Hole transport analysis in N-polar p-GaN

The transport-limiting scattering mechanisms in N-polar p-GaN were identified over a wide range of temperatures (220–770 K), Mg doping concentrations (3 × 1018–4 × 1019 cm−3), and V/III ratios (100–8000). Temperature-dependent Hall measurements, combined with a charge balance model, were employed to extract the acceptor (NA) and donor (ND) concentrations. These values enabled the determination of the temperature-dependent Hall factor (rH), allowing the conversion of the measured Hall mobility (μHall) to drift mobility (μdrift). The experimental drift mobility was then fitted using a mobility model, which incorporates six scattering mechanisms, including coulomb scattering by charged dislocation lines. The model identified charged dislocation scattering as the transport-limiting scattering mechanism at both room and low temperatures. The origin of coulomb scattering—donor-like traps along threading edge dislocations—was attributed to charged nitrogen vacancy-related defects [(VN−nMgGa)3−n, where n = 0, 1, or 2], with their concentration controllable through [Mg] and the nitrogen chemical potential (i.e., V/III ratio).