Effect of gamma irradiation on AlInGaN/AlN/GaN heterostructures grown by MOCVD

The present work reports the effect of gamma-irradiation on the AlInGaN/AlN/GaN heterostructures with different doses: 75 kGy and 150 kGy. The compositional fluctuation and intermixing of the epilayers after gamma irradiation was realized by High Resolution X-ray diffraction. For 75 kGy and 150 kGy samples, the AlInGaN layer was merged with AlN interlayer after gamma irradiation which was realized by simulation fits ω-2θ scans along (0002) plane. The Raman studies showed the degradation in crystalline quality of the gamma-irradiated samples and also confirmed that the alloy compositional fluctuations are due to In(Ga)N-like clusters in the AlInGaN epilayer. The optical properties of the samples were carried out using the room temperature Photoluminescence, which confirms the suppression of In(Ga)N-like clusters after gamma-irradiation. Morphological studies by Atomic Force Microscopy showed decrease in density of the V-pits with increasing gamma-dose. The Hall measurements confirmed the degradation in mobility, carrier concentration and sheet resistance after gamma-irradiation. Though AlInGaN samples underwent heavy doses of gamma-irradiation, the samples showed an electrical response which indicates that they will be suitable for use in harsh environments.