Insight into the High Hole Concentration of p-Type Ga2O3 via In Situ Nitrogen Doping

The unclear p-type conduction mechanism and lack of reliable p-type Ga2O3 severely hinder Ga2O3-based high-voltage electronics. Here, we demonstrate in situ nitrogen (N) doping via metal-organic chemical vapor deposition homoepitaxy using N2O as oxygen source and acceptor dopant. Structural and compositional analyses confirm efficient N incorporation (favored by N-Ga bonding) compensating residual Si/H donors without compromising crystallinity. The Ga2O3:N epilayers achieve excellent p-type performance: 1.04 × 1018 cm-3 hole concentration, 0.47 cm2 V-1 s-1 mobility at room temperature, and 0.168 eV activation energy. A completely new insight into the p-type conduction mechanism in Ga2O3 is introduced, focusing on the crystallographic visualization of acceptors (N2-) and holes (O-), as well as the hole excitation process. It is suggested that careful suppression of the donor compensation effect and precise control of the N chemical potential, which leads to the fabrication of trace O- species solid-dissolved within Ga2O3, are essential for achieving high-hole-concentration p-type conduction in oxides.