Effect of γ-Irradiation on Structure and Electrophysical Properties of S-Doped ZnO Films

Abstract

The produced ZnO<S> films were characterized with the crystallographic orientation (001) and lattice parameters a = b = 0.3265 nm and c = 0.5212 nm. ZnO1—хSх nano-crystallites on the surface of the film had characteristic sizes ranging from 50 nm to 200 nm. The lattice parameter of ZnO1—хSх nano-crystallites was experimentally determined to be aZnO<S>= 0.7598 nm. The study has shed light on what occurs to lattice parameters of the ZnO film and the geometric dimensions of ZnO1—хSх nano-crystallites on the surface of the film under the influence of gamma-irradiation. It has been determined that the crystal structure of ZnO1—хSх nanocrystallites represents a cubic lattice and belongs to the space group F43m. It has been determined that after γ-irradiation at doses 5∙106 rad, the resistivity of ZnO<S> films reduced to ρ = 12,7 W∙cm and the mobility of the majority charge carriers (µ) became 0.18 cm2/V∙s, whereas their concentration (N) had increased and equaled 2.64∙1018 cm-3. The study of the current-voltage characteristics of p- ZnO<S>/n-Si heterostructures before and after γ‑irradiation at doses of 5∙106 rad revealed that the dependence of the current on voltage obeys an exponential law which is consistent with the theory of the injection depletion phenomenon. It was determined that under the influence of γ-irradiation at doses of 5∙106 rad, the capacitance of the p-ZnO<S>/n-Si heterostructure at negative voltages increases and the shelved curve sections and peaks are observed on the curve due to the presence of a monoenergetic level of fast surface states at the heterojunction.