Analysis of graphene nanoribbon quantum well photodetectors

Abstract

One dimensional (1D) quantum well (QW) formation and energy state confinement in armchair graphene nanoribbon (A-GNR) heterostructures have been studied. 1D confinement creates both confined and quasi-continuous states within the well.Asinfiniteconfinement exists in two direction (being monolayer and finite width), density of states shows quantum wire like nature. Depending on the bandgap of channel A-GNR confined states can be raised above well barrier. A photodetector device structure based on A-GNR-QW has been proposed to incorporate both interband and intersubband optical transition using a back gate potential. Contacts are made by semi-metallic A-GNR to discard the effects of metal-GNR schottkey contact. Photocurrent, dark current and quantum efficiency of different A-GNR-QW photodetector structures are measured using self-consistent simulation between Non-Equilibrium Green‟s function Formalism including electron-photon interaction and Poisson‟s equation. Device Hamiltonian is based on tight-binding model. The algorithm is calibrated and benchmarked by well-known RTD photodetector structure using effective mass based Hamiltonian. The simulation results for A-GNR based QW structures show optical detection from short wavelength infrared (SWIR) to ultraviolet (UV) range having a tunable feature through back gate potential, which makes the proposed device a promising candidate for future optoelectronics. In contrast to conventional III-V heterostructure based QW photodetector, A-GNR based QW photodetector is designed for working as interband and intersubband photodetector without doping the channel material. As the channel is undoped, higher photocurrent response is possible to observe.