Photo-thermoelectric effect-driven detection of optical communication light in graphene/hBN heterostructures

We report on the photodetection properties of high-quality graphene encapsulated by hexagonal boron nitride under illumination with optical communication light. We demonstrate a gate-tunable photocurrent and zero-bias switching cycle operation at RT. Through gate and temperature-dependent photocurrent measurements, we determine that the dominant photoresponse mechanism is the photo-thermoelectric effect. At low temperatures, the photocurrent in finite doping regions correlates with the Seebeck coefficient, while sharp peaks emerge near the charge neutrality point due to an edge-excited photocurrent. Our study provides guidelines for high-performance graphene-based optoelectronic devices.