B. Kınacı

Analysis of the forward and reverse bias I-V characteristics on Au/PVA:Zn/n-Si Schottky barrier diodes in the wide temperature range

In this study, the forward and reverse bias current-voltage (I-V) characteristics of Au/Zinc acetate doped polyvinyl alcohol/n-Si Schottky barrier diodes (SBDs) have been investigated over the temperature range of 80-400 K. The values of zero-bias barrier height evaluated from forward and reverse bias I-V data, (ФBFo) and (ФBRo), increase with increasing temperature, and a discrepancy is observed between the values of ФBFo and ФBRo. Because the apparent barrier height (BH) seen from metal to semiconductor is higher than the one seen from semiconductor to metal, the obtained value of ФBFo is always greater than ФBRo value. The difference between them is almost the same as the Fermi energy level. The crossing of the experimental forward bias semilogarithmic ln I-V plots appears as an abnormality when compared to the conventional behavior of ideal SBDs. This behavior was attributed to the lack of free charge at a low temperature and could be expected in the temperature region where there is no carrier freezi...

Microstructural defect properties of InGaN/GaN blue light emitting diode structures

In this paper, we study structural and morphological properties of metal-organic chemical vapour deposition-grown InGaN/GaN light emitting diode (LED) structures with different indium (In) content by means of high-resolution X-ray diffraction, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and current–voltage characteristic (I–V). We have found out that the tilt and twist angles, lateral and vertical coherence lengths of mosaic blocks, grain size, screw and edge dislocation densities of GaN and InGaN layers, and surface roughness monotonically vary with In content. Mosaic defects obtained due to temperature using reciprocal lattice space map has revealed optimized growth temperature for active InGaN layer of MQW LED. It has been observed in this growth temperature that according to AFM result, LED structure has high crystal dimension, and is rough whereas according to PL and FTIR results, bandgap energy shifted to blue, and energy peak half-width decreased at high values. According to I–V measurements, it was observed that LED reacted against light at optimized temperature. In conclusion, we have seen that InGaN MQW structure’s structural, optical and electrical results supported one another.

Study on growth and characterizations of GaxIn1−xP/GaAs solar cell structure

GaxIn1−xP/GaAs solar cell (SC) structure was grown on p-type (100)-oriented GaAs substrate by using solid-source molecular beam epitaxy technique. The structural, optical and morphological properties of GaxIn1−xP/GaAs SC structure have been evaluated by means of high resolution X-ray diffraction, photoluminescence, spectroscopic ellipsometry and atomic force microscopy measurements at room temperature. In addition, GaxIn1−xP/GaAs SC structure was fabricated for obtaining the cell’s electrical output parameters. For this purpose, the current–voltage characteristics of GaxIn1−xP/GaAs SC structure were performed and analyzed at the room temperature under both dark and illuminations by using air mass global 1.5 (AM1.5) solar simulator. The device parameters such as the open-circuit voltage, the short-circuit current (Isc), the fill factor and the energy convertion efficiency (η) of GaxIn1−xP/GaAs SC structure were extracted from the current–voltage characteristics.

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

Abstract 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.