Influence of growth temperature on electrical, optical, and plasmonic properties of aluminum:zinc oxide films grown by radio frequency magnetron sputtering

Abstract

We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (T s ). The films were found to be crystalline with the electrical resistivity close to 1.1 Â 10 À3 X cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at T s of 400 C, however, a slight decrease in the bandgap was noticed above 400 C, which can be explained by Burstein-Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at $110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels. V C 2013 AIP Publishing LLC. [http://dx

The influence of Ce doping on the structural and optoelectronic properties of RF-sputtered ZnO films

“…Optical absorption studies show that the absorption edge of the doped films shifts towards blue region with a widening of the band gap at a higher energy. Such a feature is related to the rising Fermi level by filling more electrons in the conduction band (Burstein-Moss effect) (Dondapati et al 2013;Kim et al 2010b;Luo et al 2012). When Ce atoms are incorporated into ZnO, both ions ðCe 3þ ; Ce 4þ Þ, whether in substitutional or interstitial sites, tend to increase the carrier concentration.…”

“…ZnO has a würzite crystalline structure (lattice spacing a 0 ¼ 3:24Å and c 0 ¼ 5:20Å). ZnO also possesses a wide ordinary optical band gap ðE g Þ of 3.3 eV, which makes it transparent in the UVVis-NIR region, and a large exciton binding energy (60 meV), which enhances the luminescence efficiency of light emission (Dondapati et al 2013;Gayen et al 2011;AlKuhaili et al 2012). This material has garnered much commercial and scientific interest compared with other TCO films, such as indium tin oxide (Minami 2005).…”

“…Zinc oxide (ZnO) is a binary transparent conducting oxide (TCO) with properties of great interest due to their basic scientific research and potential technological applications (Dondapati et al 2013;Ammaih et al 2014;Sachet et al 2013;Suchea et al 2006;Logothetidis et al 2008;Frölich and Wegener 2011). ZnO has a würzite crystalline structure (lattice spacing a 0 ¼ 3:24Å and c 0 ¼ 5:20Å).…”

Investigation of the annealing effects on the structural and optoelectronic properties of RF-sputtered ZnO films studied by the Drude–Lorentz model

“…ZnO has a würzite crystalline structure (lattice spacing a 0 ¼ 3:24 A and c 0 ¼ 5:20 A ). ZnO also possesses a wide ordinary optical band gap ðE g Þ of *3.3 eV, which makes it transparent in the UV-Vis-NIR region, and a large exciton binding energy (60 meV), which enhances the luminescence efficiency of light emission [1,7,8]. This material has garnered much commercial and scientific interest compared with other TCO films, such as indium tin oxide [9].…”

“…Zinc oxide (ZnO) is a binary transparent conducting oxide (TCO) with properties of great interest due to their basic scientific research and potential technological applications [1][2][3][4][5][6]. ZnO has a würzite crystalline structure (lattice spacing a 0 ¼ 3:24 A and c 0 ¼ 5:20 A ).…”