Au-Gated SrTiO3 Field-Effect Transistors with Large Electron Concentration and Current Modulation

TL;DR

This paper demonstrates Au-gated SrTiO3 MESFETs with record-high electron density modulation and current density, leveraging the high Schottky barrier and dielectric properties of SrTiO3.

Contribution

It introduces Au-gated MESFETs on SrTiO3 with unprecedented electron modulation and current density, surpassing previous SrTiO3 device performances.

Findings

Achieved ~1.6 x 10^14 cm^-2 electron density modulation.

Realized current densities up to ~68 mA/mm, 20 times higher than previous SrTiO3 MESFETs.

Identified the impact of interfacial layer and dielectric constant on device performance.

Abstract

We report the fabrication of low-leakage rectifying Pt and Au Schottky diodes and Au-gated metal-semiconductor field effect transistors (MESFETs) on n-type SrTiO3 thin films grown by hybrid molecular beam epitaxy. In agreement with previous studies, we find that compared to Pt, Au provides a higher Schottky barrier height with SrTiO3. As a result of the large dielectric constant of SrTiO3 and the large Schottky barrier height of Au, the Au-gated MESFETs are able to modulate ~1.6 x 1014 cm-2 electron density, the highest modulation yet achieved using metal gates in any material system. These MESFETs modulate current densities up to ~68 mA/mm, ~20x times larger than the best demonstrated SrTiO3 MESFETs. We also discuss the roles of the interfacial layer, and the field-dependent dielectric constant of SrTiO3 in increasing the pinch off voltage of the MESFET.