In situ nitrogen doping of β-Ga₂O₃ during MOCVD homoepitaxy : A theoretical and experimental study

The precise control of acceptor doping concentrations in epilayers is critical for fabricating key β-Ga₂O₃-based power electronic structures, including current-blocking layers, p-type epilayers, and drift layers. Unintentional nitrogen (N) compensating dopants introduced by N₂O (a common oxygen precursor) during β-Ga₂O₃ metalorganic chemical vapor deposition growth significantly affects electrical properties. This study demonstrates that N concentration in epilayers is largely determined by growth temperature and surface adsorption efficiency. As the epitaxial temperature increases, the N doping concentration in the epilayer decreases. When the epitaxial temperature exceeds 1000 °C, the efficiency of N adsorption on β-Ga₂O₃ surfaces is influenced by both epitaxial parameters and substrate orientation. Modifying epitaxial parameters, especially by increasing chamber pressure, enhances the N concentration in β-Ga₂O₃ epilayers. Stronger N adsorption occurs on the (100)-plane compared to the (001)-plane epilayer; however, the (001)-plane epilayer allows better N concentration tuning through adjustments in parameters. First-principles calculations indicate that such observed differences in adsorption efficiency are attributable to variations in adsorption energies specific to each plane, coupled with competitive interactions between nitrogen (N) and oxygen (O) atoms during surface reactions. This study offers fundamental insights that advance the engineering of β-Ga₂O₃ homoepilayers for power electronics applications.