single Bi-bilayer 被預測二為拓樸絕緣體，並於Single Bi-bilayer/Bi2Te3(0001) 系統中獲得實驗證實，導致近年來成長高品質Single Bi-bilayer 成為熱門課題。目前，高品質的 Single Bi-bilayer 可透過分子束磊晶(MBE)於 Bi2Se3(0001) 晶面上成長 Bi 薄膜達成，且其表面形貌、能帶結構量測亦已得到，而氫原子侵蝕 Bi2Se3(0001) 晶面所取得的高品質的 Single Bi-bilayer 覆蓋率試樣，經預測具相同電子能帶結構，只是目前尚未有量測結果。
氘原子侵蝕 Bi2Se3(0001) 晶面的試樣表面結構探究藉掃描穿隧電子顯微術(STM)進行，試樣表面成分分析則利用X 射線光電子能譜術(XPS)與真空紫外光光電子能譜術(UPS)，其中， Bi 原子 5d 核層電子訊號的量測，前後量者入射光能量分別為 380 eV 與 55 eV 。透過以上研究結果，們獲得以下推論 : 定義一層 Bi-bilayer 為 BL ，氘原子侵蝕 Bi2Se3(0001) 晶面後，試樣表面近 1.5 層 Quintuple layer (QL) 被破壞且 Bi-bilayer 飽和覆蓋量為 1.30±0.02 BL 。除此之外，上述的 X 射線光電子能譜術(XPS)與真空紫外光光電子能譜術(UPS)成果，本研究中 Bi 薄膜在 Bi2Se3(0001) 晶面上的蒸鍍厚度亦以之為參考。
實驗試樣的電子能帶結構以角解析光電子能譜(ARPES)量測，其中，試樣費米能級(E_F)透過 Ag(111) 單晶校訂。由於 Single Bi-bilayer/Bi2Se3(0001) 系統不論是以氫(氘)原子侵蝕製程還是以分子束磊晶(MBE)製程，狄拉克點 D_B 、 D_S 之間的束縛能差額 〖∆E〗_B≅0.3 Ev ，上(SSu)、下(SSd)自旋電子在 E_B=0.000 eV 或 E_B=0.540 eV 時被允許存在的動量位置點差額 〖∆k〗_(||)≅0.235 eV 或 〖∆k〗_(||)≅0.215 eV ，所以我們可歸納出以下論點 : 兩種製程方式成長出來的Single Bi-bilayer/Bi2Se3(0001) 電子能帶結構基本上無太大差異。
故透過本研究，得到以下兩結論，第一，氘原子侵蝕 Bi2Se3(0001) 晶面後，試樣表面近 1.5 層 Quintuple layer (QL) 被破壞且 Bi-bilayer 飽和覆蓋量為 1.30±0.02 BL 。第二，氫(氘)原子侵蝕 Bi2Se3(0001) 晶面取得的高品質 Single Bi-bilayer 覆蓋試樣，其表面電子能帶結構與分子束磊晶(MBE)於 Bi2Se3(0001) 晶面成長的 Single Bi-bilayer 相同。

Free standing Bi-bilayer has been predicted as a two dimensional topological insulator. Therefore, how to prepare a high quality Bi-bilayer thin film becomes a hot research topic. The electronic band structure of the MBE single Bi-bilayer on the Bi2Se3(0001) surface had been revealed by Lin Miao et al. Recently, Roozbeh Shokri et al. suggested that the samples with high single Bi-bilayer coverage can be produced by the hydrogen radical etching process and that the band structure of H-etching Bi-bilayer/Bi2Se3(0001) system is similar to that grown by MBE. However, the band structure of the H-etching Bi-bilayer/Bi2Se3(0001) system had not been measured before.
