Universal Scaling Laws in Schottky Heterostructures Based on Two-Dimensional Materials

TL;DR

This paper uncovers universal temperature scaling laws in carrier transport for 2D-material-based Schottky heterostructures, revealing fundamental physics and aiding device engineering.

Contribution

It introduces a universal scaling law for thermionic current in 2D heterostructures, resolving previous conflicts and extending understanding across various 2D materials.

Findings

Universal scaling law with $eta=3/2$ for lateral structures

Universal scaling law with $eta=1$ for vertical structures

Agreement with recent experimental data

Abstract

We identify a new universality in the carrier transport of two-dimensional(2D)-material-based Schottky heterostructures. We show that the reversed saturation current ($\mathcal{J}$) scales universally with temperature ($T$) as $ \log(\mathcal{J}/T^{\beta}) \propto -1/T$, with $\beta = 3/2$ for lateral Schottky heterostructures and $\beta = 1$ for vertical Schottky heterostructures, over a wide range of 2D systems including nonrelativistic electron gas, Rashba spintronic system, single and few-layer graphene, transition metal dichalcogenides and thin-films of topological solids. Such universalities originate from the strong coupling between the thermionic process and the in-plane carrier dynamics. Our model resolves some of the conflicting results from prior works and is in agreement with recent experiments. The universal scaling laws signal the breakdown of $\beta=2$ scaling in the classic diode equation widely-used over the past 60 years. Our findings shall provide a simple analytical scaling for the extraction of the Schottky barrier height in 2D-material-based heterostructure, thus paving way for both fundamental understanding of nanoscale interface physics and applied device engineering.