Patterning of high mobility electron gases at complex oxide interfaces

TL;DR

This paper introduces a novel patterning method for complex oxide interfaces that preserves high electron mobility, enabling advanced quantum electronic studies and achieving some of the highest mobilities reported.

Contribution

It presents an effective patterning strategy using selective wet etching that maintains high electron mobility at oxide interfaces, a significant advancement over previous methods.

Findings

Patterned interfaces exhibit electron mobilities up to ~8,700 cm²/Vs at 2 K.

The method preserves high mobility while enabling precise patterning.

Achieves among the highest reported mobilities for patterned complex oxide interfaces.

Abstract

Oxide interfaces provide an opportunity for electronics. However, patterning of electron gases at complex oxide interfaces is challenging. In particular, patterning of complex oxides while preserving a high electron mobility remains underexplored and inhibits the study of quantum mechanical effects where extended electron mean free paths are paramount. This letter presents an effective patterning strategy of both the amorphous-LaAlO$_3$/SrTiO$_3$ (a-LAO/STO) and modulation-doped amorphous- LaAlO$_3$/La$_{7/8}$Sr$_{1/8}$MnO$_3$/SrTiO$_3$ (a-LAO/LSM/STO) oxide interfaces. Our patterning is based on selective wet etching of amorphous-LSM (a-LSM) thin films which acts as a hard mask during subsequent depositions. Strikingly, the patterned modulation-doped interface shows electron mobilities up to ~8,700 cm$^2$/Vs at 2 K, which is among the highest reported values for patterned conducting complex oxide interfaces that usually are ~1,000 cm$^2$/Vs at 2 K.