Interface Defect Engineering for Improved Graphene-Oxide-Semiconductor Junction Photodetectors

The deeply depleted graphene-oxide-semiconductor (D(2)GOS) junction detector provides an effective architecture for photodetection, enabling direct readout of photogenerated charge. Because of an inherent gain mechanism proportional to graphene's high mobility (mu), this detector architecture exhibits large responsivities and signal-to-noise ratios (SNR). The ultimate sensitivity of the D(2)GOS junction detector may be limited, however, because of the generation of dark charge originating from interface states at the semiconductor/dielectric junction. Here, we examine the performance limitations caused by dark charge and demonstrate its mitigation via the creation of low interface defect junctions enabled by surface passivation. The resulting devices exhibit responsivities exceeding 10 000 A/W-a value which is 10x greater than that of analogous devices without the passivating thermal oxide. With cooling of the detector, the responsivity further increases to over 25 000 A/W, underscoring the impact of surface generation on performance and thus the necessity of minimizing interfacial defects for this class of photodetector.