Electrical characterization of Si-doped n-type α-Ga2O3 on sapphire substrates

Issues on tin (Sn) doping in the mist chemical vapor deposition of alpha-Ga2O3 was attributed to conversion of ionization states of Sn from Sn4+ to Sn2+ and/or out-diffusion of Sn after thermal annealing, resulting in highly resistive films. Silicon (Si) doping, instead, was succeeded by the use of a novel doping source of chloro-(3-cyanopropyl)-dimethylsilane [ClSi(CH3)(2)((CH2)(2)CN)]. Si was uniformly incorporated in the alpha-Ga2O3 films and the electrical properties were stable even after the thermal annealing. The activation ratio as donors was nearly 100%. The carrier (electron) concentration was controlled to the level of 10(18) cm(-3) by the [Si]/[Ga] ratio in the source solution. The maximum mobility was 31.5 cm(2)/V s, in contrast to 24 cm(2)/V s with Sn doping, suggesting advantage of Si doping. However, the reduction in dislocation defects in the alpha-Ga2O3 films formed owing to heteroepitaxy on sapphire was suggested to be the important subject to be considered in the next stage.