Dependence of structural, electrical, and optical properties of ZnO:Al films on substrate temperature

Abstract

ZnO:Al (ZAO) films were deposited on fused silica substrates heated to 350 °C by dc magnetron reactive sputtering from a Zn target mixed with 1.5 wt% Al. Films deposited on a substrate heated to a temperature between room temperature and 300 °C were (001)-oriented crystals, but those grown at 350 °C consisted of crystallites with (001) and (101) orientations. The dependence of electrical properties such as resistivity, carrier concentration, and Hall mobility on temperature was measured. The results indicate that the carrier concentration and Hall mobility increase with increasing temperature up to 250 °C, though the Al content remains unchanged in this temperature range. The probable mechanisms are discussed. The minimum resistivity of ZAO films is 4.23 × 10−4 Ω cm, with a carrier concentration of 9.21 × 1020 cm−3 and a Hall mobility of 16.0 cm2 v−1 s−1. The films show a visible transmittance of above 80%.

Microstructure evolution of Al-doped zinc oxide and Sn-doped indium oxide deposited by radio-frequency magnetron sputtering: A comparison

“…The crystallite sizes obtained here are of the same order of magnitude as reported by other authors. [13][14][15] The c-axis lattice constant shows the same tendency as the crystallite size which depends on the growth condition but is independent of film thickness. The lattice constant is 0.5249 6 0.0005 nm and 0.5267 6 0.0005 nm for 6.5 nm and 420 nm-thick films, respectively, which corresponds to a relative change of 0.4%.…”

Effect of indium doping on zinc oxide films prepared by chemical spray pyrolysis technique

“…Group III elements like Al, Ga and In can be used as n-type dopant (Kato et al 2002). Doping with Al, Ga and In has been attempted by many groups, resulting in high quality, highly conducting n-type ZnO thin films (Minami et al 1984;Ataev et al 1995;Myong et al 1997;Ko et al 2000;Chen et al 2001;Assuncao et al 2003;Liu et al 2003). Among group III element much of the work has been done by using Al as a dopant because the ionic radius of Al is smaller than that of In and Ga.…”

The effects of post-growth thermal annealing on the structural and electrical properties of RF-magnetron sputtered ZnO

“…where c 0 is the unstrained unit cell distance, and c is the measured unit cell distance. The constant of proportionality S is the corresponding elastic compliance, which for zinc oxide's hexagonal structure is given by Hong et al [15] and Chenet al [16]. Substituting into equation 1:…”