Nitrogen doping of metal-organic chemical vapor deposition β-Ga2O3 using nitric oxide

We report on the use of nitric oxide (NO) diluted in nitrogen as a nitrogen dopant source for β-Ga2O3 grown by metal-organic chemical vapor deposition. The effects of the NO/N2 flow rate, Ga precursor molar flow rate, and substrate temperature on nitrogen incorporation, doping controllability, and film growth rate were systematically investigated. Introducing small NO flows with O2 increased film growth rates by ∼1.8–3.2× and enabled controllable nitrogen incorporation in films grown using triethylgallium and trimethylgallium precursors. Secondary ion mass spectrometry revealed a strong dependence of nitrogen incorporation on the NO flow rate, gallium supply, and substrate temperature. Nitrogen concentrations up to 6.5 × 1018 cm−3 were achieved, while NO/N2 doping yielded substantially lower hydrogen incorporation, with N/H ratios up to ∼28. The resulting films exhibited excellent crystallinity, smooth morphology, and thermally activated conduction with activation energies ranging from ∼27 to 509 meV, depending on nitrogen concentration. These results establish NO as an alternative nitrogen source that enables controlled N doping with minimal hydrogen incorporation—offering a practical route for realizing semi-insulating β-Ga2O3 layers suitable for high-power electronic applications.