Effect of deposition pressure on structural, optical and electrical properties of zinc selenide thin films

• Published in: Physica. B, Condensed matter Condensed matter, 2011-04, Vol.406 (9), p.1757-1762
• Main Authors: Sharma, Jeewan, Tripathi, S.K.
• Format: Article
• Language: English
• Subjects: Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Deposition; Diffraction; Electrical; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Ii-vi semiconductors; Inert gas condensation; Mathematical analysis; Optical properties; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photoconduction and photovoltaic effects; photodielectric effects; Physics; Recombination and photoconductivity; Structural; Thin films; X-rays; Zinc selenides; ZnSe thin films
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2011.02.022

ZnSe thin films have been prepared by inert gas condensation method at different gas pressures. The influence of deposition pressure, on structural, optical and electrical properties of polycrystalline ZnSe films have been investigated using X-ray diffraction (XRD), optical transmission and conductivity measurements. The X-ray diffraction study reveals the sphalerite cubic structure of the ZnSe films oriented along the (111) direction. The structural parameters such as particle size [6.65–22.24nm], strain [4.01–46.6×10−3lin−2m−4] and dislocation density [4.762–18.57×1015linm−2] have been evaluated. Optical transmittance measurements indicate the existence of direct allowed optical transition with a corresponding energy gap in the range 2.60–3.00eV. The dark conductivity (σd) and photoconductivity (σph) measurements, in the temperature range 253–358K, indicate that the conduction in these materials is through an activated process having two activation energies. σd and σph values decrease with the decrease in the crystallite size. The values of carrier life time have been calculated and are found to decrease with the reduction in the particle size. The conduction mechanism in present samples has been explained, and the density of surface states [9.84–21.4×1013cm−2] and impurity concentration [4.66–31.80×1019cm−3] have also been calculated.