Kasim Uthman Isah

Effect of different copper precursor layer thickness on properties of Cu2ZnSnS4 (CZTS) thin films prepared by sulfurization of thermally deposited stacked metallic layers

Cu2ZnSnS4 (CZTS) thin films were fabricated by sulfurization of thermally evaporated metallic precursors on glass substrates. While the Zinc and Tin thicknesses were kept constant at 300 and 200nm respectively, three Copper layer thicknesses of 100, 150 and 200 nm were used to obtain the metallic precursors. The precursor films were sulfurized for 3 hours at 550 0 C with an initial ramping rate of 10 0 C/min. X-ray diffraction studies reveal polycrystalline films exhibiting Kesterite structures with preferential orientation along (112) direction. The films with lowest Cu layer thickness exhibited binary metal alloy contents, which disappears with higher Cu precursor layer thickness. The surface morphology and elemental composition of CZTS thin films was determined from scanning electron microscopy and energy dispersive spectroscopy analysis respectively. The grain size become large with increasing Cu/(Zn + Sn) ratio, exhibiting an enhancement of the grain growth under Cu - rich condition. There is a nominal increase in the optical band gap from 1.49 to 1.51 eV with increase in Cu content. The samples resistivities are in the range of 0.8 to 1.5Ωcm Keyword - CZTS, Sulfurization, Thermal evaporation. XRD, SEM.

Review on Material Synthesis and Characterization of Sodium (Na) Super-Ionic Conductor (NASICON)

Sodium (Na) Super Ionic Conductor (NASICON) has general formula Na1+ x Zr2P3- xSi x O12 (0 ≤x ≤ 3) derived from its parent compound, sodium zirconium phosphate NaZr2(PO4)3 (NZP) which belong to a rhombohedral crystal structure. This material consists of three-dimensional structure with interesting features such as low thermal expansion coefficient, thermal stability, gas sensor and nuclear waste immobilization that make it viable for industrial applications. Current study presents comprehensive studies on the synthesis and essential characteristics required to understand the theory behind the mechanism that justifies the study of NASICON structure and its application such as lithium ion rechargeable battery, gas sensor, and nuclear waste immobilization and so on.

Growth mechanism and optical properties of zinc oxide thin film

Zinc oxide (ZnO) thin films were successfully deposited on glass substrate by radio frequency (RF) sputtering technique. One set of the samples was annealed in open air at temperatures of 423 K, 573 K and 723 K for one hour while another set of samples was annealed under nitrogen atmosphere for the same duration of time and temperature as the other set. A growth mechanism for thin film growth by RF sputtering has been presented. The films were also characterised to assess their optical properties. The ZnO thin films showed good transmittance, low reflectance and good absorbance in the visible region. The energy band gap (Eg) obtained is in the range of (3.15–3.28 eV) which is good for window layer of a solar cell. Other optical constants evaluated include refractive index and the extinction coefficient.