Effects of oxygen concentration on the properties of Al-doped ZnO transparent conductive films deposited by pulsed DC magnetron sputtering

• Published in: Materials science in semiconductor processing 2013-06, Vol.16 (3), p.997-1001
• Main Authors: Kim, Doo-Soo, Park, Ji-Hyeon, Lee, Su-Jeong, Ahn, Kyung-Jun, Lee, Mi-So, Ham, Moon-Ho, Lee, Woong, Myoung, Jae-Min
• Format: Article
• Language: English
• Subjects: Al-doped ZnO (AZO); Aluminum; Azo; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition; Deposition by sputtering; Deterioration; Direct current; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Magnetron sputtering; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Oxygen/argon ratio; Physics; Pulsed DC magnetron sputtering; Semiconductors; Transparent conductive oxide; Zinc oxide
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2013.02.012

The effect of oxygen concentration on the properties of Al-doped ZnO (AZO) transparent conductive films has been investigated on the films deposited by pulsed DC magnetron sputtering using a cylindrical ZnO target containing 2wt% Al. AZO films were deposited at 230°C to the thickness of about 1000nm and the oxygen concentration was controlled by varying the O2/Ar supply ratio from 0 to 0.167. With the increasing O2/Ar ratio, crystallinity of the AZO films deteriorated while the film surface became smooth. Accompanying this, electrical properties also deteriorated significantly. When the O2/Ar ratios were 0 and 0.033, the AZO films showed metallic conduction behavior with the electrical resistivity in the mid 10−4Ωcm range. However, when the ratios were 0.100 and 0.167, the films showed poor electrical conduction behavior similar to semiconductors as deduced from the transmittance behavior. Spectroscopic analysis showed that such deteriorating properties are due to the formation of condensed oxide group through the reaction between excess oxygen and dopant aluminum.