Investigation of the Effects of Rapid Thermal Annealing on the Electron Transport Mechanism in Nitrogen-Doped ZnO Thin Films Grown by RF Magnetron Sputtering

Nitrogen-doped ZnO (ZnO:N) thin films, deposited on Si(100) substrates by RF magnetron sputtering in a gas mixture of argon, oxygen, and nitrogen at different ratios followed by Rapid Thermal Annealing (RTA) at 400 degrees C and 550 degrees C, were studied in the present work. Raman and photoluminescence spectroscopic analyses showed that introduction of N into the ZnO matrix generated defects related to oxygen and zinc vacancies and interstitials. These defects were deep levels which contributed to the electron transport properties of the ZnO:N films, studied by analyzing the current-voltage characteristics of metal-insulator-semiconductor structures with ZnO:N films, measured at 298 and 77 K. At the appliedtechnological conditions of deposition and subsequent RTA at 400 degrees C n-type ZnO:N films were formed, while RTA at 550 degrees C transformed the n-ZnO:N films to p-ZnO:N ones. The charge transport in both types of ZnO:N films was carried out via deep levels in the ZnO energy gap. The density of the deep levels was in the order of 10(19) cm(-3). In the temperature range of 77-298 K, the electron transport mechanism in the ZnO:N films was predominantly intertrap tunneling, but thermally activated hopping also took place.

Automated summary

In this study, nitrogen-doped zinc oxide (ZnO:N) thin films were deposited on Si(100) substrates and analyzed for their spectroscopic and electron transport characteristics. The introduction of nitrogen resulted in defects related to oxygen and zinc vacancies, and the films exhibited different conductivity properties depending on the annealing temperature. Furthermore, the electron transport mechanism was found to be mainly governed by deep levels in the ZnO energy gap.