Temperature-Driven Rectification Reversal Observed in Graphene/n-Si(100) Junction

Abstract

The electrical properties of graphene/semiconductor Schottky junctions have conventionally been explained by the thermionic emission of massless 2D Diracfermions and the modulation of graphene work-function triggered by the applied bias voltage. So far, most experiments have been conducted attemperatures higher than 77 K, resulting in limited insights into the charge carrier transport across the graphene/semiconductor junction at even lowertemperatures. In this study, we present an intriguing phenomenon involving the reversal of rectification direction in the graphene/n-Si(100) junction atapproximately 17.5 K. This phenomenon cannot be adequately explained by the existing concepts presented in prior reports. We propose that thetemperature-driven rectification reversal originates from the Schottky barrier lowering associated with graphene doping, inhomogeneity of interface energybarrier, and asymmetric nature of inter-dimensional carrier injection between 2D graphene and 3D Si substrate. The asymmetry of carrier injection at thegraphene/Si junction can be explained by our hypothesis that the ultra-thin graphene layer enables hot electrons to make multiple attempts of carrier injectionfrom graphene layer into Si substrate before they thermally equilibrate within the graphene layer. The Monte Carlo simulation reveals that the carrier injectionbetween graphene layer and Si substrate becomes increasingly asymmetric as temperature goes down, accompanied by a reduction in the inelasticscattering rate within the graphene layer. These findings offer a new concept of asymmetric inter-dimensional carrier injection, paving the way for realizing anovel type of Schottky diode in which the rectification polarity is controlled by temperature.

*NRF-2015H1A2A1033714, NRF-2023R1A2C1006519, SRFC-TA1903-02