Effects of post-deposition annealing temperatures in argon ambient on structural, optical, and electrical characteristics of RF magnetron sputtered gallium oxide films

Abstract

Different post-deposition annealing temperatures were carried out in argon ambient to investigate the corresponding effects onto structural, morphological, optical, and electrical characteristics of RF magnetron sputtered gallium oxide (Ga2O3) films. Cubic phase of γ-Ga2O3 was transformed to mixed phases of cubic and monoclinic phases of β-Ga2O3 as the temperature was increased from 400 to 800 °C before became fully β-Ga2O3 phases at 1000 °C. Oxygen vacancies and oxygen interstitials were formed, generating deep energy levels in band gap of the Ga2O3 films. Findings revealed the acquisition of the highest current density in the Ga2O3 film annealed at 400 °C as a consequence of the highest density (J) of dislocation and oxygen vacancies in the film. Nonetheless, the formation of a thicker interfacial layer and location of oxygen vacancies in the film annealed at 1000 °C have caused minute increase in the J surpassing that of 800 °C at a gate voltage greater than 15 V.

Keywords

• Gallium oxide
• Polycrystalline
• Argon
• Annealing
• Wide bandgap
• Critical electric field