# Negative Fermi-level Pinning Effect of Metal/n-GaAs(001) Junction with Graphene Interlayer

## TL;DR

This paper demonstrates that a graphene interlayer can induce a negative Fermi-level pinning effect at metal/n-GaAs contacts, enabling control over contact types and preserving low interface-trap density.

## Contribution

It reveals that graphene interlayers can invert the effective work-function of metals, facilitating both Schottky and Ohmic contacts on low surface-state GaAs.

## Key findings

- Negative Fermi-level pinning observed with graphene interlayer.
- Graphene prevents atomic intermixing at the interface.
- Schottky barrier decreases with increasing metal work-function.

## Abstract

It is demonstrated that the electric dipole layer due to the overlapping of electron wavefunctions at metal/graphene contact results in negative Fermi-level pinning effect on the region of GaAs surface with low interface-trap density in metal/graphene/n-GaAs(001) junction. The graphene interlayer takes a role of diffusion barrier preventing the atomic intermixing at interface and preserving the low interface-trap density region. The negative Fermi-level pinning effect is supported by the Schottky barrier decreasing as metal work-function increasing. Our work shows that the graphene interlayer can invert the effective work-function of metal between $high$ and $low$, making it possible to form both Schottky and Ohmic-like contacts with identical (particularly $high$ work-function) metal electrodes on a semiconductor substrate possessing low surface-state density.