Effect of Si or Mg co-doping on the thermally stimulated conductivity of β-Ga2O3: Mn ceramics in the temperature range 100–500 K

Unintentionally doped (UID), Mn-doped, as well as co-doped with Si or Mg, polycrystalline β-Ga2O3 ceramics were synthesized by a high-temperature solid-state reaction technique. Thermally stimulated current (TSC) measurements were carried out after UV filling of traps at 100 K, followed by heating from 100 to 500 K under an applied electric field. The UID β-Ga2O3 exhibits a pronounced low-temperature TSC maximum near 130 K and a set of higher-temperature maxima that can be decomposed into peaks in the 290–385 K range, consistent with previously reported E1–E3-type electron traps, together with additional peaks above 430 K. The introduction of Mn significantly increases the resistivity and suppresses trap-related transport of charge carriers. In particular, the photocurrent at 100 K decreases by several orders of magnitude compared to UID samples, and the low-temperature (100–200 K) TSC maxima disappear. This indicates a substantial reduction of the effective electron lifetime/photoconductive gain due to Mn-related recombination channels. Si co-doping partially restores photocurrent and TSC response, consistent with its role as a shallow donor that elevates the Fermi level and increases free-electron density. Mg co-doping enhances high-temperature trap contributions associated with oxygen vacancy-related defects while maintaining high resistivity. The combined TSC and dark-current analysis demonstrates that Mn-based doping, coupled with strategic Si/Mg co-doping, allows the controlled suppression or redistribution of trap states and carrier lifetime in β-Ga2O3, providing a pathway to engineer high-resistance materials for power and UV/optoelectronic applications.