Pulsed fast reactor neutron irradiation effects in Si doped n-type β-Ga₂O₃

The effects of pulsed neutron irradiation on Si doped n-type β-Ga₂O₃ films grown by halide vapor phase epitaxy (HVPE) on bulk Sn doped n⁺ β-Ga₂O₃ substrates are reported. This irradiation leads to an almost linear increase with neutron fluence of the density of deep electron traps E2∗ (E_c - 0.74 eV), E3 (E_c - 1.05 eV), and E4 (E_c - 1.2 eV), with an introduction rate close to 0.4-0.6 cm^-1 while the density of the E2 traps (E_c - 0.8 eV) related to Fe was virtually unchanged. In addition, the increase in the density of deep traps with optical ionization threshold of 1.3 eV, 2.3 eV, and 3.1 eV with an introduction rate close to 0.8-2 cm^-1 was observed. The carrier removal rate under our conditions was 28 cm^-1. Neutron irradiation also led to a measurable decrease of the diffusion length of nonequilibrium charge carriers. The results are qualitatively similar to previous reports for proton and α-particle irradiation of HVPE β-Ga₂O₃. When comparing the findings with those described earlier for bulk neutron irradiated Ga₂O₃, we observe lower starting densities of electron and hole traps and lower introduction rates for these traps in the epitaxial structures. The carrier removal rates were comparable to those in bulk crystals.