Ultrafast intrinsic optical-to-electrical conversion dynamics in a graphene photodetector

Optical-to-electrical conversion in graphene is a central phenomenon for realizing anticipated ultrafast and low-power-consumption information technologies. However, revealing its mechanism intrinsic timescale require uncharted terahertz electronics device architectures. Here we succeeded resolving optical-to-electrical processes high-quality via the on-chip electrical readout of an photothermoelectric current. By suppressing time constant resistor–capacitor circuit using resistive zinc oxide top gate, constructed gate-tunable photodetector with bandwidth up to 220 GHz. Measuring non-local photocurrent dynamics, found that extraction from electrode quasi-instantaneous without measurable carrier transit across several-micrometre-long graphene, following Shockley–Ramo theorem. The generation exceptionally tunable immediate >4 ps, origin identified as Fermi-level-dependent intraband carrier–carrier scattering. Our results bridge gap between optical science engineering, accelerating optoelectronic applications. Researchers demonstrated This was achieved by ‘RC’ gate.