Insight into the High Hole Concentration of p-Type Ga 2 O 3 via In Situ Nitrogen Doping

The unclear p-type conduction mechanism and lack of reliable p-type Ga 2 O 3 severely hinder Ga 2 O 3 -based high-voltage electronics. Here, we demonstrate in situ nitrogen (N) doping via metal–organic chemical vapor deposition homoepitaxy using N 2 O 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 Ga 2 O 3:N epilayers achieve excellent p-type performance: 1.04 × 10 18 cm –3 hole concentration, 0.47 cm 2 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 Ga 2 O 3 is introduced, focusing on the crystallographic visualization of acceptors (N 2– ) 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 Ga 2 O 3, are essential for achieving high-hole-concentration p-type conduction in oxides.