【Device Papers】Oxygen vacancy control engineering in Ga₂O₃/4H-SiC Schottky rectifiers

      Researchers from the Kwangwoon University have published a dissertation titled "Oxygen vacancy control engineering in Ga₂O₃/4H-SiC Schottky rectifiers" in Applied Physics Letters.

Abstract

      This work investigates oxygen vacancy (V_O) engineering in Ga₂O₃/4H-SiC heterojunction Schottky barrier diodes (HJ-SBDs) through post-deposition O₂ annealing to enhance breakdown performance. Aerosol-deposited Ga₂O₃ films (∼900 nm) on n-type 4H-SiC substrates were annealed in O₂ ambient at 800, 900, and 1000 °C. The oxygen deficiency ratio was found to decrease substantially from 48.5% to 23.4% as the annealing temperature increased to 900 °C, accompanied by a ninefold reduction in deep trap density from 7.3 × 10¹³ to 8.1 × 10¹² cm⁻³. The as-deposited devices exhibit dual conduction mechanisms of Schottky emission and Poole–Frenkel emission, with breakdown voltage limited to 960 V due to high V_O concentration. The reverse leakage current in O₂-annealed devices was found to be governed by variable range hopping conduction under high electric fields. At optimal annealing conditions of 900 °C, the breakdown voltage increases remarkably from 960 to ≥3000 V. The enhanced breakdown results from the significant reduction of V_O-related traps that dominate the leakage mechanisms in as-deposited Ga₂O₃ films. Our V_O-engineered Ga₂O₃/4H-SiC HJ-SBDs demonstrate superior breakdown and thermal stability, showing the great potential of defect engineering for high-voltage power applications.

DOI：

https://doi.org/10.1063/5.0293743