Combined thermionic and field emission reverse current for ideal graphene/n‐Si Schottky contacts in a modified Landauer formalism

Abstract

AbstractFundamental understanding of carrier transport is needed for current graphene‐based devices (e.g. graphene based Schottky diodes, FET geometries, solar cells) involving single layer graphene grown directly over n‐ or p‐ type semiconductors. In an intimate (ideal) G/n‐Si junction under reverse bias, carriers may (a) tunnel through the junction and/or (b) thermionically overcome the junction barrier. Tunneling occurring at the junction is in essence thermionic field emission of carriers with energy levels below the junction barrier, with a less‐than‐one tunneling probability; thermal escape may occur as long as carriers have sufficient energy to overcome the barrier at the interface. The total current is expected to be the sum of two current components, thermionic emission (TE) and thermionic field emission (TFE), respectively, representing carriers surmounting and tunneling through the barrier, in the form I = ITE + ITFE, and is strongly dependent on temperature and doping. Specifically, we derive explicit results for both currents within the general Schottky diode current‐voltage characteristic: I = Io (eqV/kT–1). The combined current prefactor includes strong dependencies on (a) temperature as T3/2 and T5/2 for TE and TFE components, respectively, (b) junction barrier qΦB, (c) graphene layer thickness δ and (d) different Richardson constants for both components. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)