Gamma radiation-induced modifications in structural, optical, and electrical characteristics of p-NiO/n-Si heterojunction diodes

Abstract

This study examines the effects of Co-60 gamma irradiation on the structural, chemical, optical, and electrical properties of p-NiO/n-Si heterojunction diodes. Various characterization techniques such as X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, UV–Vis reflectance measurements, and electrical current-voltage (I–V) analysis were used to evaluate the changes caused by radiation. The XRD analysis showed that higher radiation doses caused shifts and broadening in the diffraction peak positions, which indicated a reduction in stress and an increase in grain size in the irradiated films. FTIR spectra revealed the weakening of Ni–O–Si bonds, as well as the emergence of Ni–O and Si–O stretching vibrations, particularly in film structures exposed to higher doses. Optical analyses demonstrated a decrease in bandgap energy values to 3.40 eV, 3.36 eV, and 3.34 eV due to the band tailing effect related to radiation-induced defects. Electrical measurements indicated a decrease in sheet resistance from 78.4 Ω/sq to 64.4 Ω/sq, changes in the diode's rectification behavior, and an increase in barrier height from 0.79 eV to 0.87 eV with higher radiation doses, while the ideality factor increased from 1.64 to 1.83. These findings highlight the significant effects of gamma irradiation on the structural and electronic properties of heterojunction diode materials and provide valuable insights for the design of radiation-resistant semiconductor devices.