Research group of Dr. Buwen Cheng from Institute of Semiconductors, Chinese Academy of Sciences, made progress on photodetectors on silicon-based photonics and published their work on ACS Appl. Mater. Interfaces.
Germanium-based photodetector is a key component in silicon based photonics because of its unique properties of response at telecommunication and compatibility with CMOS techniques. However, limitations of low quantum efficiency at NIR range and death region at visible range as well as high surface combination pull germanium photodetectors stand still in a circle for a long time. Research group of Dr. Buwen Cheng have demonstrated a germanium-graphene hybrid structure photodetector that consists of a 20 nm germanium layer and a monolayer graphene. Combining the advantages of graphene and germanium, the device achieves a broadband detection, a higher responsivity of 66.2 AW-1 and a larger conductive gain of 155 than pure germanium or graphene detectors. The improvement can attribute to the effective separation and transport of photo-generated carriers at the hybrid junction. Based on the above properties, the germanium-graphene hybrid photodetector presents a paradigm for realization of small but high performance device in the process of integration in silicon based optical chips. And it also offers new opportunities in imaging, sensing and other optoelectronic applications.