Observation of negative photoconductivity in (ZnO) x (CdO) 1− x films

• Published in: The Journal of physics and chemistry of solids Vol. 70; no. 3; pp. 521 - 526
• Main Authors: Kavasoglu, Nese, Kavasoglu, A. Sertap, Oktik, Sener
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-03-2009; Elsevier
• Subjects: A. Optical materials; A. Thin films; Condensed matter: electronic structure, electrical, magnetic, and optical properties; D. Electrical conductivity; D. Electrical properties; D. Optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Photoconduction and photovoltaic effects; photodielectric effects; Physics; A. Thin films; A. Optical materials; D. Optical properties; D. Electrical conductivity; D. Electrical properties; Cubic lattices; Transient photoconductivity; Interband transitions; Spray coatings; Negative photoconductivity; Photoluminescence; Ultrasonic waves; XRD; Dark conductivity; Thin films; Hexagonal lattices; Energy gap; Ultraviolet radiation; Temperature effects; Wurtzite structure; Zinc oxide; Cadmium oxide
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2008.11.018

In this study, (ZnO)
x
(CdO)
1−
x
films were prepared by ultrasonic spray pyrolysis (USP) technique at a substrate temperature of 400
°C. X-ray diffraction patterns of the films indicate that the (ZnO)
x
(CdO)
1−
x
films have hexagonal wurtzite and cubic structure for the constituent materials. A decrease in the average transmission with increasing quantity of the cadmium acetate dehydrate in the sprayed solution was observed. The photoconductivity transients were performed using UV light, which has 360
nm wavelength. After light cut off, conductivity changed slowly, and the decay time was thousands of seconds. The films with
x=0.2 and 0 exhibited negative photoconductivity. Temperature-dependent photoconductivity and dark conductivity measurements were performed and negative photoconductivity was also observed for the same films (
x=0.2 and 0). Photoluminescence measurements were performed and band-to-band excitation energies of (ZnO)
x
(CdO)
1−
x
films were determined. Band gap of the pure CdO film was found as 3.11
eV, interestingly.