Zero-Bias Operation of CVD Graphene Photodetector with Asymmetric Metal Contacts

The responsivity of a graphene photodetector was substantially enhanced by modulating the potential gradient in a chemical vapor deposition-grown graphene channel using asymmetric metal contacts such as Ti, Pd, and Au for the source and drain. The photoresponsivity of a graphene photodetector with an asymmetric Au–Ti contact combination increased to 52 mA/W at an illumination power density of 0.25 μW/cm2; this photoresponsivity is ∼63 times higher than that of a graphene photodetector having a symmetric Au–Au contact combination (0.82 mA/W).