Role of evaporation time on the structural and optical properties of ZnO films deposited by thermal evaporator

¹ Department of Physics, Government College University Faisalabad, 38000 Faisalabad, Pakistan
² Department of Physics, Government Post Graduate College Jhang, 35200 Jhang, Pakistan
³ Department of Physics, QAU, Islamabad, Pakistan

^a e-mail: ejaz_phd@yahoo.com

Received: 19 March 2015
Revised: 18 August 2015
Accepted: 15 October 2015
Published online: 18 December 2015

Abstract

Zinc oxide films are deposited on Si substrates by thermal evaporator for different evaporation times (ET). XRD pattern shows the development of different diffraction peaks related to Zn, ZnO and Zn₂SiO₄ phases which confirms the deposition of composite film. The orientation transformation is observed with increasing ET. The maximum peak intensity of ZnO (1 0 1) plane is observed at 3 h ET. The dislocation density observed in ZnO (1 0 1) plane varies from 1.53 × 10^-3 nm^-2 to 8.94 × 10^-3 nm^-2. The lattice parameters of ZnO are found to be a = 3.243 Å and c = 5.197 Å. FTIR analysis confirms the formation of ZnO films. SEM microstructures exhibit the formation nano-wires, nano-bars, nano-strips and nano-needles. The optical energy band gap of ZnO films deposited for various ET varies from 3.98 eV to 4.06 eV. Results show that the peak intensity of ZnO (1 0 1) plane, orientation transformation and the presence of Si content are responsible to increase the energy band gap of ZnO films.