Manuel J. Mendes Website
Professor of Photonics, Photovoltaics and Optoelectronics subjects
CENIMAT-i3N and CEMOP-UNINOVA, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa. Campus de Caparica. 2829-516 Caparica. Portugal (email)
CENIMAT-i3N and CEMOP-UNINOVA, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa. Campus de Caparica. 2829-516 Caparica. Portugal (email)
In this work, we highlight the influence of three different sol stabilizers, namely diethanolamine (DEA), Ammonium Hydroxide (NH4OH), and Nitric Acid (HNO3), on the optical and structural properties of spin-coated zinc oxide (ZnO) thin films. The XRD patterns related to all films exhibit a hexagonal crystal structure with a preferential orientation along the (0 0 2) direction. However an additional {\textless}100{\textgreater} peak arises when the films are prepared with DEA and NH4OH showing a better crystallinity than that displayed by HNO3-prepared films. The elaborated films show a high transparency reaching 80{%} for DEA-prepared films. The analysis of the transmittance and the reflectance measurements confirms a direct band-to-band transition. Depending on the sol stabilizer, the optical band gap energy is varying from 3.16 to 3.22 eV. The relatively wide band-gap of DEA-prepared ZnO films is correlated to their high crystallinity. Room temperature photoluminescence spectra indicate strong UV emission at around 377 nm originated from nearby band-edge transitions. Yet, the use of DEA as a stabilizer leads to a net intensity increase of the blue peak emission.
n/a