Effect of dislocations and impurities on carrier transport in α-Ga2O3 on m-plane sapphire substrate

Carrier transport mechanism in Si-doped n-type α-Ga2O3thin film on m-plane sapphire substrate was investigated by temperature-dependent Hall effect measurements (30–300 K). All films show dislocation density of about ~ 1010–1011cm−2. In non-degenerate α-Ga2O3, an impurity-band effect is obvious in the low temperature region, and dislocation scattering is the dominant scattering mechanism. In contrast, in degenerate α-Ga2O3, although the dislocation density is comparable to the non-degenerate one, the mobility is dominated by ionized impurity scattering, due to the heavy screening of charged dislocations. The analysis indicates that the carrier transport mechanism in α-Ga2O3with high dislocation density is different from each other depending on whether α-Ga2O3is degenerate or non-degenerate. Finally, we estimate critical dislocation density for dislocation-insensitive mobility in α-Ga2O3on sapphire substrate, and indicate that dislocation densities below ~ 1 × 107–1 × 108cm−2will be required for lightly doped drift layers in devices.Graphical Abstract