本論文利用化學氣相傳導法 (Chemical Vapor Transport method，CVT）成長硒化銦系列晶體，目前成功成長出α-In2Se3層狀單晶, 之後進行晶體結構與光學特性分析。藉由能量散佈儀 (Energy dispersive X-ray spectrometer, EDS)量測可以確定成長材料之元素比與預期相符合。而利用X-ray晶格繞射 (X-ray diffraction, XRD)以及穿透式顯微鏡 (Transmission electron microscopy, TEM)分析可得到α-In2Se3為六方體系結構 (Hexagonal structure)且為Alpha結晶相。在光學量測上，α-In2Se3的近能隙傳導機制，可使用熱調制、壓電調制以及穿透實驗得出材料為直接能隙半導體且常溫300 K之能隙為1.453 eV，同時藉由溫度相依熱調制光譜之半高寬比變化量很小的結果可以推斷樣品應屬於缺陷型半導體，而缺陷主要是與Se空缺、In空缺以及In間隙等空缺相關型式存在。
　　α-In2Se3能隙以下的傳導訊號可以利用光導實驗來觀察到，而在高於能隙上之傳導訊號主要可以利用表面光電壓、表面光電導以及光致螢光光譜來觀察，這些高於能隙上的訊號推測是來自於樣品表面所生成之表面氧化態，其型式推測可能為α-In2Se3-3xO3x.
　　根據實驗結果驗證，這些低於能隙之缺陷態可以用來幫助吸收近紅外波段的能量，而高於能隙的能量則可利用樣品上的表面氧化態來輔助吸收，因此利用以上的實驗結果，實際應用上也製成光導型以及表面光電導型之原型光檢測器，利用此光檢測器之光導及表面光電導模式切換可以涵蓋近紅外至藍紫外光波段的檢測範圍。

　　Single crystals of α-In2Se3 were grown by chemical vapor transport method using ICl3 as a transport agent. X-ray diffraction and transmission electron microscopy (TEM) measurements confirmed hexagonal structure and alpha phase for the as-grown indium selenide layer crystals. Energy dispersive spectroscopy (EDS) analysis verified the stoichiometry of the α-In2Se3 compound.
　　The near-band-edge transitions of α-In2Se3 were characterized experimentally by thermoreflectance (TR), piezoreflectance (PzR) and transmission measurements. The experimental results confirmed that α-In2Se3 is a direct semiconductor with energy gap of 1.453 eV at 300 K. The broadening parameters of TR spectra do not change from 30 K to 300 K inferred that α-In2Se3 is a defect semiconductor with some vacancy-related defects (e.g. selenium vacancies, indium vacancies or In interstitials) inside the crystal.
　　Photoconductiviy (PC) measurement was used for characterization of defect transitions below band edge of indium selenide. The above band-edge transitions of α-In2Se3 have been evaluated by surface photovoltage (SPV), surface photo-conductive response (SPR) and photoluminescence (PL) experiments. The above band-edge transitions may come from surface oxidation states (α-In2Se3-3xO3x) existed on the α-In2Se3’s surface. The below-band-edge defect states facilitate the absorption of near-infrared (NIR) region and surface oxidation states absorb blue-to-UV portion. Based on our experimental results, the prototype of PC and SPR photodetectors of α-In2Se3 has been made, which shows promotion of optical absorption from NIR to UV range.

[1]D. Hariskos, S. Spiering, and M. Powalla,“Buffer layers in Cu(In,Ga)Se2 solar cells and modules,”Thin Solid Films, vol. 480-481, pp. 99-109, 2005.
[2]D. K. Nagesha, X. Liang, A. A. Mamedov, G. Gainer, M. A. Eastman, M. Giersig, J.-J. Song, T. Ni, and N. A. Kotov,“In2S3 nanocolloids with excitonic emission:  In2S3 vs CdS comparative study of optical and structural characteristics,”J. Phys. Chem. B, vol. 105, pp. 7490-7498, 2001.
[3]R. Jayakrishnan, T. Sebastian, T. T. John, C. S. Kartha, and K. P. Vijayakumar,“Photoconductivity in sprayed β-In2S3 thin films under sub-band-gap excitation of 1.96 eV,”J. Appl. Phys., vol. 102, pp. 043109, 2007.
[4]Capasso, F. and G. Maragaritondo, Heterojunction Band Discontinuities:Physics and Device Application. Elsevier science, 1987.
[5]J. C. W. Folmer, J. A. Turner, R. Noufi, and D. Cahen,“Structural and solar conversion characteristics of the (Cu2Se)X(In2Se3)1-X cystem,”J. Electrochem. Soc., vol. 132, pp. 1319-1327, 1985.
