Monolayer Graphene/Germanium Schottky Junction As High-Performance Self-Driven Infrared Light Photodetector

We report on the simple fabrication of monolayer graphene (MLG)/germanium (Ge) heterojunction for infrared (IR) light sensing. It is found that the as-fabricated to Schottky junction detector exhibits obvious photovoltaic characteristics, and is sensitive to IR light with high I-light/I-dark ratio of 2 x 10(4) at zero bias voltage. The responsivity and detectivity are as high as 51.8 mA W-1 and 1.38 x 10(10) cm Hz(1/2) W-1, respectively. Further photoresponse study reveals that the photovoltaic IR detector displays excellent spectral selectivity with peak sensitivity at 1400 nm, and a fast light response speed of microsecond rise/fall time with good reproducibility and long-term stability. The generality of the above results suggests that the present MLG/Ge IR photodetector would have great potential for future optoelectronic device applications.