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As a viable alternative to the challenging fabrication of robust β-Ga2O3 p–n homojunctions, this study investigates the variable-temperature photocurrent of p-NiO/n-Ga2O3 heterojunction photodiodes under zero-bias conditions. The device's built-in electric field is utilized to achieve efficient separation of non-equilibrium photogenerated carriers. To support the experimental findings, computer simulations of the electric field distribution at the heterointerface were performed and correlated with experimental current–voltage and capacitance–voltage measurements. The photocurrent measurements confirm the narrowing of the n-Ga2O3 bandgap with increasing temperature, consistent with predictions from the Varshni equation. The observed decrease in photocurrent amplitude at lower temperatures is attributed to bandgap widening, which results in a smaller number of non-equilibrium carriers generated by the excitation wavelength. 

This study investigates minority electron diffusion length and carrier recombination phenomena in p-type 300 nm-thick Ga2O3 films homoepitaxially grown over a (001) tin-doped β-Ga2O3 conductive substrate. This research is novel due to its systematic and near-simultaneous measurements in the top layer of a p-Ga2O3/n-Ga2O3 structure using independent electron beam-induced current and cathodoluminescence techniques. Previous work primarily focused on heteroepitaxial architectures or gallium oxide grown over insulating substrates of the same material. In this work, the activation energies related to point defects in gallium oxide were extracted from temperature-dependent incremental electron beam irradiation experiments to gain insight into the defect landscape and its influence on minority carrier transport and recombination dynamics. 

Abstract Lateral Schottky or heterojunction rectifiers were irradiated with 10 MeV protons and neutrons. For proton irradiation, the forward current of both types of rectifiers decreased by approximately an order of magnitude, with a corresponding increase in on-state resistance. The resultant on/off ratio improved after irradiation because of the larger decrease in reverse current compared to forward current. Both types of rectifiers displayed a shift in forward current and RON curves to lower voltages after irradiation. This could be due to defects created by neutron irradiation introducing deep energy levels within the bandgap of AlN. These deep levels can trap charge carriers, reducing their mobility and increasing the on-state resistance. Transmission electron microscopy showed disorder created at the AlN/NiO interface by neutron irradiation. TCAD simulation was used to study the effects of irradiation with both protons and neutrons. The results confirmed that the irradiation caused a significant reduction in electron concentration and a small increase in the recombination rate. Neutron irradiation can also introduce interface states at the metal or oxide-semiconductor junction of the rectifier. These interface states can modify the effective Schottky barrier height, affecting the forward voltage drop and on-state resistance.