本論文使用化學氣相傳導法(Chemical Vapor Transport, CVT)並以碘(I2)作為傳導劑，成長硒化鍺(GeSe)與碲化鎵(GaTe)層狀半導體。針對此晶體進行能量散射光譜儀、X射線繞射儀結構的定性、定量分析，再透過光學與電性分析其物理特性。
首先，藉由能量散射光譜儀確認材料之元素比與預期成分相符，透過X射線繞射儀，得知硒化鍺為正交晶系，沿著[001]方向生長，其晶格常數分別為a=4.4Å、b=3.87 Å、c=10.81 Å，碲化鎵則為單斜晶系，其晶格常數分別為a=17.39 Å、b=10.45 Å、c=4.07 Å、=104.5゜。
接著，光學實驗部分，利用固態雷射作為激發光源，量測拉曼散射光譜可得到拉曼振動模態Ag與Bg會隨著光的偏振方向差異而有特定振動訊號，因此證明晶軸具有非均向特性。在光穿透光譜與壓電調制反射光譜實驗中，對不同晶軸方向進行極化實驗，發現近能隙的躍遷訊號有消長現象，可再次證明兩材料具有光學異向特性，且能得知碲化鎵為直接能隙半導體。因此在光激發螢光實驗中，低溫時碲化鎵可觀察到能隙附近有3個峰值訊號，分別為施體受體對(DAP)、束縛激子複合物(BECs)及自由激子(FX)，隨著溫度升高，束縛激子會快速衰減，自由激子則是逐漸明顯而且有紅移現象。
電性實驗部分，利用四點電阻率與霍爾量測，可計算出硒化鍺、碲化鎵之電阻率分別為4.42(Ω-cm)、1.01×104(Ω-cm)，進一步透過I-V曲線對兩材料進行照光，發現碲化鎵電流急劇上升，光導效率高達95%，最後在熱探針實驗中，兩材料呈現p型半導體特性。
透過以上這些光電物理特性研究，證實硒化鍺與碲化鎵皆具有良好的光電特性，且未來極具有潛力在光電元件及偏振元件上有所發展與應用。

Layered-type GeSe and GaTe crystals were grown by Chemical Vapor Transport (CVT) method using iodine (I2) as the transport agent. The required temperature of GeSe and GaTe were set at 600 °C and 900 °C with temperature gradient of -4° C/cm that could be grown for 8-10 days. Energy Dispersive Spectrometer (EDS) and X-ray Diffraction (XRD) were conducted to confirm that crystals grown through the CVT method were of high quality. The XRD result confirmed that GeSe is orthorhombic with lattice in constants of a=4.40 Å, b=3.87Å, and c=10.81Å. Moreover, GaTe crystallizes monoclinic stucture with lattice constants of a=17.39Å, b=11.45Å, c=4.07Å, and γ=104.5°, respectively. Both materials are stacking along c-axis with a longer crystal edge along b axis (in-plane). The Raman modes of the two materials showed selection rule for the linearly polarized lights along a and along b axis. Based on Piezoreflectance (PzR) and Transmittance experiments, the band gaps of GeSe and GaTe show polarization dependency with the linearly polarized lights along a and b axes. Because the results of PzR and Transmittance experiments are comparable near the band edge, we can conclude that GeSe and GaTe are direct semiconductors. From the temperature dependent experiment, we can find the band gap is red shift and lineshape is broadened with the temperature increased. In addition, micro-Photoluminescence (μPL) experiment of GaTe shows many of the near-band-edge emission features, including donor receptor pair (DAP), bound exciton complex (BECs), and free exciton (FX) detected at 4K. For Hall Effect measurement at 300K, the mobility of the crystals were determined to be 73.62cm3/v.s for GeSe and 16.55 cm3/v.s for GaTe, respectively. The four point probe measurements of GeSe and GaTe also show in-plane electrical anisotropy. GaTe have a high photoresponsivity of ∆ρ/ρ=95% under the illumination of Tungsten lamp of power density 10.4mW/cm2.From the hot probe measurement, the GeSe and GaTe belong to p-type semiconductors. From the optical and electrical measurement results, we know that both GeSe and GaTe can have photovoltaic and orientation character, and which possess the potential for application in the solar materials and polarized devices.

