A new semiconducting perovskite alloy system made possible by gas-source molecular beam epitaxy

TL;DR

This paper reports the first epitaxial growth of a new semiconducting chalcogenide perovskite alloy system using gas-source molecular beam epitaxy, enabling tunable band gaps for optoelectronic applications.

Contribution

It introduces a novel alloy family of BaZrS$_{(3-y)}$Se$_y$ perovskites grown epitaxially, expanding the range of semiconductor materials available for optoelectronics.

Findings

Successful epitaxial growth of BaZrS$_{(3-y)}$Se$_y$ alloys

Band gap tunability from 1.9 to 1.4 eV with Se content

Films are environmentally stable and suitable for optoelectronic devices

Abstract

Optoelectronic technologies are based on families of semiconductor alloys. It is rare that a new semiconductor alloy family is developed to the point where epitaxial growth is possible; since the 1950s, this has happened approximately once per decade. Here we demonstrate epitaxial thin film growth of semiconducting chalcogenide perovskite alloys in the Ba-Zr-S-Se system by gas-source molecular beam epitaxy (MBE). We stabilize the full range y = 0 ... 3 of compositions BaZrS$_{(3-y)}$Se$_y$ in the perovskite structure, up to and including BaZrSe$_3$, by growing on BaZrS$_3$ epitaxial templates. The resulting films are environmentally stable and the direct band gap ($E_g$) varies strongly with Se content, as predicted by theory, covering the range $E_g$ = 1.9 ... 1.4 eV for $y$ = 0 ... 3. This creates possibilities for visible and near-infrared (VIS-NIR) optoelectronics, solid state lighting, and solar cells using chalcogenide perovskites.