Patterning of two-dimensional electron systems in SrTiO3 based heterostructures using a CeO2 template

TL;DR

This paper introduces a CeO2-based patterning method for SrTiO3 heterostructures that preserves interfacial conductance, enabling detailed study of anisotropic electron transport at low temperatures.

Contribution

A novel CeO2 template-based patterning technique for SrTiO3 heterostructures that avoids degradation of interfacial conductance during microfabrication.

Findings

Successful fabrication of microbridges with preserved conductance

Observation of significant anisotropic transport below 30 K

Anisotropy mainly due to impurity/defect scattering

Abstract

Two-dimensional electron systems found at the interface of SrTiO3-based oxide heterostructures often display anisotropic electric transport whose origin is currently under debate. To characterize transport along specific crystallographic directions, we developed a hard-mask patterning routine based on an amorphous CeO2 template layer. The technique allows preparing well-defined microbridges by conventional ultraviolet photolithography which, in comparison to standard techniques such as ion- or wet-chemical etching, does not induce any degradation of interfacial conductance. The patterning scheme is described in details and the successful production of microbridges based on amorphous Al2O3-SrTiO3 heterostructures is demonstrated. Significant anisotropic transport is observed for T < 30 K which is mainly related to impurity/defect scattering of charge carriers in these heterostructures.