Role of the radio frequency magnetron sputtered seed layer properties on ultrasonic spray pyrolyzed ZnO thin films

Rujisamphan, Nopporn/0000-0001-9362-4370; Onuk, Zuhal/0000-0003-3042-6494WOS: 000413807200026Herein, we investigated structural and electrical properties of ultrasonic spray pyrolyzed ZnO thin films (ZnO (USP)) deposited on radio frequency sputtered ZnO nanocolumns (ZnO(Seed)) under various oxygen atmosphere on p-Si substrates. X-ray diffraction data of the samples showed that the samples had a hexagonal structure with a strong (002) preferred orientation. the grain size of ZnO(USP) samples prepared on the seed layer sputtered in 25% and 50% oxygen atmosphere decreased and surface morphology was nanopebbles. ZnO samples prepared on the seed layers exhibited sharp and predominant ultraviolet luminescence at approximately 380 nm. the current-voltage characteristics of the n-ZnO(USP)/n-ZnO(seed)/p-Si heterojunctions were significantly affected by the seed layer preparation conditions. Backward diode behavior was observed for the n-ZnO(USP)/n-ZnO (seed)/p-Si heterojunctions with high donor concentration, in which the seed layers prepared in 100% and 75% argon atmosphere. the carrier concentration value was decreased for the films with the seed layer, obtained at higher oxygen content in the sputtering atmosphere.research fund of Recep Tayyip Erdogan University, Rize, TurkeyRecep Tayyip Erdogan University [2014.102.01.02]This work was supported by the research fund of Recep Tayyip Erdogan University, Rize, Turkey, under Contract No. 2014.102.01.02. N.R. would like to acknowledge the Theoretical and Computational Science (TaCS) Center under Computational and Applied Science for Smart Innovation Research Cluster (CLASSIC), Faculty of Science, KMUTT

Controllable growth and characterization of highly aligned ZnO nanocolumnar thin films

Rujisamphan, Nopporn/0000-0001-9362-4370; Onuk, Zuhal/0000-0003-3042-6494WOS: 000391418200033We investigated the effects of growth conditions during magnetron sputtering on the structural, morphological, and optical properties of nanostructured ZnO thin films. Undoped ZnO thin films are deposited onto p-type Si (100) and corning 7059 glass substrates by RF magnetron sputtering using a ZnO target in combination with various Ar-O-2 sputtering gas mixtures at room temperature. the effect of the partial pressure of oxygen on the morphology of ZnO thin film structure and band alignment were investigated. Thickness, and therefore the growth rate of the samples measured from the cross-sectional SEM micrographs, is found to be strongly correlated with the oxygen partial pressure in the sputtering chamber. the optical transmittance spectrometry results show that the absorption edge shifts towards the longer wavelength at higher oxygen partial pressure. X-ray photoelectron spectroscopy (XPS) used for determining the surface chemical structure and valence band offsets show that conduction band can be controlled by changing the sputtering atmosphere. (C) 2016 Elsevier B.V. All rights reserved.Theoretical and Computational Science (TaCS) Center, Bangkok, ThailandThe authors would like to thank Dr. Hassnain Jaffari and Dr. Inci Ruzybayev for helpful discussions. N.R. acknowledges the support from the Theoretical and Computational Science (TaCS) Center, Bangkok, Thailand

Parametric simulation of hybrid nanofluid flow consisting of cobalt ferrite nanoparticles with second-order slip and variable viscosity over an extending surface

This study explores the unsteady hybrid nanofluid (NF) flow consisting of cobalt ferrite (CoFe2O4) and copper (Cu) nano particulates with natural convection flow due to an expanding surface implanted in a porous medium. The Cu and CoFe2O4 nanoparticles (NPs) are added to the base fluid water to synthesize the hybrid NF. The effects of second-order velocity slip condition, chemical reaction, heat absorption/generation, temperature-dependent viscosity, and Darcy Forchheimer are also assessed in the present analysis. An ordinary differential equation system is substituted for the modeled equations of the problem. Further computational processing of the differential equations is performed using the parametric continuation method. A validation and accuracy comparison are performed with the Matlab package BVP4C. Physical constraints are used for presenting and reviewing the outcomes. With the increase in second-order velocity slip condition and unsteady viscosity, the rates of heat and mass transition increase significantly with the variation in Cu and Fe2O4 NPs. The findings suggest that the uses of Cu and Fe2O4 in ordinary fluids might be useful in the aerodynamic extrusion of plastic sheets and extrusion of a polymer sheet from a dye