ABSTRACT:A novel and simple chemical route was used for the deposition of ZnO thin film from aqueous solution of zinc-ammonia complex, integrating the merits of successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition methods. ZnO thin films on glass substrates were deposited with the precursor of zincammonia complex. Characterization techniques of XRD, SEM, EDAX and DRS are used to characterize ZnO thin films. X-ray diffraction study show that the film prepared in this work exhibits good crystallinity with the hexagonal wurtzite crystalline structure and the preferential orientation along (0 0 2) plane, with a texture coefficient value of ~2.56, average crystallite size of 28.92 nm and with lattice constants a = b = 3.257 Å, c = 5.215 Å. EDAX spectrum indicates that the film consists of zinc and oxygen elements. The optical band gap energy of the thin films is calculated from optical absorption spectrometry using DRS data and the value was found to be direct allowed transition ~3.22 eV.
INTRODUCTIONNanostructured materials have drawn attentions to the researchers due to the unique physical and chemical properties of nanomaterials, which are different from those of either the bulk materials or single atoms [1]. The reduction of the size of materials causes a deviation of their physical and chemical properties from the bulk and such resultant materials (nanoparticles) are known to possess potential applications and novel properties [2]. Among the different metal oxide films, CdO is an important n-type semiconductor with a cubic structure, which belongs to the II-VI group, with a direct band gap of 2.5 eV and indirect band gap 1.98 eV [3] Nanostructured cadmium oxide thin films have been synthesized onto suitably cleaned glass substrates by SILAR (successive ionic layer adsorption and reaction) method. X-ray diffraction study confirms the formation of nanocrystalline cubic phase of cadmium oxide in the films. Lattice constant is determined using Nelson Riley plots. Using X-ray broadening, crystallite sizes, lattice strain, stress and energy density were studied by using Williamson-Hall method and modified Williamson-Hall method. From literature review, it is seen that a number of researchers have applied these two methods for structural characterization of thin films of different nanocrystals, but till now modified Williamson-Hall method has not been used for CdO nanocrystals. Hence, we have used these methods for structural characterization of deposited CdO thin films. The ultra-high resolution transmission electron microscopic (UHRTEM) study shows that the shape of the particles is nearly spherical and the average particle size agrees well with the result obtained from X-ray diffraction study. Selected area electron diffraction patterns have also supported the formation of cubic phase of cadmium oxide.
CdSe is a well-known semiconductor which finds applications as photoconductors, photovoltaic cells and other optoelectronic devices. In this paper structural studies and carrier concentration measurements of vacuum evaporated CdSe films obtained by using CdSe synthesized by simple precipitation technique are presented.
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