Abstract
Over decades, silicon semiconductor industry grew rapidly due to the advancement of CMOS fabrication technology, as well as the relatively low cost and good material stability. Recently, silicon-based optoelectronics that is capable of being integrated with modern IC receives a lot of attention. One of the key applications is high-speed photodetector for telecommunication and optical interconnect. However, Si is transparent at infrared wavelengths that are usually used in optical communication. Other materials should be used in adjunction with Si substrate to detect infrared signals. Ge is an ideal material for long wavelength absorption;moreover, Ge process is CMOS process-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 the difficulty in epitaxy growth of Ge on silicon due to lattice mismatch (4%). In this paper, we apply rapid melting growth method to grow high-quality single-crystal metal-semiconductor-metal Ge photodetectors on oxide with low thermal budget. By carefully selecting the metal contact and Ge passivation, the device dark current is significantly reduced by three orders of magnitude compared to the state-of-art literature data.