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Radiation effects of a 150 keV proton beam with various fluences on GaN-based quasi-vertical p–i–n diodes are investigated. For fundamental analysis, the electrical properties of P-GaN and N−-GaN separated from p–i–n diodes are also investigated. With the increase in the radiation-induced defect (e.g., VN and VGa) density, the carrier concentrations and mobilities of P-GaN and N−-GaN decrease significantly. Under the proton fluence of 1 × 1015 p/cm2, P-GaN has been transformed into highly resistive N-GaN, resulting in p–i–n diodes losing electrical characteristics of the PN junction. Meanwhile, the P-GaN Ohmic contact has been converted to Schottky contact. In addition, due to a large number of radiation-induced defects in P-GaN and N−-GaN, the reverse leakage current mechanism is revealed to change from space-charge-limited current conduction to Ohmic conduction. [ABSTRACT FROM AUTHOR]

Electrical and optical properties deterioration of P-GaN films under 150 keV proton irradiation were investigated. Through the Hall measurement method, as the irradiation fluence increasing, the carrier concentration of P-GaN films decreases from 1.23 $\times \,\,10^{{17}}$ to $-8.24\,\,\times \,\,10^{{16}}$ cm−3, and the carrier mobility change from 5.64 to 295.84 cm2/V/s. And through the circular transmission line model method, the sheet resistance and specific contact resistance for P-GaN films increased first and then decreased slightly under the proton irradiation. Radiation-induced $\text{V}_{\mathrm {N}}$ , $\text{Ga}_{\mathrm {i}}$ , $\text{V}_{\mathrm {Ga}}$ , and $\text{N}_{\mathrm {i}}$ were found to be responsible for the degradation of P-GaN films. It was confirmed that P-GaN has been transformed into N-GaN under the fluence of 1 $\times \,\,10^{15}$ p/cm2. The optical properties of the P-GaN films were characterized by examining changes in the photoluminescence spectrum. In addition, the electrical characteristics of Schottky barrier diode (SBD) and p-i-n diodes with the same structure (except for 0.5 $\mu \text{m}$ P-GaN of p-i-n diode) were used to study the effect of P-GaN degradation on electronic device performance. When P-GaN was transformed into N-GaN, p-i-n diodes lost the electrical characteristics of the p-n junction and the ${I}$ – ${V}$ curves of p-i-n diode are similar to that with SBD. [ABSTRACT FROM AUTHOR]