Graphene field effect transistors (GFETs) fabricated by chemical vapor deposition graphene deposited onto SiC substrates exhibit sensitivity to broadband visible light. The hysteretic nature of this GFET type was studied utilizing a new current-voltage measurement technique in conjunction with current-time measurements. This measurement method accounts for hysteretic changes in graphene response and enables transfer measurements that can be attributed to fixed gate voltages. Graphene hysteresis is shown to be consistent with electrochemical p-type doping, and current-time measurements clearly resolve a hole to electron to hole carrier transition in graphene with a single large change in gate voltage. V

We are developing detector architectures and devices based on the novel carbon nanomaterial graphene, which has been shown to exhibit unusual electrical properties of potential use for next-generation radiation detectors. Of particular interest is the use of this technology to develop novel neutron detectors.To this end, we are studying architectures based on a neutron absorbing converter material in conjunction with a graphene field-effect transistor (GFET). As an intermediate step towards the demonstration of GFET neutron detectors we utilize an alpha source to systematically study the effect of charge deposition on the device response. As an added benefit, this experiment helps us elucidate the important systematics of response to other types of radiation, including the dependence of the magnitude of graphene resistance modulation on the deposited energy and the dependence of device speed on the morphology of energy deposition.