Growth of polycrystalline gallium oxide films in stagnant oxygen stream ambient

Structural, morphological, optical, and electrical characteristics of polycrystalline gallium oxide (Ga2O3) films subjected to different post-deposition annealing temperatures (400 -1000 degrees C) in a stagnant oxygen stream ambient were systematically studied. The transformation from gamma-Ga2O3 to beta-Ga2O3 phase was perceived as the temperature was enhanced to/beyond 600 degrees C. An alleviation of oxygen related defects in Ga2O3 films was supported through a reduction in full-width half maximum (FWHM) for beta-Ga2O3 peak oriented in (400) plane and dislocation density (delta), as well as an improvement in crystallinity when a higher temperature was employed. Nonetheless, the employment of the highest temperature has contributed to an excessive diffusion of oxygen anions to the interface contributing to the formation of a well-defined interfacial layer. Besides, the oxygen ions were also occupying the interstitial sites of Ga2O3 lattice at 1000 degrees C contributing to a sudden contraction of indirect band gap (E-g). These detrimental effects have suggested that 1000 degrees C was not a suitable annealing temperature for Ga2O3 films. Of these investigated films, Ga2O3 film annealed at 800 degrees C has demonstrated a better leakage current density characteristic than that of 400 and 600 degrees C due to acquisition of the lowest delta, the smallest FWHM, as well as the largest direct and indirect E-g. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

The study systematically investigated the effects of post-deposition annealing at different temperatures on polycrystalline gallium oxide films, showing improvements in structural, morphological, optical, and electrical characteristics as temperature increased up to a certain point. However, excessive annealing temperature resulted in detrimental effects such as interfacial layer formation due to excessive oxygen anion diffusion and sudden contraction of indirect band gap, suggesting that 1000 degrees C was not a suitable annealing temperature for Ga2O3 films. An optimized annealing temperature of 800 degrees C demonstrated the best leakage current density characteristic due to improved crystallinity and the smallest FWHM.