[1] Shaabani, L., Aminorroaya-Yamini, S., Byrnes, J., Akbar Nezhad, A., & Blake,
G. R. (2017). Thermoelectric Performance of Na-Doped GeSe. ACS Omega, 2(12),
9192-9198. doi:10.1021/acsomega.7b01364
[2] Xue, D. J., Liu, S. C., Dai, C. M., Chen, S., He, C., Zhao, L., Hu, J. S., &
Wan, L. J. (2017). GeSe Thin-Film Solar Cells Fabricated by Self-Regulated
Rapid Thermal Sublimation. J Am Chem Soc, 139(2), 958-965.
doi:10.1021/jacs.6b11705
[3] Hsueh, H.-C., Li, J.-X., & Ho, C.-H. (2018). Polarization Photoelectric
Conversion in Layered GeS. Advanced Optical Materials, 6(4), 1701194.
doi:10.1002/adom.201701194
[4] Huang, S., Tatsumi, Y., Ling, X., Guo, H., Wang, Z., Watson, G., Puretzky, A.
A., Geohegan, D. B., Kong, J., Li, J., Yang, T., Saito, R., & Dresselhaus, M.
S. (2016). In-Plane Optical Anisotropy of Layered Gallium Telluride. ACS
Nano, 10(9), 8964-8972. doi:10.1021/acsnano.6b05002
[5] Zhao, Q., Wang, T., Miao, Y., Ma, F., Xie, Y., Ma, X., Gu, Y., Li, J., He,
J., Chen, B., Xi, S., Xu, L., Zhen, H., Yin, Z., Li, J., Ren, J., & Jie, W.
(2016). Thickness-induced structural phase transformation of layered gallium
telluride. Phys Chem Chem Phys, 18(28), 18719-18726. doi:10.1039/c6cp01963c
[6] Gillan, E. G., & Barron, A. R. (1997). Chemical Vapor Deposition of Hexagonal
Gallium Selenide and Telluride Films from Cubane Precursors:  Understanding
the Envelope of Molecular Control. Chemistry of Materials, 9(12), 3037-3048.
doi:10.1021/cm9703886
[7] Ho, C. H., Wu, C. C., & Cheng, Z. H. (2005). Crystal structure and electronic
structure of GaSe1−xSx series layered solids. Journal of Crystal Growth,
279(3-4), 321-328. doi:10.1016/j.jcrysgro.2005.02.042
[8] Liberatore, M. J. (1995). Secondary-ion mass spectrometric analysis of
oxygen-grain boundary diffusion in magnesium-oxide bicrystals. Massachusetts
Institute of Technology.
[9] 何清華（1991）。二硫化鐵之單晶成長與特性研究。國立臺灣科技大學工程技術研究所碩士論文
[10] 柯宗佑（2014）。二硒化鉬鎢層狀半導體之晶體成長與光學特性研究。國立臺灣科技大學電子
工程系碩士論文
[11] 林文堯（2017）。硫化錫與硒化錫之晶體成長與光學特性研究。國立臺灣科技大學電子工程系
碩士論文
[12] Stallo, J. B. (1884). The concepts and theories of modern physics: D.
Appleton.
[13] Kittel, C., McEuen, P., & McEuen, P. (1976). Introduction to solid state
physics (Vol. 8): Wiley New York.
