Light-enhanced gating effect at the interface of oxide heterostructure

TL;DR

This study demonstrates a significant enhancement of photoresponse at the LaVO3-SrTiO3 interface under combined light and negative gate bias, revealing an intrinsic mechanism involving band filling and electron interactions, distinct from oxygen vacancy migration.

Contribution

It uncovers an intrinsic light-enhanced gating effect at the oxide heterostructure interface, emphasizing the interplay of electronic interactions and electric fields rather than defect migration.

Findings

Enhanced photoresponse under light and negative gate bias

Insensitivity to light under positive gate bias

Intrinsic mechanism involving band filling and electron interactions

Abstract

In semiconducting materials, electrostatic gating and light illumination are widely used stimuli to tune the electronic properties of the system. Here, we show a significant enhancement of photoresponse at the conducting interface of LaVO3-SrTiO3 under the simultaneous application of light and negative gate bias voltage, in comparison to their individual application. On the other hand, the LaVO3-SrTiO3 interface remains largely insensitive to light illumination, when a positive gate bias voltage is applied. Our X-ray diffractometer, Raman spectroscopy and photoemission measurements show that unlike the LaAlO3-SrTiO3 interface, migration of oxygen vacancies is not the prime mechanism for the enhanced photoresponse. Rather, we suggest that the photoresponse of our system is intrinsic and this intrinsic mechanism is a complex interplay between band filling, electric field at the interface, strong electron interaction due to mottness of LaVO3 and modification of conducting channel width.