Investigation of the effect of annealing temperature on optical properties of lanthanum-oxide thin films prepared by sol-gel method

• Published in: Surface & coatings technology 2019-05, Vol.365, p.164-172
• Main Authors: Gao, Gang, Yang, Lei, Dai, Bing, Xia, Fei, Yang, Zhenhuai, Guo, Shuai, Wang, Peng, Geng, Fangjuan, Han, Jiecai, Zhu, Jiaqi
• Format: Article
• Language: English
• Subjects: Annealing; Annealing temperature; Atomic force microscopy; Fourier transforms; Infrared spectroscopy; La2O3 films; Lanthanum; Lanthanum chlorides; Lanthanum oxides; Microscopy; Optical properties; Photoelectric emission; Raman spectroscopy; Sapphire; Sol-gel processes; Spectroellipsometry; Spectrum analysis; Substrates; Thin films; X-ray diffraction
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2018.07.001

As lanthanum oxide (La2O3) has a large bandgap, it exhibits excellent optical properties. In this work, La2O3 thin films are prepared by the sol-gel method from a lanthanum chloride (LaCl3) precursor, on quartz and sapphire (0001) substrates. The effect of the annealing temperature (400–800 °C) on the optical properties of the La2O3 films is investigated. The structure and optical properties are analyzed by X-ray diffraction, atomic force microscopy, scanning electronic microscopy, X-ray photoemission spectroscopy, Raman spectroscopy, ultraviolet (UV)–visible spectroscopy, Fourier transform infrared spectroscopy, and infrared variable angle spectroscopic ellipsometry. Results indicate that with an annealing temperature of ~600 °C, the roughness and optical properties of La2O3 films can be significantly improved. •La2O3 thin films are prepared by sol-gel method on quartz and sapphire substrates.•Effect of annealing temperature on their optical properties is investigated.•Results indicate that the best annealing temperature is around 600 °C.•The roughness and optical properties of films are significantly improved.