Graphene field effect transistor as a strongradiationstrong and photo.pdfVIP

Invited Paper Graphene field effect transistor as a radiation and photo detector a a b a,c Ozhan Koybasi , Isaac Childres , Igor Jovanovic ,Yong P. Chen* aDept. of Physics, Purdue University, West Lafayette, IN 47907 bDept. of Mechanical and Nuclear Engineering, Penn State University, University Park, PA, 16802 cBirck Nanotechnology Center and School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907 ABSTRACT We exploit the dependence of the electrical conductivity of graphene on a local electric field, which can be abruptly changed by charge carriers generated by ionizing radiation in an absorber material, to develop novel high- performance radiation sensors for detection of photons and other kinds of ionizing radiation. This new detection concept is implemented by configuring graphene as a field effect transistor (FET) on a radiation-absorbing undoped semiconductor substrate and applying a gate voltage across the sensor to drift charge carriers created by incident photons to the neighborhood of graphene, which gives rise to local electric field perturbations that change graphene resistance. Promising results have been obtained with CVD graphene FETs fabricated on various semiconductor substrates that have different bandgaps and stopping powers to address different application regimes. In particular, graphene FETs made on SiC have exhibited a ~200% increase in graphene resistance at a gate voltage of 50 V when exposed to room light at room temperature. Systematic studies have proven that the observed response is a field effect. Keywords: graphene, tr