ABSTRACT

This chapter reviews photodetection technologies based on three material systems: semiconductors, low-dimensional materials, and metals. It discusses the photodetection technologies based on InGaAs, Ge, and all-Si. The chapter introduces the development of photodetectors based on low-dimensional materials and discusses different metallic photodetectors including quantum-tunneling based types. To achieve high performance and CMOS-compatible photodetection, an appropriate material system is necessary and several have been aggressively investigated in the past 30 years. The commonly adopted photodetection mechanism utilizes inter-band transitions in semiconductors to absorb photons, where the operation wave- length can be adjusted by proper selection of existing semiconductor materials or creation of the required bandgaps with band-engineering techniques. A number of semiconductor systems have been verified with photodetection capability including Si, Ge, and InGaAs. Recently, low-dimensional materials such as graphene, carbon nanotubes and noble metals have been explored for next generation PDs.