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ZnS/p-Si heterojunction diode has been successfully fabricated by depositing the ZnS thin films on p-type Si substrates using thermionic vacuum arc technique (TVA). The structural analysis was performed with X-ray diffraction (XRD) and Atomic force microscopy (AFM). The results revealed that ZnS thin film demonstrates nano-crystalline behavior with very smooth and homogeneous surface properties. The type was determined as n-type and the carrier concentration was found approximately 3.1 +/- 10(17) cm(-3) of the ZnS thin film by means of Hall Effect measurement. The dark current-voltage (I-V) and the capacitance- voltage (C-V) measurements with different frequencies were performed to determine the characteristics of the ZnS/p-Si heterojunction diode at room temperature. I-V results show that the diode has a good rectifying characteristic with excellent rectification ratio. The electrical parameters of the diode have been obtained by using current transport mechanism. It was found that the barrier height calculated from dark I-V measurements is in good agreement with the value obtained from C-V measurements at a frequency of 1.5 MHz. The series resistance and the built in potential of the fabricated diode were calculated as 3.6 k Omega and 0.7 V using Cheung and Cheung's equation and C-V measurement, respectively. The low cost and effective film production method were utilized to fabrication of heterojunction diode and to investigate characteristics.

Among perovskite oxide materials, BaSrTiOx (BST) has attracted great attention due to its potential applications in oxide-based electronics. However, reliability and efficiency of BST thin films strongly depend on the precise knowledge of the film microstructure, as well as optical and electrical properties. In the present work, BST films were deposited at room temperature using radio frequency magnetron sputtering technique. The impact of deposition pressure, partial oxygen flow, and post-deposition annealing treatment on film microstructure, surface morphology, refractive index, and dielectric constants were studied by X-ray diffraction, scanning electron microscopy, spectrophotometry, ellipsometry, photoluminescence, as well as capacitance-voltage measurements. Well-adhered and uniform amorphous films were obtained at room temperature. For all as-deposited films, the average optical transmission was similar to 85% in the VIS-NIR. spectrum. The refractive indices of BST films were in the range of 1.90-2.07 (lambda = 550 nm). Post-deposition annealing at 800 degrees C for 1 h resulted in polycrystalline thin films with increased refractive indices and dielectric constants, however reduced optical transmission values. Frequency dependent dielectric constants were found to be in the range of 46-72. However, the observed leakage current was relatively small, about 1 mu A. The highest FOM values were obtained for films deposited at 0.67 Pa pressures, while charge storage capacity values increased with increased deposition pressure. Results show that room-temperature grown BST films have potential for device applications.

In the present work, we report a novel citrate-selective sensor based on iron (III) phthalocyanine chloride-C-monoamido-Poly-n-Butyl Acrylate (Fe(III)MAPcCl-P-n-BA) modified silicon nitride and Ion sensitive field effect transistor (ISFET) structures for the electrochemical determination and estimation of the pathophysiological range of citrate. The developed capacitive sensor based on Fe(III)MAPcCl-P-n-BA had a Nernstian sensitivity of (−20.2 ± 1.3) mV/decade with a detection limit of about 7 × 10 −7 M and a linear range from 10 −6 M to 10 −1 M (RSD = 6.2%). Then, the performance of the Fe(III)MAPcCl-P-n-BA functionalized ISFET structure towards the detection of citrate has been investigated. A Nernstian sensitivity of about (−19.8 ± 1.0) mV/decade in the range from 10 −6 M to 10 −1 M was achieved (RSD = 4.8%) which covered the pathologically important clinical range of citrate. The detection limit was about 4 × 10 −7 M. The number of available recognition sites N s and the complexation constant pK were calculated using the enhanced site binding model. A side by side comparison of the developed chemical sensors based on electrolyte-insulator-Semi conductor (EIS) and ISFET structures showed similar characteristics which proves the successful miniaturization of the semiconductor based transducer. The obtained experimental data of the Fe(III)MAPcCl-P-n-BA functionalized ISFET structure were used to validate the TopSPICE ISFET/MEMFET macromodel. The obtained theoretical sensitivity was in good agreement to the experimental one which proves the successful design of the developed ISFET/MEMFET macromodel.

The purpose of this study is to investigate the usability of ytterbium oxide (Yb2O3) as a sensitive region/gate oxide in metal oxide semiconductor (MOS) based dosimeters and to determine the advantages and disadvantages of this device relative to its alternatives. For this purpose, amorphous Yb2O3 films were grown on p type Si by radio-frequency magnetron sputtering and aluminum (Al) was used as front and back ohmic contacts of the capacitor. Yb2O3 MOS devices were irradiated incrementally to the total dose of 70 Gy by Co-60 radioactive source. The capacitance-voltage measurements were performed at low (100 kHz) and high (1 MHz) frequencies to examine the behavior of the traps. The sensitivity of the device for 70 Gy was obtained using flat band voltage shifts as 27.5 +/- 1.1 and 28.1 +/- 1.3 mV/Gy for 100 kHz and 1 MHz, respectively. The changes in the oxide trap charge densities in the studied dose between 0.5 and 70 Gy are in the ranges of (1.09 +/- 0.04) x 10(11)-(1.23 +/- 0.05) x 10(12) cm(-2) for 100 kHz and (-3.26 +/- 0.08) x 10(10)-(8.16 +/- 0.35) x 10(11) cm(-2) for 1 MHz. For both frequencies, there was no significant change in the interface trap charge densities over the applied dose and the density of these traps remained in order of 10(11) cm(-2) after each applied dose. The percentage fading were measured at only 1 MHz for evaluation of the device's dose storage capacity and the results varied from 4% (5 min) to -19% (50 min). An almost constant fading value was obtained after 20 min from irradiation. The capacitor's sensitivity was found to be higher than those of similar devices composed of HfO2, La2O3, SiO2, Sm2O3, and Y2O3. Yb2O3 would be a promising candidate for a new generation of MOS based radiation sensors. Türkiye Cumhuriyeti Kalkınma Bakanlığı - 2016K121110 Abant İzzet Baysal Üniversitesi - AIBU, BAP -.2014.03.02.765

Porous GaN crystals have been successfully grown and electrically contacted simultaneously on Pt- and Au-coated silicon substrates as porous crystals and as porous layers. By the direct reaction of metallic Ga and NH(3) gas through chemical vapor deposition, intermetallic metal-Ga alloys form at the GaN-metal interface, allowing vapor-solid-solid seeding and subsequent growth of porous GaN. Current-voltage and capacitance-voltage measurements confirm that the intermetallic seed layers prevent interface oxidation and give a high-quality reduced workfunction contact that allows exceptionally low contact resistivities. Additionally, the simultaneous formation of a lower workfunction intermetallic permits ohmic electron transport to n-type GaN grown using high workfunction metals that best catalyze the formation of porous GaN layers and may be employed to seed and ohmically contact a range of III-N compounds and alloys for broadband absorption and emission.

A description of the calculation of the cross-section for the atomic displacement σ by energetic electrons, versus penetration depth x, is given. Curves of σ(x) computed for various values of the threshold energy for displacement are given in the case of silicon. The profiles of the concentration of the defects introduced by electron irradiation of various energies in silicon is determined from capacitance-voltage measurements on gold-silicon Schottky diodes. The measurement of the defect creation rates at zero depth gives 20.5 ± 1 eV for the threshold energy.