Tin-assisted heteroepitaxial PLD-growth of κ-Ga2O3 thin films with high crystalline quality

• Published in: APL materials Vol. 7; no. 2; pp. 022516 - 022516-11
• Main Authors: Kneiß, M., Hassa, A., Splith, D., Sturm, C., von Wenckstern, H., Schultz, T., Koch, N., Lorenz, M., Grundmann, M.
• Format: Journal Article
• Language: English
• Published: AIP Publishing LLC 01-02-2019
• ISSN: 2166-532X; 2166-532X
• DOI: 10.1063/1.5054378

High-quality Ga2O3 thin films in the orthorhombic κ-phase are grown by pulsed-laser deposition using a tin containing target on c-sapphire, MgO(111), SrTiO3(111), and yttria-stabilized ZrO2(111) substrates. The structural quality of the layers is studied based on the growth parameters employing X-ray diffraction 2θ-ω scans, rocking curves, ϕ scans, and reciprocal space maps. Our layers exhibit superior crystalline properties in comparison to thin films deposited in the monoclinic β-phase at nominally identical growth parameters. Furthermore, the surface morphology is significantly improved and the root-mean-squared roughness of the layers was as low as ≈0.5 nm, on par with homoepitaxial β-Ga2O3 thin films in the literature. The orthorhombic structure of the thin films was evidenced, and the epitaxial relationships were determined for each kind of the substrate. A tin-enriched surface layer on our thin films measured by depth-resolved photoelectron spectroscopy suggests surfactant-mediated epitaxy as a possible growth mechanism. Thin films in the κ-phase are a promising alternative for β-Ga2O3 layers in electronic and optoelectronic device applications.