NiGa2O4 Interfacial Layers in NiO/Ga2O3 Heterojunction Diodes at High Temperature: Article No. 173512

Kingsley Egbo, Emily Garrity, William Callahan, Chris Chae, Cheng-Wei Lee, Brooks Tellekamp, Jinwoo Hwang, Vladan Stevanovic, Andriy Zakutayev

Research output: Contribution to journalArticlepeer-review


NiO/Ga2O3 heterojunction diodes have attracted attention for high-power applications, but their high temperature performance and reliability remain underexplored. Here, we report the time evolution of the electrical properties in the widely studied p-NiO/n-Ga2O3 heterojunction diodes and formation of NiGa2O4 interfacial layers at high temperatures. Results of our thermal cycling experiment show an initial leakage current increase which stabilizes after sustained thermal load, due to reactions at the NiO-Ga2O3 interface. High-resolution TEM microstructure analysis of the devices after thermal cycling indicates that the NiO-Ga2O3 interface forms a ternary compound at high temperatures, and thermodynamic calculations suggest the formation of the spinel NiGa2O4 layer between NiO and Ga2O3. First-principles defect calculations find that NiGa2O4 shows low p-type intrinsic doping and hence can serve to limit electric field crowding at the interface. Vertical NiO/Ga2O3 diodes with intentionally grown ~5 nm thin spinel-type NiGa2O4 interfacial layers show an excellent device ON/OFF ratio of >1010 (+- 3 V), VON of ~1.9 V, and increased breakdown voltage of ~1.2 kV for an initial unoptimized diameter device. These p-n heterojunction diodes are promising for high-voltage, high temperature applications.
Original languageAmerican English
Number of pages7
JournalApplied Physics Letters
Issue number17
StatePublished - 2024

NREL Publication Number

  • NREL/JA-5K00-88442


  • density functional theory
  • electrical properties and parameters
  • high voltage diodes
  • interfacial instability
  • power electronics
  • pulsed laser deposition
  • semiconductor device fabrication
  • thermodynamic functions
  • thin film growth
  • transmission electron microscopy


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