Impact of neutron irradiation on electronic carrier transport properties in Ga2O3 and comparison with proton irradiation effects

Abstract

The minority charge carrier transport in beta gallium oxide (-Ga2O3) before and after exposure to neutrons from a 241Am-Be source was studied. Cathodoluminescence (CL) spectroscopy and current–voltage (I-V) characteristics were used to study minority carrier behavior. High energy radiation affects minority carrier properties through the production of carrier traps that reduce the conductivity and mobility of the material. In this paper, we report the effects of neutron radiation in silicon-doped -Ga2O3, using rectifiers or transistors as the measurement platform. The thermal activation energy of the reference (non-irradiated) sample was 40.9 meV, which is ascribed to silicon-donors. CL measurements indicate a slightly indirect bandgap energy of 4.9 eV. Neutrons create disordered regions in -Ga2O3 rather than just point defects, resulting in the lowest carrier removal rate because of the lowest average non-ionizing energy loss. The neutron irradiation caused an increase in reverse bias leakage current in rectifiers and a carrier removal rate of 480 cm−1 but had little effect on reverse recovery switching time. Differences in CL spectra were observed between vertical and lateral device structures, emphasizing the importance of impurities and defects in the starting material. The neutron energies in the Am-Be source range up to 11 MeV, with an average energy between 4 and 5 MeV (Figure 1). We also contrasted neutron damage with the effects of irradiation with 10 MeV protons. Under 10 MeV proton irradiation, the thermal activation energies increase. This is attributable to high order defects and their influence on carrier lifetimes. The measurements show that -Ga2O3 is more resistant to radiation damage than other wide bandgap semiconductors due to its higher displacement threshold energy, which is inversely proportional to the lattice constant.