【Device Papers】Electrical stability of Cr₂O₃/β-Ga₂O₃ and NiOₓ/β-Ga₂O₃ heterojunction diodes

      Researchers from University of California Santa Barbara have published a dissertation titled " Electrical stability of Cr₂O₃/β-Ga₂O₃ and NiOₓ/β-Ga₂O₃ heterojunction diodes " in Physical Review Materials.

Abstract

      This work reports the electrical characteristics comparison study between Cr₂O₃ and NiOₓbased heterojunction diodes (HJD) on halide vapor phase epitaxy (HVPE) grown β-Ga₂O₃ epitaxial layers. Both as-fabricated Cr₂O₃ and NiOₓHJDs exhibited forward current density in a range of 130–150 A/cm² at 5 V with rectifying ratios >10¹⁰ and a reverse leakage current density at 10^-8 A/cm² at −5V. The differential specific on-resistance of Cr₂O₃ and NiOₓHJDs was 12.01mΩcm² and 12.05mΩcm², respectively. Breakdown voltages of Cr₂O₃ HJDs ranged from 1.4–1.9 kV and 1.5–2.3 kV for NiOₓ HJDs. Theoretical band alignment between Cr₂O₃ and β-Ga₂O₃ was calculated from first principles. The ambient exposed NiOₓ/HVPE β-Ga₂O₃ HJDs’ forward current density degraded after 10 days while that of Cr₂O₃/HVPE β-Ga₂O₃ HJDs’ remained nearly unchanged after the same amount of time. It was later confirmed that the ambient exposed sputtered NiOₓ sheet resistance (Rₛₕ) degradation gave rise to the reduction of the forward current density of the NiOₓ based HJDs, and water (H₂O) was qualitatively determined to be the agent attributed to the forward conduction degradation by measuring the Rₛₕ of NiOₓ-on-sapphire reference wafer after exposing it to different environments. The Cr₂O₃/HVPE β-Ga₂O₃ HJD also exhibited enhanced thermal stability compared to the NiOₓ/β-Ga₂O₃ heterostructures at elevated temperatures.

DOI：

https://doi.org/10.1103/wscr-3vxz