Enhancement of Exciton Emission from Zno Nanocrystalline Films by Pulsed Laser Annealing

TL;DR

This study demonstrates that pulsed laser annealing enhances exciton emission in ZnO nanocrystalline films by reducing non-radiative centers and defect-related emissions, especially when combined with hydrogen passivation.

Contribution

It introduces a combined laser annealing and hydrogen passivation method to improve optical quality of ZnO nanostructured films.

Findings

Increased exciton photoluminescence efficiency.

Reduced defect-related orange and green emissions.

Hydrogen passivation yields defect-free nanostructured films.

Abstract

Pulsed ArF laser annealing in air and in hydrogen atmosphere improves the optical properties of ZnO nanostructured films. Independently on the ambient atmosphere, laser annealing produces two major effects on the photoluminescence (PL) spectra: first, the efficiency of the exciton PL increases due to decrease of the number of non-radiative recombination centers; second, the intensity of the defect-related orange band decreases because of the removing of excessive oxygen trapped into the films during deposition. However, annealing in the ambient air also increases the intensity of the green band related to oxygen vacancies. We show that the combination of laser annealing and passivation of oxygen vacancies by hydrogen results in films free of defect-related emission and keeps intact their nanostructural character.