[14] Chang, Y. M., Kim, H., Lee, J. H., & Song, Y.-W. (2010). Multilayered
graphene efficiently formed by mechanical exfoliation for nonlinear
saturable absorbers in fiber mode-locked lasers. Applied Physics Letters,
97(21), 211102. doi:10.1063/1.3521257
[15] Seraphin, B. O., Hess, R. B., & Bottka, N. (1965). Field Effect of the
Reflectivity in Germanium. Journal of Applied Physics, 36(7), 2242-2250.
doi:10.1063/1.1714458
[16] Errandonea, D., Martínez-García, D., Segura, A., Haines, J., Machado-Charry,
E., Canadell, E., Chervin, J.C., & Chevy, A. (2008). High-pressure
electronic structure and phase transitions in monoclinic InSe: X-ray
diffraction, Raman spectroscopy, and density functional theory. Physical
Review B, 77(4), 045208. doi:10.1103/PhysRevB.77.045208
[17] Mathieu, H., Allegre, J., & Gil, B. (1991). Piezomodulation spectroscopy: A
powerful investigation tool of heterostructures. Phys Rev B Condens Matter,
43(3), 2218-2227. doi:10.1103/physrevb.43.2218
[18] Ho, C.-H., Lee, H.-W., & Cheng, Z.-H. (2004). Practical thermoreflectance
design for optical characterization of layer semiconductors. Review of
Scientific Instruments, 75(4), 1098-1102. doi:10.1063/1.1667255
[19] Pankove, J. I. (1975). Optical processes in semiconductors: Courier
Corporation.
[20] Viezbicke, B. D., Patel, S., Davis, B. E., & Birnie, D. P. (2015).
Evaluation of the Tauc method for optical absorption edge determination: ZnO
thin films as a model system. physica status solidi (b), 252(8), 1700-1710.
doi:10.1002/pssb.201552007
[21] 陳映岑（2014）。硒化銦之晶體成長及結構特性與光學應用研究。國立臺灣科技大學應用科技
研究所碩士論文
[22] Axelevitch, A., & Golan, G. (2013). Hot-probe method for evaluation of
majority charged carriers concentration in semiconductor thin films. Facta
universitatis - series: Electronics and Energetics, 26(3), 187-195.
doi:10.2298/fuee1303187a
[23] Zhang, X., Tan, Q. H., Wu, J. B., Shi, W., & Tan, P. H. (2016). Review on
the Raman spectroscopy of different types of layered materials. Nanoscale,
8(12), 6435-6450. doi:10.1039/c5nr07205k
[24] Wang, T., Zhao, Q., Miao, Y., Ma, F., Xie, Y., & Jie, W. (2018). Lattice
Vibration of Layered GaTe Single Crystals. Crystals, 8(2), 74.
doi:10.3390/cryst8020074
[25] Hsueh, H. C., Warren, M. C., Vass, H., Ackland, G. J., Clark, S. J., &
Crain, J. (1996). Vibrational properties of the layered semiconductor
germanium sulfide under hydrostatic pressure: Theory and experiment.
Physical Review B, 53(22), 14806-14817. doi:10.1103/PhysRevB.53.14806
[26] Ho, C.-H., & Liu, Z.-Z. (2019). Complete-series excitonic dipole emissions
in few layer ReS2 and ReSe2 observed by polarized photoluminescence
spectroscopy. Nano Energy, 56, 641-650. doi:10.1016/j.nanoen.2018.12.014
[27] Ho, C. H., & Lin, S. L. (2006). Optical properties of the interband
transitions of layered gallium sulfide. Journal of Applied Physics, 100(8),
083508. doi:10.1063/1.2358192
[28] Cai, H., Chen, B., Wang, G., Soignard, E., Khosravi, A., Manca, M., Marie,
X., Chang, L.Y., Urbaszek,B., & Tongay, S. (2017). Synthesis of highly
anisotropic semiconducting GaTe nanomaterials and emerging properties
enabled by epitaxy. Advanced Materials, 29(8), 1605551.
doi:10.1002/adma201605551
[29] Fang, Y., Wang, L., Sun, Q., Lu, T., Deng, Z., Ma, Z., Jiang, Y., Jia, H.,
Wang, W., Zhou, J., & Chen, H. (2015). Investigation of temperature-
dependent photoluminescence in multi-quantum wells. Scientific Reports, 5,
12718. doi:10.1038/srep1271