Anomalous Temperature Dependence of Current-Voltage Characteristics Observed in Graphene/n-Si(100) Junction

Abstract

Here, we report a switching of rectification polarity at ~17.5 K in the graphene/n-Si(100) Schottky junction. The comparative study between Pt/n-Si(100) and graphene/n-Si(100) is conducted to figure out the origin of the temperature-driven reversal of the rectification direction. For both junctions, the series resistance is around 1 KΩ and increases up to a few MΩ scale as the temperature goes down to 40 K. Very interestingly, the series resistance in the graphene/n-Si(100) junction starts increasing abruptly from ~40 K and reaches up to the GΩ range at lower temperatures. One plausible mechanism for the significant increase of series resistance below ~40 K is that the inelastic scattering time for electron in graphene can exceed the average travel time for an electron, injected from the Si substrate into the graphene layer, to make a round trip through the graphene layer and come back to the graphene/Si interface at sufficiently low temperatures. In this case, most of the electrons injected into the graphene layer will eventually go back to the Si substrate and then the associated electron injection rate will decrease substantially. With the Monte Carlo simulation, we demonstrate that the inter-dimensional carrier injection between the 3D Si substrate and the 2D graphene layer indeed can become drastically asymmetric with the inelastic scattering time for electron being elongated and is responsible for the temperature-dependent switching of rectification polarity.