Current-voltage (I-V) characteristics of Au/InGaAs/n-GaAs Schottky barrier diodes

In this study, the forward and reverse bias current-voltage (I-V) characteristics of Au/InGaAs/n-GaAs Schottky barrier diodes (SBDs) have been investigated at room temperature. InGaAs epilayer was grown on (100) oriented n-GaAs substrate using V80-H solid source Molecular Beam Epitaxy (MBE) system. Atomic Force Microscope (AFM) was used in order to study the surface properties of InGaAs epilayer. The AFM measurement was performed by using an Omicron variable temperature STM/AFM instrument. The electrical parameters such as barrier height (Phi(b)), ideality factor (n), series resistance (R-s) and interface states (N-ss) of Au/InGaAs/n-GaAs SBDs have been calculated by using forward and reverse bias I-V measurements. The energy distribution of interface states of the structure was obtained from the forward bias I-V measurements by taking the bias dependence of the effective barrier height (Phi(e)) into account. In addition, the values of R-s and Phi(b), were determined by using Cheung's methods and results have been compared with each other.State of Planning Organization of TurkeyTurkiye Cumhuriyeti Kalkinma Bakanligi [2011K120290]This work is supported by the State of Planning Organization of Turkey under Grant no. 2011K120290WOS:0003025803000742-s2.0-8486014571

Comparison of nanofiltration and adsorption techniques to remove arsenic from drinking water

Arsenic occurs naturally in the ground and surface water and is not desired in the drinking water due to carcinogenic effect on human body. The common types of arsenic are arsenate (As V) and arsenite (As III). Although arsenate removal has been achieved by membranes, adsorption, ion exchange and coagulation, arsenite removal is difficult to decrease the concentration up to the standard level (below to 10 mu g/L). In this study, nanofiltration (NF) and adsorption techniques have been compared to remove arsenite from drinking water. In nanofiltration study, different NF membranes and arsenite feed concentrations have been Studied. Feed water was prepared synthetically and laboratory scale cross-flow mode filtration apparatus with a flat-sheet membrane cell was used for NF experiments. In the adsorption experiments with granular iron hydroxide (GIH), all studies were performed in the free water flow and at the normal pH of tap water. It was concluded that arsenite concentration was lowered to below 1.0 mu g/L with adsorption. These results showed that GIH adsorption can be used to remove arsenite concentration of 0.1 and 0.5 g/L from water supplies

Preparation of RF sputtered AZO/Au thin film hydrogen peroxide sensitive electrode for utilization as a biosensor

In this study, hydrogen peroxide (H2O2) sensitive Al doped ZO(AZO)/Au thin film electrode has been developed for the utilization as a biosensor. A preferred c-axis oriented AZO/Au thin film was deposited on quartz substrate by RF magnetron sputtering at room temperature. Structural, morphological and optical properties of the AZO film were analyzed by X-ray diffraction, atomic force microscopy and photoluminescence. The sensor performance was characterized by electrochemical analysis device. The sensibility of prepared thin film electrodes to H2O2 was studied. The dependence of amperometric response current on the glucose and cholesterol concentrations was also investigated.WOS:0003371679000482-s2.0-8490254806

The effect of thickness on surface structure of rf sputtered TiO<inf>2</inf> thin films by XPS, SEM/EDS, AFM and SAM

In the current study, silicon was utilized as the substrate material and, then, the TiO2 depositions with 100 nm, 300 nm, 500 nm and 700 nm were done onto substrates as thin films at room temperature by a radio frequency (rf) magnetron sputtering method. The binding energy, the surface roughness, elemental analysis and the specific acoustic impedance have been determined via X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and scanning acoustic microscopy (SAM), respectively. AFM analysis represented that the root mean square roughness values changed in the range of 0.72 nm-1.22 nm, gradually by the increase in thickness. Two-dimensional acoustic images were recorded by SAM with 80 MHz transducer. The mean and standard deviation values of acoustic impedance were found as 3.151 +/- 0.080 MRayl for 100 nm, 3.366 +/- 0.080 MRayl for 300 nm, 3.379 +/- 0.067 MRayl for 500 nm and, 3.394 +/- 0.065 MRayl for 700 nm. SAM results pointed out that the hardness of films increased with increasing thickness. Moreover, the surface defects at the micrometer level were demonstrated. The success of imaging films indicated the potential of SAM in monitoring as well as the inspection of flat two-dimensional surfaces