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Minority carrier diffusion length in undoped p-type gallium oxide was measured at various temperatures as a function of electron beam charge injection by electron beam-induced current technique in situ using a scanning electron microscope. The results demonstrate that charge injection into p-type β-gallium oxide leads to a significant linear increase in minority carrier diffusion length followed by its saturation. The effect was ascribed to trapping of non-equilibrium electrons (generated by a primary electron beam) on metastable native defect levels in the material, which in turn blocks recombination through these levels. While previous studies of the same material were focused on probing a non-equilibrium carrier recombination by purely optical means (cathodoluminescence), in this work, the impact of charge injection on minority carrier diffusion was investigated. The activation energy of ∼0.072 eV, obtained for the phenomenon of interest, is consistent with the involvement of Ga vacancy-related defects. 

It has recently been demonstrated that electron beam injection into p-type β-gallium oxide leads to a significant linear increase in minority carrier diffusion length with injection duration, followed by its saturation. The effect was ascribed to trapping of non-equilibrium electrons (generated by a primary electron beam) at meta-stable native defect levels in the material, which in turn blocks recombination through these levels. In this work, in contrast to previous studies, the effect of electron injection in p-type Ga2O3 was investigated using cathodoluminescence technique in situ in scanning electron microscope, thus providing insight into minority carrier lifetime behavior under electron beam irradiation. The activation energy of ∼0.3 eV, obtained for the phenomenon of interest, is consistent with the involvement of Ga vacancy-related defects. 

Electron beam-induced current in the temperature range from 304 to 404 K was employed to measure the minority carrier diffusion length in metal–organic chemical vapor deposition-grown p-Ga2O3 thin films with two different concentrations of majority carriers. The diffusion length of electrons exhibited a decrease with increasing temperature. In addition, the cathodoluminescence emission spectrum identified optical signatures of the acceptor levels associated with the VGa−–VO++ complex. The activation energies for the diffusion length decrease and quenching of cathodoluminescence emission with increasing temperature were ascribed to the thermal de-trapping of electrons from VGa−–VO++ defect complexes. 

Highly resistive undoped p-type gallium oxide samples were subjected to cumulative proton irradiation with energies ranging from 25 to 70 keV and doses in the 1.6 × 10¹⁴–3.6 × 10¹⁴cm⁻²range. Proton irradiation resulted in up to a factor of 2 reduction of minority electron diffusion length in the samples for temperatures between ∼ 300 and 400 K. Electron injection into the samples under test using a scanning electron microscope beam leads to pronounced elongation of diffusion length beyond the pre-irradiation values, thus demonstrating stable (days after injection) recovery of adverse radiation impact on minority carrier transport. The activation energy of 91 meV estimated from the temperature dependent diffusion length vs electron injection duration experiments is likely related to the local potential barrier height for native defects associated with the phenomenon of interest.