Nanomaterials and Nanotechnology

Biography

Biography: M A Jafarov

Abstract

The II–VI semiconductor nano-crystals exhibit interesting properties and their emission spectra is narrow (spectrally pure) and the emission color is simply tuned by changing their size. As the nano-crystal size decreases, the energy of the first excited state decreases qualitatively following a particle-in-a-box behavior. This size dependence and the emergence of a discrete electronic structure from a continuum of levels in the valence and conduction bands of the bulk semiconductor result from quantum confinement; hence, semiconductor nano-crystals are referred to as quantum dots). Nanostructure ZnCdS thin film was fabricated onto cleaned glass substrates with thickness 100 nm by flash deposition technique. Cleaning of substrate is important in fabrication of thin films, because it greatly influences the properties of the films deposited on it and has strong effect on the adhesion properties of the deposited films. The electrolyte was prepared by dissolving 6mM CdCl2, 5mM CdSO4, 0.15mM Na2S2O3 and 0.2M NaOH in water. Due to the low solubility of Na2S2O3 continuous heating and stirring for several hours is required. The pH of the final electrolyte was adjusted to 3.5 with H2SO4.. After preparing the nPS samples by using the Electrochemical etching process, the Nanostructure ZnCdS thin films with thickness 100 nm were deposited on the porous silicon layers; this is achieved by using Flash evaporation technique for preparation Nano-ZnCdS/PS hetero-junction. The crystallographic structure of films was analyzed with x-ray diffractometer using Cu-Kα (λ=1.54Å) radiation. Diffraction patterns have been recorded over the 2θ range of 20o to 60o. The surface morphology and roughness of prepared samples were obtained by atomic force microscopy (Scanning probe Microscope type AA3000), supplied by Angstrom Advanced Inc. in non-contact mode. The transmission spectrums of Nanostructure ZnCdS thin film was obtained using UV-Visible recorder spectrophotometer in the wavelength range (200-1100) nm. The electrical measurement for Nano-ZnCdS/PS hetero-junction, which was prepared at constant substrate temperature with different etching times of nPS layers, includes current-voltage characteristic measurements in the dark and under illumination conditions.