In this work, we will measure its band structure by angle resolved photoemission.We have first prepared the Bi-bilayer by H-etching of the cleaved Bi2Se3(0001) surface. Then we studied its surface morphology and the atomic structure by scan tunneling microscopy (STM) and have analyzed stoichemistry on the surface by means of the ultraviolet photoemission spectroscopy (UPS) and the X-ray photoemission spectroscopy (XPS) with photo energy 55 eV and 380 eV respectively. By combining the results from STM, XPS and UPSs, we can conclude that, the Bi-bilayer coverage on the deuterium radical etching Bi2Se3(0001) is 1.30±0.02 Bi-bilayer when the effect of deuterium radical etching was saturated at the expense of about 1.5 Quintuple layer (QL) The coverage of single Bi-bilayer is about 70 % on the top of sample. Our results from STM, XPS and UPS provide not only a good evidence for our first conclusion but also a reference for the Bi deposition rate estimation for the ARPES experiment.
In our ARPES experiment, the Fermi-level E_F was first calibrated by Ag(111) crystal and the thickness of Bi film was estimate by STM, UPS and XPS. The ARPES results show that, no matter which well performance single Bi-bilayer growth mode we chosed, by low temperature (200 K) MBE process or room temperature hydrogen radical-etching process, the electronic band structure is the same ”. The reasons were two folds, first, the binding energy difference 〖∆E〗_B between Dirac point D_B and D_S are 0.3 eV. Second, the momentum difference 〖∆k〗_(||) between spin up state electron and spin down state electrons at E_B=0.000 eV and E_B=0.540 eV are 〖∆k〗_(||)≅0.235 Å^(-1) 〖∆k〗_(||)≅0.215 Å^(-1).
In conclusion, we can get two points. First, “ the Bi-bilayer coverage on the deuterium radical etching Bi2Se3(0001) will be 1.30±0.02 Bi-bilayer when the effect of deuterium radical etching was saturate ”. Second, “ no matter which well performance single Bi-bilayer growth mode we chosed, by low temperature (200 K) MBE process or room temperature hydrogen radical-etching process, the electronic band structure is the same ”.

[1] F. Yang et al., Physical review letters 109, 016801 (2012).
[2] Z. F. W. Lin Miao, Wenmei Ming, Meng-Yu Yao, Meixiao Wang, Fang Yang, Y. R. Song, Fengfeng Zhu, Alexei V. Fedorov, Z. Sun, C. L. Gao, Canhua Liu, Qi-Kun Xue, Chao-Xing Liu, Feng Liu, Dong Qian, and Jin-Feng Jia, Proceedings of the National Academy of Sciences 110, 2758 (2013).
[3] R. Shokri, H. L. Meyerheim, S. Roy, K. Mohseni, A. Ernst, M. M. Otrokov, E. V. Chulkov, and J. Kirschner, Physical Review B 91 (2015).
[4] A. J. C. J. Powell, S. Tanuma, D. R. Penn, H. Bethe, C. S. Fadley, W. S. M. Werner, L. Kover, J. Toth, D. Varga, J. G. Beamson, N. Moslemzadeh, P. Weightman, J. F. Watts., Figures for electron inelastic mean free paths for 41 elemental solids over 10 eV to 30,000 eV 2012), Database of electron inelastic mean free path for elemental solids, p.^pp. 19.
[5] J. D. Bourke and C. T. Chantler, Journal of Electron Spectroscopy and Related Phenomena 196, 142 (2014).
[6] K. v. Klitzing, Nobel lecture (1985).
[7] R. B. Laughlin, Nobel lecture (1998).
[8] D. C. Tsui, Nobel lecture (1998).
[9] H. L. Stormer, Nobel lecture (1998).
[10] 王律堯, 台灣磁性技術協會會訊 49 (2009).
[11] J. Wunderlich, B. Kaestner, J. Sinova, and T. Jungwirth, Physical review letters 94, 047204 (2005).
[12] C. A. Hoffman, J. R. Meyer, F. J. Bartoli, A. Di Venere, X. J. Yi, C. L. Hou, H. C. Wang, J. B. Ketterson, and G. K. Wong, Physical Review B 48, 11431 (1993).
[13] I. K. Drozdov, A. Alexandradinata, S. Jeon, S. Nadj-Perge, H. W. Ji, R. J. Cava, B. A. Bernevig, and A. Yazdani, Nature Physics 10, 664 (2014).
