Influence of interface dipole layers on the performance of graphene field effect transistors

TL;DR

This study investigates how interface dipole layers at the graphene-SiO2 interface influence the electronic properties and performance of graphene field-effect transistors, highlighting the role of surface chemistry and electrostatic effects.

Contribution

It provides detailed band alignment analysis and links interface dipoles to GFET performance, offering insights for device optimization.

Findings

Hydrophilic SiO2 surfaces modulate graphene's electronic properties.

Interface dipoles are crucial in determining GFET performance.

Hysteresis in resistance is caused by dipole layer reversal under gate voltage.

Abstract

The linear band dispersion of graphene's bands near the Fermi level gives rise to its unique electronic properties, such as a giant carrier mobility, and this has triggered extensive research in applications, such as graphene field-effect transistors (GFETs). However, GFETs generally exhibit a device performance much inferior compared to the expected one. This has been attributed to a strong dependence of the electronic properties of graphene on the surrounding interfaces. Here we study the interface between a graphene channel and SiO$_{2}$, and by means of photoelectron spectromicroscopy achieve a detailed determination of the course of band alignment at the interface. Our results show that the electronic properties of graphene are modulated by a hydrophilic SiO$_{2}$ surface, but not by a hydrophobic one. By combining photoelectron spectromicroscopy with GFET transport property characterization, we demonstrate that the presence of electrical dipoles in the interface, which reflects the SiO$_{2}$ surface electrochemistry, determines the GFET device performance. A hysteresis in the resistance vs. gate voltage as a function of polarity is ascribed to a reversal of the dipole layer by the gate voltage. These data pave the way for GFET device optimization.