隨著電晶體不斷的微縮，為了解決傳統矽材料半導體所不能達到的材料限制，所以具有高載子遷移率、合適能隙及大的面積對體積比的二維材料成為研究的主流。
硒氧化鉍同時具有高載子遷移率、可透過材料厚度調變的能隙及高的環境穩定性使其在眾多二維材料中獲得注視。在光學上硒氧化鉍具有很寬廣的響應頻譜從可見光至近紅外光，由於硒氧化鉍不具有表面陷阱態及淺缺陷能量所以其光響應度具有很高的穩定性，也因為其高載子遷移率和在近紅外光波段合適的能隙所以具有高靈敏度和快速的響應時間。
在此篇論文中，我們使用熱化學氣相沉積法來成長硒氧化鉍，並控制成長溫度、時間、氣體流量及擺放位置來優化硒氧化鉍成長的大小，也成功的成長出200微米之硒氧化鉍晶體，搭配光學顯微鏡、拉曼光譜儀和原子力顯微鏡來分析材料。在元件製程上我們使用了二種不同的基板，利用黃光微影的方式完成元件製作，並搭配適合公函數的金屬電極避免和硒氧化鉍產生蕭基障蔽，最後利用三種不同波長的二極體雷射，包含紅光(633nm)、綠光(532nm)及藍光(405nm)，去比較不同波長、功率及不同基板對硒氧化鉍元件的光導電特性。

Bi2O2Se is an emerging 2-D material with promising potential for futuristic semiconductor electronics. However, chemically vapor deposition of monolayer and few-layer films on desirable substrates for practical applications is difficult and only few research groups have successfully synthesized it in the past several years. In this thesis, synthesis of Bi2O2Se by thermal chemical vapor deposition using controlled growth temperature, process time, gas flow rate and sample arrangement to optimize the domain size of Bi2O2Se, finally we deposit Bi2O2Se crystal with domain size lager than 200μm. Also we use optical microscopes, raman spectrum and atomic force microscopes to analyze the quality of Bi2O2Se crystal. On device fabrication, we use two different substrate and suitable work function metal electrode avoiding form Schottky barrier. The device is measured for photoconductivity under three different wave length, 405nm, 532nm, 633nm. Comparing different wavelength, power and substrate to the photoconductivity of the device.

[1] J. Bardeen and W. H. J. P. o. t. I. Brattain, "The transistor, a semiconductor triode," Engineering Science & Education Journal, vol. 86, no. 1, pp. 29-30, 1998.
[2] A. K. Geim and K. S. Novoselov, "The rise of graphene," in Nanoscience and Technology: A Collection of Reviews from Nature Journals: World Scientific, 2010, pp. 11-19.
[3] M. I. J. M. t. Katsnelson, "Graphene: carbon in two dimensions," Elsevier, vol. 10, no. 1-2, pp. 20-27, 2007.
[4] A. Splendiani et al., "Emerging photoluminescence in monolayer MoS2," ACS Publications, vol. 10, no. 4, pp. 1271-1275, 2010.
[5] X. Li and H. J. J. o. M. Zhu, "Two-dimensional MoS2: Properties, preparation, and applications," Elsevier, vol. 1, no. 1, pp. 33-44, 2015.
[6] Z. Wang, B. J. E. s. Mi, and technology, "Environmental applications of 2D molybdenum disulfide (MoS2) nanosheets," ACS Publications, vol. 51, no. 15, pp. 8229-8244, 2017.
[7] "http://www.ndl.org.tw/docs/publication/21_3/pdf/D3.pdf."
[8] Jinxiong Wu et al., "Controlled Synthesis of High-Mobility Atomically Thin Bismuth Oxyselenide Crystals," Nano Lett., vol. 17, no. 5, pp. 3021-3026, 2017.
[9] J. Wu et al., "High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi 2 O 2 Se," Nature, vol. 12, no. 6, p. 530, 2017.
[10] J. Li et al., "High‐Performance Near‐Infrared Photodetector Based on Ultrathin Bi2O2Se Nanosheets," Advanced Functional Materials, vol. 28, no. 10, p. 1706437, 2018.
[11] U. Khan et al., "Controlled Vapor–Solid Deposition of Millimeter‐Size Single Crystal 2D Bi2O2Se for High‐Performance Phototransistors," Advanced Functional Materials, p. 1807979, 2019.
[12] J. Wu et al., "Low Residual Carrier Concentration and High Mobility in 2D Semiconducting Bi2O2Se," Nano letters, vol. 19, no. 1, pp. 197-202, 2018.
[13] J. Wu et al., "Chemical Patterning of High‐Mobility Semiconducting 2D Bi2O2Se Crystals for Integrated Optoelectronic Devices," Advanced Materials, vol. 29, no. 44, p. 1704060, 2017.
[14] Q. Fu et al., "Ultrasensitive 2D Bi2O2Se Phototransistors on Silicon Substrates," Advanced Materials, p. 1804945, 2018.
[15] J. Yin et al., "Ultrafast and highly sensitive infrared photodetectors based on two-dimensional oxyselenide crystals," Nature, vol. 9, no. 1, p. 3311, 2018.
[16] G. Konstantatos et al., "Hybrid graphene–quantum dot phototransistors with ultrahigh gain," Nature, vol. 7, no. 6, p. 363, 2012.
[17] M. M. Furchi, D. K. Polyushkin, A. Pospischil, and T. J. N. l. Mueller, "Mechanisms of photoconductivity in atomically thin MoS2," ACS Publications, vol. 14, no. 11, pp. 6165-6170, 2014.
[18] A. Gurarslan et al., "Surface-energy-assisted perfect transfer of centimeter-scale monolayer and few-layer MoS2 films onto arbitrary substrates," ACS Publications, vol. 8, no. 11, pp. 11522-11528, 2014.