【Epitaxy Papers】Growth of nitrogen-doped (010) β-Ga₂O₃ by plasma-assisted molecular beam epitaxy using an O₂/N₂ gas mixture

      Researchers from the University of California have published a dissertation titled "Growth of nitrogen-doped (010) β-Ga₂O₃ by plasma-assisted molecular beam epitaxy using an O₂/N₂ gas mixture" in Applied Physics Letters.

Abstract

      In this study, we report on the intentional nitrogen doping of plasma-assisted MBE (PAMBE)-grown (010) β-Ga₂O₃ films by generating the growth plasma with an O₂ and N₂ gas mixture. A nitrogen doping range of 1.3 × 10¹⁸ to 4.5 × 10¹⁹ cm⁻³ was achieved. The nitrogen doping profiles have top-hat shapes with sharp turn-on and turn-off. Nitrogen doping was found to have a negligible impact on surface morphology. Nitrogen incorporation was unaffected by gallium flux and growth temperatures over a large growth window. An incorporation dependence on plasma power and total gas flow rate was observed. This was attributed to the N₂ triple bond strength compared to the O₂ double bond strength, which makes N₂ harder to crack in the plasma source. Increasing the plasma power from 140 to 230 W increased nitrogen incorporation by 1.6×, while increasing the total gas flow rate from 0.8 to 2.0 sccm decreased incorporation by 3.2×. The compensation effect of nitrogen was verified by characterizing effective carrier concentration in conducting tin and nitrogen co-doped films. A 2.1 V built-in voltage was extracted from a nitrogen-doped, n⁻ junction device using CV measurements. The device was found to exhibit rectifying behavior with a 100 A/cm² current density at 2.9 V. The junction demonstrated here can play a key role in field management and electrostatic engineering for β-Ga₂O₃-based power devices. Overall, the controllability of PAMBE nitrogen doping and the properties of nitrogen-doped films suggest PAMBE-grown, nitrogen-doped layers have promising power device applications.

DOI：

https://doi.org/10.1063/5.0250037