Characterization of vacuum-evaporated ZnSe thin films

ZnSe thin films were prepared at different thicknesses using a vacuum evaporation technique under a vacuum of 3.9 x 10(-8) bar. The composition, structure, optical and electrical properties of the deposited ZnSe thin films were studied using the energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), optical transmittance and current-voltage measurements. The composition of the deposited films was found to be Zn (34.35%) and Se (65.65%). SEM images of ZnSe films on glass substrates revealed the smooth surface of the deposited films. X-ray analysis showed that the films deposited at a lower thickness were amorphous in nature, whereas at higher thicknesses, the films were crystalline in nature. The XRD patterns for higher thickness films exhibited reflections corresponding to the cubic (111) phase (20=27.33). The values of the estimated energy gap from optical studies for amorphous films were greater than that obtained for crystalline ZnSe (E-g=2.7 eV) films. In the do conduction studies, the free carrier mobility (pp), carrier density (po) and trap density values were calculated as 9.1738 X 10(15) m(2) V(-1)s(-1), 1.068 X 10(23) m(3) and 4.2733 X 10(22) m(-3), respectively. (C) 2006 Elsevier Inc. All rights reserved.