Preparation and evaluation of alexandrite, forsterite, and topaz substrates for the epitaxial growth of rutile oxides

TL;DR

This study develops and evaluates new single-crystalline substrates for epitaxial growth of rutile oxides, enabling advanced electronic applications through improved thin film synthesis.

Contribution

It introduces three novel substrates with atomically smooth surfaces suitable for rutile oxide epitaxy, expanding options for strain engineering and physical property exploration.

Findings

Successful heteroepitaxy of rutile TiO2, VO2, NbO2, and RuO2 on new substrates

BeAl2O4 shows high thermal and chemical stability

New substrates facilitate strain engineering of rutile oxides

Abstract

Metal-insulator transitions and superconductivity in rutile-structured oxides hold promise for advanced electronic applications, yet their thin film synthesis is severely hindered by limited substrate options. Here, we present three single- crystalline substrates, BeAl2O4, Mg2SiO4, and Al2SiO4(F,OH)2, prepared via optimized thermal and chemical treatments to achieve atomically smooth surfaces suitable for epitaxial growth. Atomic force microscopy confirms atomic step-and-terrace surface morphologies, and oxide molecular-beam epitaxy growth on these substrates demonstrates successful heteroepitaxy of rutile TiO2, VO2, NbO2, and RuO2 films. Among these unconventional substrates, BeAl2O4 exhibits exceptional thermal and chemical stability, making it a versatile substrate candidate. These findings introduce new substrate platforms that facilitate strain engineering and exploration of rutile oxide thin films, potentially advancing the study of their strain-dependent physical properties.