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-Ga 2 O 3 thin film on m-plane sapphire substrate was investigated by temperature-dependent Hall effect measurements (30–300 K). All films show dislocation density of about ~ 10 10 –10 11 cm −2 . In non-degenerate α-Ga 2 O 3 , an impurity-band effect is obvious in the low temperature region, and dislocation scattering is the dominant scattering mechanism. In contrast, in degenerate α-Ga 2 O 3 , 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-Ga 2 O 3 with high dislocation density is different from each other depending on whether α-Ga 2 O 3 is degenerate or non-degenerate. Finally, we estimate critical dislocation density for dislocation-insensitive mobility in α-Ga 2 O 3 on sapphire substrate, and indicate that dislocation densities below ~ 1 × 10 7 –1 × 10 8 cm −2 will be required for lightly doped drift layers in devices. Graphical Abstract