Elemental, structural and optical properties of nanocrystalline Zn 1−x Cu x Se films deposited by close spaced sublimation technique

Abstract

Abstract The elemental composition, film thickness and concentration depth profiles of as-deposited and annealed Zn 1−x Cu x Se films were studied by the Rutherford backscattering spectrometer (RBS) technique. The films were deposited on glass substrates by close spaced sublimation (CSS) technique. As-deposited films of about 250–300 nm thickness were then annealed in air at temperatures of 200 °C and 400 °C for 1 h. Structural characterization including crystal structure, crystal orientation, stacking fault energy ( Ү SFE ) and surface morphology were carried out by using X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD studies revealed that the fabricated films are polycrystalline with a zinc-blende structure and a strong (111) texture plane. Surface roughness was observed to be enhanced with annealing temperature with a decrease in stacking fault energy ( Ү SFE ). Spectroscopic ellipsometry has been utilized for the estimation of band gap energy (E g ) and dielectric constant (e 1 ). Band gap energy of the film increased with increasing annealing temperature while the dielectric constant decreased.