Evolution of Frenkel defect pairs in β-Ga2O3 thin film with the introduction of oxygen and its application in GaN-based ultraviolet light-emitting diode

In this work, beta-Ga2O3 thin films were deposited by radio frequency (RF) magnetron sputtering technique. The effect of oxygen-argon flow ratio (OAFR) on the formation of Frenkel defect pairs was systematically analyzed. The Frenkel defect pairs would become abundant when the OAFR was 25:25 sccm, resulting in a severe damage in crystalline quality and an increase in the density of disorder. With the further increase of OAFR, Frenkel defect pairs would dramatically decrease or even vanish due to the significant reduction of oxygen vacancies (V0). Immediately after that, on the basis of avoiding the influence of Frenkel defect pairs inside the beta-Ga2O3 films to the devices, the p-NiO/i-Ga2O3/n-GaN diode was fabricated from the as-prepared high-quality beta-Ga2O3 film after post-deposition annealing as the electron-blocking layer. Subsequently, its electrical characteristics were investigated in detail which exhibited excellent rectification characteristics under all test temperatures. Correspondingly, the device achieved electroluminescence (EL) with a dominant sharp emission peak in the ultraviolet range (similar to 375 nm). In the end, the energy band diagram was used for in-depth analysis of the EL mechanism.

Automated summary

In this work, beta-Ga2O3 thin films were deposited using RF magnetron sputtering technique and the effect of oxygen-argon flow ratio (OAFR) on Frenkel defect pairs formation was analyzed. Frenkel defect pairs increased when OAFR was 25:25 sccm, leading to damage in crystalline quality and increased disorder density. Further increase in OAFR caused a dramatic decrease or disappearance of Frenkel defect pairs due to reduction in oxygen vacancies (V0). A p-NiO/i-Ga2O3/n-GaN diode was fabricated from the high-quality beta-Ga2O3 film after annealing to avoid the influence of Frenkel defect pairs on devices, exhibiting excellent rectification characteristics and electroluminescence in the ultraviolet range (similar to 375 nm).