Influence of Ar Flow Rate on Al-doped ZnO Thin Films Deposited by RF Magnetron Sputtering

Al-doped ZnO(AZO)has been considered to be one of the most potential transparent conductive oxides(TCO)due to its low cost,abundant and nontoxic feature.The AZO films with the area of 30 cm×30 cm were prepared by RF magnetron sputtering in this paper,and the influences of different Ar flow rate at the same working pressure on the mechanism of grain growth,electrical properties as well as optical properties of AZO thin films were studied in detail.All the AZO films showed c-axis orientation along the(002)plane preferred grain growth which was weakened by raising Ar flow rate.The films showed the inhomogeneous grain size distribution on the surface and the number of large size grain was increased by raising Ar flow rate.Some rod-like grains appeared on the surface with a length of 100 nm and width of 30 nm.The carrier concentration ofAZO films increased slightly from 4.52×10²⁰cm^-3 to 6.2×10²⁰cm^-3 while the hall mobility was improved substantially from 4.79 cm²/(V·s) to 10.46 cm²/(V·s).The minimum resistivity of 1.01×10^-3Ω·cm was achieved when Ar flow rate was 94 mL/min.The average transmittance of more than 78%in the visible range is obtained for the samples and the band gap is estimated as 3.8 eV.