Highly sensitive, ultrafast photo-thermoelectric graphene THz detector

We demonstrate a THz detector that is made of high-quality graphene and is based on the photo-thermoelectric (PTE) effect: absorbed THz light leads to hot-carriers that generate a photoresponse at a junction between two graphene regions with different carrier density, ideally a pn-junction. Our photodetector combines a device geometry that is optimized for the PTE effect with an antenna that focuses the THz light at the pn-junction. We find that the noise-equivalent power (NEP) at room temperature is < 200 mathrm{pW}/sqrt{mathrm{Hz}}, while the response time is < 40 ns (limited by the measurement setup)-many orders of magnitude faster than commercial room temperature detectors.