The Study On Infrared Optical Properties Of ZnO: Al³⁺ (Ni²⁺)

ZAO (Al-doped ZnO) thin films have a lot of important applications because of its wide band gap and conductivity. Researchers have paid attention in its infrared optical properties. In this article, The ZAO thin films were deposited on quartz glass substrates by dip coating method and the transparent sol was synthesized by sol-gel method. The phase structures,the surface morphologies,transparent properties and infrared emissivity were investigated. Some conclusions were drawed from our experients:1,The XRD results showed that no peaks of Al₂O₃ occured in the XRD patterns and diffraction peaks and variation of d- spacing of ZnO in the films were found as the concentration went up at the same time. They implied that Al was doped into ZnO lattice sueeessfully. The Phase structure of ZAO thin films were the same as ZnO with highly C-axis oriented . The particals was inhibited when the concentration reached to 15mol%.2,The annealing temperature had great effects on the highly C-axis oriented properties. The ZAO particals were small and inhomogeneous in the low temperature of 500 degree while had a good crystallization at 700 degree . In the temperature of 700 degree, the ZAO films had a goog C-axis oriented property and a higher transmission value about 80% in the visible region(400-780nm). The ZAO films annealed at 700 degree had a high infrared transmission and took a low infrared emissivity which was 0.713 in the 8-14um region .3,As the doping concentration went up from 0mol% to 9mol%,the XRD results showed that the c-axis oriented property varied with Al doping concentration. With doping concentration of 6mol%, the crystallization of ZAO films was the best in which the emissivity was lowed to 0.731 and the infrared transmission value was 78%.The transmission value in visible region went down as the concentration went up.4,ZAO grains in thinner films whose thickness was about 80nm showed random growth while certain orientation growth of ZAO grains was found in 1μm-thick films during the same heat treatment. The infrared emissivity was 0.811 with thinner films which may be affected by the quartz glass ,while the emissivity was about 0.735 with thicker films.At last, according to the good absorbing abilities of magnetic nanoparticals, Ni-doped ZnO thin films were fabricated through the same method as ZAO. The XRD result showed that Ni-doped ZnO had a c-axis oriented property and the annealing temperature had great effects on crystallization. Ni-doped ZnO had a highest transmission in the visible and inrared region at the heat treatment temperature of 600 degree,but its emissivity value was higher than 0.8.There are 26 figures, 3 tables and 32 references in this paper.