Design and simulation of a graphene DEPFET detector

Graphene field effect transistors (GFETs) fabricated on undoped semiconductor substrates have shown promise for sensing ionizing radiation with a potential of high sensitivity, low noise, low power, and room temperature operation. Radiation detection with GFET is based on the high sensitivity of graphene resistivity on local electric field perturbations caused by ionized charges generated in an electrically biased radiation absorbing semiconductor substrate. Those charges are drifted to the neighborhood of graphene by the gate voltage applied across the detector. GFET radiation sensors can be fabricated on a variety of substrates, exploiting their distinct material properties, to address different application regimes. The current simple GFETs lack the functionality of efficiently removing ionized charges accumulated underneath graphene after signal readout, which results in a slow response to irradiation cut-off and therefore compromises the ability to operate in the pulse mode. In order to overcome this limitation, we propose here a more advanced device architecture, namely, graphene DEPFET.