Surface Incident Metal-Semiconductor-Metal Ge Photodetectors on Si Substrate Fabricated by Rapid-Melting-Growth Method

• Main Authors: Wu, Ting-Hsiao, 吳庭孝
• Other Authors: LeeㄝMing-Chang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/14675352589340958796

碩士 === 國立清華大學 === 光電工程研究所 === 100 === Over decades, silicon semiconductor industry grows rapidly due to advanced CMOS technology as well as relatively low cost for silicon and stable material properties. Silicon-based optoelectronics, benefited from the matured IC industry, receives a lot of attention recently. One of the key applications is high-speed photodetectors for optical communication or optical links. However, Si is transparent for infrared wavelength that is usually used in optical communication. Other materials should be integrated on the Si optoelectronic devices to detect infrared signals. Ge is an ideal material for long wavelength absorption; meanwhile, Ge process is usually CMOS-compatible, indicating the possibility of mass production. Ge-based photodetectors on silicon substrate have been studied by several research groups. One of the key issues is difficult epitaxy of Ge on silicon due to lattice mismatch (4%). In this thesis, we propose using rapid melting growth method to grow high-quality monocrystal metal-semiconductor-metal Ge photodetectors on Si substrate with low thermal budget. By well selecting metal contact and Ge passivation, the device dark current was significant reduced by three orders of magnitude. Since the absorption layer is very thin, we propose back illumination or metallic grating couplers to enhance the responsivity.