Structural and photoluminescence properties of ZnO thin films prepared by sol-gel process

• Published in: Journal of applied physics 2008-12, Vol.104 (11), p.113539-113539-5
• Main Authors: Petersen, J., Brimont, C., Gallart, M., Crégut, O., Schmerber, G., Gilliot, P., Hönerlage, B., Ulhaq-Bouillet, C., Rehspringer, J. L., Leuvrey, C., Colis, S., Aubriet, H., Becker, C., Ruch, D., Slaoui, A., Dinia, A.
• Format: Article
• Language: English
• Subjects: Condensed Matter; Other; Physics
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3021358

The present study focuses on the structural and optical properties of ZnO thin films fabricated by sol-gel process and spin coated onto Si (100) and quartz substrates. The ZnO films have a hexagonal wurtzite structure with a grain size of about 50 nm. The x-ray photoelectron spectroscopy measurements reveal the presence of Zn 2 + and of zinc hydroxyl groups at the film. Optical properties were studied by photoluminescence (PL) and absorption spectroscopy at low and room temperatures. The absorption spectrum is dominated by a sharp excitonic peak at room and low temperatures. At room temperature, PL observations show two transitions: one near the absorption edge in the ultraviolet (UV) region and the second centered at 640 nm, characteristic of the deep electronic levels in the bandgap. The spectrum at 6 K is dominated by donor bound exciton lines and donor-acceptor pair transitions. LO-phonon replica and two-electron satellite transitions are also observed. These optical characteristics are a signature of good structural quality of the films.