Properties of ZnO thin films deposited by chemical bath deposition and post annealed

• Published in: Journal of physics. D, Applied physics Applied physics, 2006-05, Vol.39 (9), p.1954-1959
• Main Authors: Ouerfelli, J, Regragui, M, Morsli, M, Djeteli, G, Jondo, K, Amory, C, Tchangbedji, G, Napo, K, Bernède, J C
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/39/9/035

ZnO thin films deposited by chemical bath deposition (CBD) have been studied using x-ray diffraction, scanning electron microscopy, electron microprobe analysis and electrical measurements. The optimum CBD conditions for achieving structured, but adherent, ZnO films are as follows. Zinc acetate (0.0188 mol l-1) and ethylenediamine (0.03 mol l-1) are mixed. The pH of the bath is raised by addition of a base (0.5 mol l-1, NaOH). The solution is maintained at a temperature between 60 deg C and 65 deg C, while the bath is continuously stirred. We proceeded to anneal in room air for 30 min at 300 deg C and under vacuum for 2 h at 300 deg C. All the films obtained are nearly stoichiometric ZnO films crystallized in the usual hexagonal structure. As expected the films are rough and porous. The main difference between the two ZnO film families is their conductivity. The conductivity of the films annealed under vacuum is five orders of magnitude higher than that of those annealed in room air.