Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Electrical Properties

Characteristics Study of ZnO Thin Films by Rapid Thermal Oxidation Treatment Technique

Uday Muhsin Nayef; Mohammed Jamal Jasim

Engineering and Technology Journal, 2015, Volume 33, Issue 1, Pages 37-44

In this paper preparation of good quality transparent conductive ZnO thin films by post-oxidation of vacuum evaporated Zn, on glass and silicon (p-type) as substrates, the oxidation was achieved in a short time (90 sec) which is known as rapid thermal oxidation. One growth parameter has been considered to specify the optimum conditions the film thickness are (200,300,400 &500 nm).
The XRD spectra revealed a high oriented grain in the (002) lattice system which is hexagonal wurtzite and proved that the ZnO films have a polycrystalline structure. Also, the morphological properties of ZnO films show that all films have a homogeneous surface morphology and it appears, to change significantly as a function of thickness.The energy gap of ZnO films decreases as the thickness increases. The FTIR spectra indicate the existence of the distinct characteristic absorption peak at 472.56cm-1 for Zn-O stretching mode.
Study of effect I-V and C-V measurements of ZnO films with the increase thickness. The photovoltaic properties confirmed that the photovoltaic depends strongly on the bias voltage and the amount of current produced by a photovoltaic device which is directly related to the number of photons absorbed. C-V results demonstrated that the fabricated heterojunction is of abrupt type. Also, the width of the depletion layer (w) follows the same behavior (V_bi ) decreased while the charge carrier density (N_d ) was increased with the thickness increase.

Study of Methyl Orange Effect on the Optical and Electrical Properties of Polystyrene (PS)

Karrar M. Ali; Nahida J.H

Engineering and Technology Journal, 2014, Volume 32, Issue 6, Pages 39-53

The present work was concerned with study of the methyl orange(MO) dye concentration effect on the optical properties ,and electrical properties of polystyrene(PS).
The samples were casted as films from the homopolymer(PS) stated above and the Dye/PS(MO/PS)composites at (3.44,6.7,and 12.5%) concentration. These prepared polymer systems were evaluated spectrophotometically. It was found increasing in absorption spectra with increasing of the dye concentration in Dye/PS composites above, which was attributed to the increasing in localized states. The results proved that the best absorption was of (12.5%MO/PS), and of the lowest energy gap was (3.15eV),The optical constant (α,k,n, εr, and εi)for the homopolymer (PS) , (Dye/PS) composites, and hybrid composites at different concentration were investigated at(λc,300nm). It was seen that there was nonlinear relationship between the optical constants and the concentration ratio, which was attributed to their incompatibility. These results were confirmed with optical micrographs. The (FTIR) spectra showed shifting, appearance ,and disappearance of new band, which was attributed to change in tacticity, geometry in the structure ,and overlapping of polymer composites band involved. The results proved that there was nonlinear relationship between the carrier concentration, mobility, fast increase in the (12.5%MO/PS, and became of order(10-6). The increase in the conductivity with dye concentration was attributed to increase of the localized states in the energy gap.