Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6615983 | Electrochimica Acta | 2013 | 8 Pages |
Abstract
ZnO:Al films were deposited at 70 °C at a fixed â1.1 V potential onto ITO substrates from a 0.01 M Zn(NO3)2 + x Al(NO3)3·9H2O electrochemical bath, with Al3+ concentrations between 0 and 2 mM. Electrodeposition conditions were optimized to remove bubbles, increase grain size homogeneity and ensure adherence. Films were characterized by field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis transmittance, electrochemical impedance spectroscopy and photocurrent spectroscopy. Films were crystalline with the wurtzite structure and present a morphology made of hexagonal nano-pillars. It was found that Al incorporation increases gradually up to â¼11 at% for samples prepared within the concentration range 0.0-0.3 mM Al3+ in the bath. For higher Al3+ contents (>0.4 mM) an amorphous Al2O3-like compound develops on top of the films. In the grown films with Al contents up to 11 at%, changes in the optical band gap from 2.88 eV to 3.45 eV and in the carrier densities from 1019 to 1020 cmâ3 were observed. The blue shift in the band gap energy was attributed to the Burstein-Moss effect. Changes in the photocurrent response and the electronic disorder were also discussed in the light of Al doping. Optical transmittances up to 60% at 550 nm were obtained, thus making these films suitable as transparent and conductive oxide films.
Keywords
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Physical Sciences and Engineering
Chemical Engineering
Chemical Engineering (General)
Authors
Albert C. Aragonès, A. Palacios-Padrós, F. Caballero-Briones, Fausto Sanz,