Off-stoichiometry engineering of the electrical and optical properties of SrNbO$_3$ by oxide molecular beam epitaxy

TL;DR

This paper demonstrates that engineering off-stoichiometry in SrNbO$_3$ via oxide molecular beam epitaxy can effectively tune its optical and electrical properties, expanding its potential for transparent electronics without additional element doping.

Contribution

It introduces a novel off-stoichiometry engineering method to modify SrNbO$_3$ properties, surpassing thermodynamic limitations of phase stability and broadening application possibilities.

Findings

Controlled Sr deficiency shifts plasma edge into near-infrared.

Epitaxial growth enables property tuning beyond thermodynamic constraints.

Vacancy sites act as virtual substitutional elements for property modification.

Abstract

The highly conducting and transparent inorganic perovskites SrBO$_3$ with V, Nb, Mo, and their mixtures at the B-site have recently attracted the attention of the oxide electronics community as novel alternative transparent conducting oxides. For different applications from solar cells to transparent electronics, it is desirable to tune the optical transmission window in the ultraviolet (UV), visible and infrared (IR) range. The conventional approach is substitutional design at the A- and/or B-site. Here, we suggest a method by engineering the off-stoichiometry of the perovskite, opening new pathways to broaden the range of applications without adding additional elements. For oxide molecular beam epitaxy grown SrNbO$_3$ on GdScO$_3$ substrates, we show that controlled Sr deficiency shifts the plasma edge from about 2 eV in the visible range into the near-infrared region, 1.37 eV (similar to stoichiometric SrVO$_3$). Here, epitaxial growth allows going beyond the limitations of phase stability set by thermodynamics. The suggested approach opens a new design toolbox by including controlled vacancy sites as quasi-substitutional virtual elements.