[14] C.-L. Gao, D. Qian, C.-H. Liu, J.-F. Jia, and F. Liu, Chinese Physics B 22, 067304 (2013).
[15] L.-Z. Yao, Master Thesis, National Sun Yat-sen University, 2014.
[16] 拓樸絕緣體簡介, (張天蓉).
[17] M.-C. Chang, in Berry phase in solid state physicsNational Taiwan Normal University, 2009), pp. 12.
[18] Y. Ando, Journal of the Physical Society of Japan 82, 102001 (2013).
[19] K. Kuroda et al., Physical review letters 105, 076802 (2010).
[20] X. Wang, G. Bian, T. Miller, and T. C. Chiang, Physical review letters 108, 096404 (2012).
[21] W. Zhang, R. Yu, H.-J. Zhang, X. Dai, and Z. Fang, New Journal of Physics 12, 065013 (2010).
[22] K. F. Zhang, F. Yang, Y. R. Song, C. Liu, D. Qian, C. L. Gao, and J.-F. Jia, Applied Physics Letters 107, 121601 (2015).
[23] C. Kittel, in Introduction to Solid State Physics, edited by 82005), pp. 7.
[24] Brillouin_zone, (en.wikipedia).
[25] Cubic_crystal_system, (en.wikipedia).
[26] Hexagonal_crystal_system, (https://en.wikipedia.org/wiki/Hexagonal_crystal_system).
[27] C. Kittel, in Introduction to Solid State Physics, edited by 82005), pp. 31.
[28] 同步加速器光源簡介, (NSRRC).
[29] P. J. Chou, Design Guidelines of Synchrotron Light Sources, 2014.
[30] BL21B U9-CGM Spectroscopy Beamline, (NSRRC).
[31] BL24A Wide Range SGM Beamline, (NSRRC).
[32] J. R. A. A.Y. Cho, Progress in Solid State Chemistry 10, 157 (1975).
[33] A. Damascelli, Physica Scripta. (2004).
[34] J. J. Sakruia, in Modern Quantum Mechaincs1994), p. 362.
[35] G. Somarjai, in Chemistry in two dimensions (Cornell University, 1981), p. 575.
[36] M. D. Seah, W., in Surf. Interface Anal1979), p. 1.
[37] C. Kittel, in Introduction to Solid State Physics, edited by 82005), p. 167.
[38] DA30-L, (Scientaomicorn).
[39] A. Damascelli*, REVIEWS OF MODERN PHYSICS 75, (2003).
[40] Scienta, Description of the Length Count Scienta, 2010), Scienta User Manual.
[41] X-ray photoelectron spectroscopy, (en.wikipedia).
[42] C.-Y. Lin, Master Thesis, National Tsing Hua University, 2013.
[43] Edwards nXDS10iC 7.5 cfm Chemical-Resistant Dry Scroll Pump, (Across International).
[44] Turbomolecular pump, (en.wikipedia).
[45] Turbo Molecular Pumps, (Osaka Vacuum, Ltd.).
[46] Ion_Pump_Operation, (Northern Arizona University).
[47] 鈦昇華幫浦, (baike).
[48] 真空狀態的達成 : 各種抽氣技術的介紹, (JunSun Tech.).
[49] W.-C. Chen, Master Thesis, National Tsing Hua University, 2011.
[50] N.-Y. Wang, Master Thesis, National Tsing Hua University, 2015.
[51] M. V. Kuznetsov et al., Physical Review B 91 (2015).
[52] M. Bianchi, D. Guan, S. Bao, J. Mi, B. B. Iversen, P. D. King, and P. Hofmann, Nature communications 1, 128 (2010).
[53] Q. D. Gibson et al., Physical Review B 88 (2013).
[54] F. Song, J. W. Wells, Z. Jiang, M. Saxegaard, and E. Wahlstrom, ACS applied materials & interfaces 7, 8525 (2015).
[55] X. He, W. Zhou, Z. Y. Wang, Y. N. Zhang, J. Shi, R. Q. Wu, and J. A. Yarmoff, Physical review letters 110, 156101 (2013).
[56] T. Hirahara et al., Physical review letters 109, 227401 (2012).