Activation energy of silicon diffusion in gallium oxide: Roles of the mediating defects charge states and phase modification

摘要

Silicon (Si) is an efficient n-type dopant in gallium oxide (Ga_2O_3)-an ultra-wide bandgap semiconductor promising in a number of applications. However, in spite of the technological importance for device fabrication, the activation energy for Si diffusion in Ga_2O_3 is missing in the literature. In the present work, we do such measurements in ion implanted monoclinic β-Ga_2O_3 samples employing anneals in air ambient, also admitting the influence of potential ion beam induced phase modifications on diffusion. Importantly, we show that Si diffusion in β-Ga_2O_3 fits with the concentration dependent diffusion model, involving neutral and single negatively charged point defects to mediate the process; so that we assumed gallium vacancies in the corresponding charge states to assist Si diffusion in β-Ga_2O_3 with activation energies of 3.2 ± 0.3 and 5.4 ± 0.4 eV, respectively. Moreover, we also found that a preexisting phase modified surface layer efficiently suppressed Si diffusion in β-Ga_2O_3 for temperatures up to 1000 °C.