Tunable Ohmic contact in graphene/HfS$_2$ van der Waals heterostructure

TL;DR

This study uses density functional theory to analyze a graphene/HfS2 heterostructure, demonstrating tunable Ohmic contact properties influenced by interlayer distance, strain, and electric fields, with implications for 2D device development.

Contribution

It provides a detailed theoretical analysis of how to tune contact types in graphene/HfS2 heterostructures using various physical parameters.

Findings

The interface is inherently n-type Ohmic.

Interlayer distance and strain significantly affect Schottky barrier height.

Applying a perpendicular electric field can switch contact from Ohmic to Schottky.

Abstract

With the use of density functional theory calculations and addition of van der Waals correction, the graphene/HfS$_2$ heterojunction is constructed, and its electronic properties are examined thoroughly. This interface is determined as $n$-type Ohmic and the impacts of different amounts of interlayer distance and strain on the contact are shown using Schottky barrier height and electron injection efficiency. Dipole moment and workfunction of the interface are also altered when subjected to change in these two categories. The transition between Ohmic to Schottky contact is also depicted to be possible by applying a perpendicular electric field, proving this to be yet another useful method for tuning different properties of this structure. The conclusions given in this paper can exert an immense amount of influence on the development of two-dimensional HfS$_2$ based devices in the future.