High-mobility rutile SnO₂ epitaxial films grown on (1(1)over-bar00) -Al₂O₃

Tin dioxide (SnO2) is a semiconductor with significant potential for use in the electronic industry, including sensors, transparent electrodes, and thin film transistors among other purposes. To realize these applications, the synthesis of high-quality thin films is a prerequisite. Here, we show the epitaxial growth of SnO2 films on (1 (1) over bar 00) alpha-Al2O3 (M-sapphire) by pulsed laser deposition method. The epitaxial relationship was clarified to be (001)[100]SnO2 || (1 (1) over bar 00)[0001] alpha-Al2O3 with 4-fold symmetry, consistent with that grown on (001) TiO2 single crystal. Orthorhombic distortion was absent, possibly owing to a combination of high strain relaxation due to a large lattice mismatch along [0001] alpha-Al2O3, coupled with a negligible mismatch- induced strain absence along [11 (2) over bar0] alpha-Al2O3. The mobility increases up to similar to 57 cm(2)V(-1) s(-1) with increasing film thickness while the density of states (DOS) effective mass keeps a constant around the theoretical value of similar to 0.3m(0). Furthermore, the trend of carrier concentration versus mobility is analogous to those of single crystal SnO2, thereby indicating the applicability of M-sapphire substrates in facilitating the epitaxial growth of high-quality SnO2 films. (c) 2023 The Ceramic Society of Japan. All rights reserved.