Influence of annealing temperature on the structural and optical properties of highly-oriented Al and Er co-doped ZnO films

• Published in: Journal of materials science. Materials in electronics 2013-10, Vol.24 (10), p.3868-3874
• Main Authors: Kong, Ji-Zhou, Wang, Zheng, Luan, Chun-Yan, Wang, Mei-Ling, Zhou, Fei, Wu, Xue-Mei, Zhang, Wen-Jun, Zhu, Kong-Jun, Qiu, Jin-Hao, Zapien, Juan-Antonio, Lee, Shuit-Tong
• Format: Article
• Language: English
• Subjects: Aluminum; Annealing; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronics; Erbium; Exact sciences and technology; Grain size; Heat treatment; Materials; Materials Science; Metals. Metallurgy; Optical and Electronic Materials; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Orientation; Physics; Production techniques; Transmittance; Treatment of materials and its effects on microstructure and properties; Zinc oxide
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-013-1331-y

High-quality c -axis oriented 7 mol% Al and 1.5 mol% Er co-doped ZnO films (ZEAO) were prepared on the quartz glass substrates by using sol–gel method. The influence of the annealing temperature on the crystal orientation, microstructure and optical properties of the ZEAO thin films were studied by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and UV–vis transmittance spectrophotometer, respectively. XRD results revealed that all the samples were polycrystalline with hexagonal structure and exhibited (002) preferential orientation. With increasing the annealing temperature, the grain size and orientation extent increased. The optical studies showed each ZEAO film had a relatively high transmittance above 85 %. The transmittance as high as 95 % was obtained at the annealing temperature of 800 °C, and the corresponding average grain size was about 50 nm. The cathodoluminescence (CL) spectra of these films were also used to characterize the luminescence properties. Strong UV emission centered at 380 nm was observed in the CL spectra taken for the pure ZnO. For the ZEAO sample, the blue-green emission is related to the 4 f shell transition in the Er 3+ ions of ZnO matrices, corresponding to a transition from the excited states ( 4 F 5/2 ).