Previous research has already demonstrated that graphene field effect transistors can be operated at incredibly high bandwidths, demonstrating 25+GHz with a theoretical limit of up to 500GHz for visible photodetection. Ultrafast photodetection has also been demonstrated on the 10s of femtosecond scale via the photothermoelectric effect for visible photodetection. Detection at X-ray energies has been achieved using a graphene field effect transistor structure for pulsed X-ray photons, but has not been achieved for single X-ray photons; this would provide a route to faster and easier X-ray photodetection in medical physics and X-ray astronomy, among other areas. For terahertz detection, techniques have been used to detect terahertz photons but with slow bandwidths (as low as 1Hz) using a number of techniques; these have often investigated frequencies up to 100s GHz. Little research investigates detection for frequencies greater than 1THz – this would open up new areas for exploitation by industry and scientific research such as security and communications applications.