Investigations of the growth and physical characteristics of ZNF2-DOPED GA2O3 thin films

Abstract

This study began by preparing gallium oxide (Ga2O3) doped with zinc fluoride (ZnF2) and manufacturing a target material. Subsequently, electron beam (e-beam) deposition was employed to coat silicon substrates with the prepared material. Different heat treatment conditions were applied to the deposited films, followed by material and electrical property analyses. The investigation explored the impact of pre-sintering Ga2O3 at 950°C to transform it into a more stable [Formula: see text]-phase. For comparative purposes, some samples underwent annealing at 600°C in a nitrogen–hydrogen (95% N[Formula: see text] H2, abbreviated as N[Formula: see text]) mixed gas, which was used as a reduction atmosphere, to increase oxygen vacancies in the ZnF2-doped Ga2O3 thin films and consequently enhance their conductivity. The deposited ZnF2-doped Ga2O3 thin films initially exhibited an amorphous phase, with diffraction peaks appearing only after a 600°C annealing process. Pre-sintering Ga2O3 powder at 950°C promoted the emergence of the [Formula: see text]-phase, and the bandgap value increased after annealing. Measurements using B1500A revealed that sintering and annealing ZnF2-doped Ga2O3 thin films were essential steps to enhance their conductivity. X-ray photoelectron spectroscopy (XPS) further confirmed a significant correlation between the conductivity variation and the concentration of oxygen vacancies. Additionally, it was observed that the use of an N[Formula: see text] mixed gas further increased the presence of oxygen vacancies in the films. The results of this study provide an important method to make Ga2O3 thin films with conductivity, which can be utilized in the fabrication of Ga2O3 thin-film-based semiconductor devices in the future.