[6]J. Herrero and J. Ortega,“Electrochemical synthesis of photoactive In2Se3 thin films,”Solar Energy Materials, vol. 16, pp. 477-485, 1987.
[7]A. Likforman, P.-H. Fourcroy, M. Guittard, J. Flahaut, R. Poirier, and N. Szydlo,“Transitions de la forme de haute temperature α de In2Se3, de part et d'autre de la temperature ambiante,”J. Solid State Chem., vol. 33, pp. 91-97, 1980.
[8]M. Peršin, A. Peršin, B. Čelustka, and B. Etlinger,“Properties of flash evaporated thin films of In2Se3,”Thin Solid Films, vol. 11, pp. 153-160, 1972.
[9]C. Julien, M. Eddrief, K. Kambas, and M. Balkanski,“Electrical and optical properties of In2Se3 thin films,”Thin Solid Films, vol. 137, pp. 27-37, 1986.
[10]H. M. Oh and C. D. Kim,“Growth and characterization of α-In2Se3 single crystals grown by using the chemical transport reaction technique,”Journal of the Korean Physical Society, vol. 43, pp. 312-314, 2003.
[11]S. Popovic, A. Tonejc, B. Grzeta-Plenkovic, B. Celustka, and R. Trojko,“Revised and new crystal data for indium selenides,”J. Appl. Crystallogr., vol. 12, pp. 416-420, 1979.
[12]S. Marsillac, A. M. Combot-Marie, J. C. Bernede, and A. Conan, “Experimental evidence of the low-temperature formation of γ-In2Se3 thin films obtained by a solid-state reaction,”Thin Solid Films, vol. 288, pp. 14-20, 1996.
[13]H. Lutz, Universitat Siegen, Anorgnische Chemie I, West Germany., Private Communication, 1989.
[14]S. Marsillac, J. C. Bernede, R. Ny, and A. Conan,“A new simple technique to obtain In2Se3 polycrystalline thin films,”Vacuum, vol. 46, pp. 1315-1323, 1995.
[15]H. Peng, C. Xie, D. T. Schoen, and Y. Cui,“Large anisotropy of electrical properties in layer-Structured In2Se3 nanowires,”Nano Lett., vol. 8, pp. 1511-1516, 2008.
[16]張國仁,「硒化銦與銅銦鎵硒成長與特性之研究」,博士論文, 光電科學研究所, 國立中央大學, 2006.
[17]何清華, 「二硫化鐵之單晶成長與特性研究」, 碩士論文, 工程技術研究所, 國立台灣工業技術學院, 1991.
[18]B. O. Seraphin,“The effect of an electric field on reflectivivty of germannium,”Proc. 7th int. Conf. Phys. Semicond, Academic, Dunod, Paris., 1964.
[19]M. Cardona, In Modulation spectroscopy. Academic Press, New York, 1969.
[20]D. E. Aspnes, Modulation spectroscopy/electric field effects on the dielectric function of semiconductors in handbook on semiconductors. Vol.2, Ed. By M. Balkanski, North HollandPublishing Co, Amsterdam, pp.109-154, 1980.
[21]A. K. Berry, D. K. Gaskill, G. T. Stauf, and N. Bottka, “Photoreflectance of semi-insulating InP: resistivity effects on the exciton phase,” Appl. Phys. Lett., vol. 58, pp. 2824, 1991.
[22]S. E. Acosta-Ortiz and A. Lastras-Martinez, “Electro-optic effects in the optical anisotropies of (001) GaAs,” Physical Review B, vol. 40, pp. 1426-1429, 1989.
[23]P. Lorrain and D. R. Corson, Electromagnetic Fields and Wave. JWANG YUAN Publishing CO. , Taipei, Taiwan, pp.508-511,1972.
[24]C. H. Ho, “Optical study of the structural change in ReS2 single crystals”Opt. Express, vol. 13, 2005.
[25]C. H. Ho,“Enhanced photoelectric-conversion yield in niobium-incorporated In2S3 with intermediate band,” J. Mater. Chem., vol. Opt. Express 21, pp. 10518-10524, 2011.
[26]C. H. Ho, “Growth and characterization of near-band-edge transitions in β-In2S3 single crystals,” J. Cryst. Growth, vol. 312, pp. 2718-2723, 2010.
[27]C. H. Ho, M. H. Hsieh, and C. C. Wu, “Photoconductance and photoresponse of layer compound photodetectors in the UV-visible region,” Rev. Sci. Instrum., vol. 77, pp. 113102, 2006.
[28]C. H. Ho,“The study of below and above band-edge imperfection states in In2S3 solar energy materials,”Physica B: Condensed Matter.
[29]C. S. Lynn, M. A. Susan and J. D, Michael,“Novel, colloidally rough, In203 films displaying high quantum efficiencies,”J Electrochem. Soc, vol. 133, pp. 716, 1986.