The effects of sputtering powers on the structural, optical and electrical properties of β-Ga2O3 thin films prepared by magnetron sputtering

Abstract

$\beta$-Ga${}_2$O${}_3$ exhibits promising electrical properties and stability for power electronics and UV detectors, yet achieving effective p-type doping remains challenging. This study investigates Bi and Cu-doped $\beta$-Ga${}_2$O${}_3$ thin films grown via magnetron sputtering on sapphire, focusing on sputtering power effects post-annealing. Structural and optical analyses (X-ray diffraction, XRD; X-ray photoelectron spectroscopy, XPS; scanning electron microscopy, SEM; energy-dispersive spectroscopy, EDS; Raman spectroscopy, photoluminescence, and transmission spectroscopy) reveal a reduced bandgap from 4.97 eV to 3.80 eV after doping, aligning with theoretical predictions that Bi${}_2$O${}_3$ alloying elevates the valence band. Room-temperature photoluminescence identified two blue–green emission bands. Hall measurements confirmed weak p-type conductivity at the 1000 G field, with resistivity 1.49 × 10¹¹ $\Omega$ cm, Hall coefficient 4.22 × 10¹³ cm${}^2$/C, mobility 334.95 cm${}^2$V⁻¹s⁻¹, and carrier density 1.48 × 10${}^5$ cm⁻². These results advance p-type $\beta$-Ga${}_2$O${}_3$ research, demonstrating dual-acceptor doping as a viable pathway for modulating optoelectronic properties.