Evolution and Mechanism of P-GaN Films Under Proton Irradiation and Its Influence on Electronic Device

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 cm ² /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/cm ² . 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.