Characteristics of transparent conducting Al-doped ZnO films prepared by dc magnetron sputtering

Al-doped ZnO (AZO) films were deposited on soda-lime glass substrates by using dc magnetron sputtering as a function of argon gas pressure, O-2/Ar gas ratio and substrate temperature, and their electrical and optical properties were investigated. As a result, the resistivity of the AZO films decreased with decreasing argon gas pressure or O-2/Ar gas ratio. However, the lowest resistivity could be obtained at the substrate temperatures of 250 degrees C. The higher substrate temperature increased the resistivity a little. The transmittance was found to be very sensitive to O-2/Ar gas ratio and substrate temperature. Addition of a very small amount of oxygen to argon (1.23% of O-2/Ar ratio) or slight increase of the substrate temperature from room temperature to 150 degrees C enhanced the transmittance in visible region remarkably. Conclusively, the AZO films with low resistivity of order of 10(-4) Omega cm and high transparency in visible region could be prepared at the substrate temperatures of above 150 degrees C (the lowest resistivity of 3.19 x 10(-4) Omega cm at 250 degrees C) by dc magnetron sputtering and these films are applicable to various fields which require transparent conducting oxide films. (c) 2010 Elsevier B.V. All rights reserved.