Tetravalent element doping of β-Ga₂O₃ films grown by pulsed electron deposition technique

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 κ- 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.