Tetravalent Element Doping of β-Ga₂O₃ Films Grown by Pulsed Electron Deposition Technique

Abstract

The Pulsed Electron Deposition (PED) technique was exploited to explore n-type doping of β-Ga₂O₃ thin films. Layers were deposited on (0001) sapphire at low-temperature (500°C), using homemade targets including variable amounts of Sn, Ge and Zr. The undoped films show a pure β-Ga₂O₃ phase with high crystallinity and an insulating nature, reporting resistivity values higher than 10⁷ Ω cm. The introduction of Sn leads to the formation of films including both |- and β-Ga₂O₃, with an electrical resistivity of approximately 10⁵ Ω cm. The doping with Ge results in the formation of high-quality β-Ga₂O₃ layers, but with high resistivity (~10⁶ Ω cm). Zr is identified as the most effective dopant, resulting in the formation of single-phase epitaxial β-Ga₂O₃ films with low resistivity (~5 Ω cm). The present study indicates the PED technique to be an effective method for the deposition of good quality epitaxial β-Ga₂O₃ films at low temperatures, allowing the simple exploration of doping without the need for complex or toxic precursors.