Hybrid QD – Graphene/2DEG Semiconductor Phototransistors: Performance and Gate Tuning

Hybrid phototransistors combine solution processed colloidal semiconductor quantum dots (QDs) with graphene or two-dimensional (2D) semiconductor materials. While the outstanding performance of these devices has been already demonstrated, their photoreponse and noise characteristics have not understood yet. We have generalized the traditional “semiconductor” photoresponse model to the weakly degenerate optoelectronic materials. The presented model describes well the responsivity as a function of the electromagnetic power and material parameters. We also calculate and analyze the noise characteristics related to generation-recombination processes. We determine limiting characteristics of hybrid phototransistors and compare the theoretical limitations with available experimental results. We also analyze and compare advantages and disadvantages of graphene and 2D semiconductor materials for use in hybrid phototransistors. Finally, we calculate tradeoff detector characteristics depending on the gate voltage and examine perspectives of these detectors for adaptive sensing with tunable photodetector parameters.