Effect of annealing on conductivity behavior of undoped zinc oxide prepared by rf magnetron sputtering

• Published in: Journal of alloys and compounds Vol. 457; no. 1; pp. 36 - 41
• Main Authors: Xing, G.Z., Yao, B., Cong, C.X., Yang, T., Xie, Y.P., Li, B.H., Shen, D.Z.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 12.06.2008; Elsevier
• Subjects: Annealing; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electrical properties of specific thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Ii-vi semiconductors; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photoluminescence; Physics; ZnO films; 71.55.Gs; Annealing; 71.35.−y; 78.66.−w; Photoluminescence; 78.55.−m; ZnO films; 78.55.-m; Vacancies; 78.66.-w; Interstitials; Lattice parameters; Thin films; Cathode sputtering; Acceptor center; Temperature effects; Electrical conductivity transitions; Zinc oxide; Donor center; 71.35.-y; Radiofrequency sputtering; X-ray photoelectron spectra
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2007.03.071

An undoped ZnO thin film with high resistivity was prepared by rf magnetron sputtering on the quartz substrates using a ZnO (99.999% pure) as target and high pure Ar as sputtering gas. Upon annealing in a temperature range from 513 to 923 K under 10 −3 Pa, the conductive properties of the film change from high resistivity, to n-type, then to p-type and finally to n-type with increasing annealing temperature and the p-type ZnO film was fabricated near 863 K reproducibly. Temperature-dependent photoluminescence (PL) of the p-type ZnO shows a dominant PL band at 3.072 eV at low temperature, which is related to Zn vacancy (V Zn) acceptor. The intensity of the 3.072 eV band decreases with increasing temperature, implying increment of amount of the hole induced by V Zn. X-ray photoelectron spectroscopy (XPS) and room temperature PL measurements indicate that the undoped ZnO is Zn-rich and has oxygen vacancy (V o) and interstitial Zn (Zn i) donor defects. The amount of V o and Zn i donors changes with the annealing temperature. The intrinsic p-type conduction of the undoped ZnO film is ascribed to that the V Zn acceptor concentration can compensate V o and Zn i donor concentration.