Fabrication and temperature-dependent band gap shrinkage of α-phase Bi₂O₃ thin films grown by atomic layer deposition method

¹ Key Laboratory for Polar Materials and Devices of Ministry of Education, East China Normal University, Shanghai 200241, P.R. China
² National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, P.R. China

^a e-mail: syd4182@163.com

Received: 16 September 2012
Accepted: 8 April 2013
Published online: 22 May 2013

Abstract

α-Bi₂O₃ thin films were deposited on different substrates by atomic layer deposition method. The results of X-ray diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscope correspond to α-Bi₂O₃. The Fourier transform infrared spectroscopy analyses indicate that the reaction is rather complete during the deposition. Optical properties of the films have been investigated using ultraviolet-infrared transmittance spectra in the temperature range of 8–300 K. It is found that the band gap E_g decreases from 3.12 to 3.03 eV with the temperature. The parameters α_B and Θ_B of the Bose-Einstein model are 69.3 meV and 293.9 K, respectively. The band narrowing coefficient dE_g/dT is −0.435 meV/K at room temperature. The present results can be considerable for future application of Bi₂O₃-based electro-optic and wide temperature range optoelectronic devices.