Electrical Properties of Al/p-Si Structures with Colchicine Organic Thin Film

In this study, we have fabricated an Al/Colchicine/p-Si structure and have investigated its current– voltage (I–V) and capacitance–voltage (C–V) characteristics at room temperature. The barrier height and ideality factor values of 0.68 eV and 3.22, respectively, have been obtained from the I-V plot. The value of the barrier height was compared with the barrier height value of 0.50 eV of a conventional Al/p-Si diode. This was attributed to the Colchicine organic film modifying the effective barrier height by affecting the space charge region of the inorganic Si semiconductor substrate. By using C – 2-V characteristics the diffusion potential value has been extracted as 1.32 V. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3514

Capacitance-conductance characteristics of Au/Ti/Al2O3/n-GaAs structures with very thin Al2O3 interfacial layer

High-k Al2O3 with metallic oxide thickness of about 3 nmon n-type GaAs substrate has been deposited by the atomic layer deposition (ALD) technique. Thus, it has been formed the Au-Ti/Al2O3/n-GaAs MIS structures. It has been seen that the MIS structure exhibits excellent capacitance-voltage (C-V) and current-voltage (I-V) properties at 300 K. The saturation current of the forward bias and reverse bias I-V characteristics was the same value. An ideality factor value of 1.10 has been obtained from the forward bias I-V characteristics. The C-Vcharacteristics of the structure have shown almost no hysteresis from +3 Vto -10 Vwith frequency as a parameter. The reverse biasC-V curves have exhibited a behavior without frequency dispersion and almost hysteresis at each frequency from 10 kHz to 1000 kHz. © 2015 IOP Publishing Ltd

Properties of Pt Schottky Type Contacts On High-Resistivity CdZnTe Detectors

In this paper we present studies of the I-V characteristics of CdZnTe detectors with Pt contacts fabricated from high-resistivity single crystals grown by the high-pressure Brigman process. We have analyzed the experimental I-V curves using a model that approximates the CZT detector as a system consisting of a reversed Schottky contact in series with the bulk resistance. Least square fits to the experimental data yield 0.78-0.79 eV for the Pt-CZT Schottky barrier height, and <20 V for the voltage required to deplete a 2 mm thick CZT detector. We demonstrate that at high bias the thermionic current over the Schottky barrier, the height of which is reduced due to an interfacial layer between the contact and CZT material, controls the leakage current of the detectors. In many cases the dark current is not determined by the resistivity of the bulk material, but rather the properties of the contacts; namely by the interfacial layer between the contact and CZT material.Comment: 12 pages, 11 figure

Broadband terahertz heterodyne spectrometer exploiting synchrotron radiation at megahertz resolution

International audienceA new spectrometer allowing both high resolution and broadband coverage in the terahertz (THz) domain is proposed. This instrument exploits the heterodyne technique between broadband synchrotron radiation and a quantum cascade laser (QCL) based molecular THz laser that acts as the local oscillator (LO). Proof of principle for exploitation for spectroscopy is provided by the recording of molecular absorptions of hydrogen sulfide (H 2 S) and methanol (CH 3 OH) around 1.073 THz. Ultimately, the spectrometer will enable to cover the 1-4 THz region in 5 GHz windows at Doppler resolution

Oral treatment with a zinc complex of acetylsalicylic acid prevents diabetic cardiomyopathy in a rat model of type-2 diabetes: activation of the Akt pathway.

BACKGROUND: Type-2 diabetics have an increased risk of cardiomyopathy, and heart failure is a major cause of death among these patients. Growing evidence indicates that proinflammatory cytokines may induce the development of insulin resistance, and that anti-inflammatory medications may reverse this process. We investigated the effects of the oral administration of zinc and acetylsalicylic acid, in the form of bis(aspirinato)zinc(II)-complex Zn(ASA)2, on different aspects of cardiac damage in Zucker diabetic fatty (ZDF) rats, an experimental model of type-2 diabetic cardiomyopathy. METHODS: Nondiabetic control (ZL) and ZDF rats were treated orally with vehicle or Zn(ASA)2 for 24 days. At the age of 29-30 weeks, the electrical activities, left-ventricular functional parameters and left-ventricular wall thicknesses were assessed. Nitrotyrosine immunohistochemistry, TUNEL-assay, and hematoxylin-eosin staining were performed. The protein expression of the insulin-receptor and PI3K/AKT pathway were quantified by Western blot. RESULTS: Zn(ASA)2-treatment significantly decreased plasma glucose concentration in ZDF rats (39.0 +/- 3.6 vs 49.4 +/- 2.8 mM, P < 0.05) while serum insulin-levels were similar among the groups. Data from cardiac catheterization showed that Zn(ASA)2 normalized the increased left-ventricular diastolic stiffness (end-diastolic pressure-volume relationship: 0.064 +/- 0.008 vs 0.084 +/- 0.014 mmHg/microl; end-diastolic pressure: 6.5 +/- 0.6 vs 7.9 +/- 0.7 mmHg, P < 0.05). Furthermore, ECG-recordings revealed a restoration of prolonged QT-intervals (63 +/- 3 vs 83 +/- 4 ms, P < 0.05) with Zn(ASA)2. Left-ventricular wall thickness, assessed by echocardiography, did not differ among the groups. However histological examination revealed an increase in the cardiomyocytes' transverse cross-section area in ZDF compared to the ZL rats, which was significantly decreased after Zn(ASA)2-treatment. Additionally, a significant fibrotic remodeling was observed in the diabetic rats compared to ZL rats, and Zn(ASA)2-administered ZDF rats showed a similar collagen content as ZL animals. In diabetic hearts Zn(ASA)2 significantly decreased DNA-fragmentation, and nitro-oxidative stress, and up-regulated myocardial phosphorylated-AKT/AKT protein expression. Zn(ASA)2 reduced cardiomyocyte death in a cellular model of oxidative stress. Zn(ASA)2 had no effects on altered myocardial CD36, GLUT-4, and PI3K protein expression. CONCLUSIONS: We demonstrated that treatment of type-2 diabetic rats with Zn(ASA)2 reduced plasma glucose-levels and prevented diabetic cardiomyopathy. The increased myocardial AKT activation could, in part, help to explain the cardioprotective effects of Zn(ASA)2. The oral administration of Zn(ASA)2 may have therapeutic potential, aiming to prevent/treat cardiac complications in type-2 diabetic patients

The effect of thermal treatment on the characteristic parameters of Ni/-, Ti/- and NiTi alloy n-GaAs Schottky diodes

Ni/-, Ti/- and NiTi alloy/n-GaAs Schottky barrier diodes (SBDs) have been fabricated and annealed for 5 min in the temperature range of 100-650 degrees C with steps of 50 or 100 degrees C. The value of Phi(b) and n for as-deposited Ni/-, Ti/- and NiTi alloy/n-GaAs SBDs has been determined to be 0.73, 0.64 and 0.68 eV and 1.02, 1.08 and 1.10, respectively. For the NiTi alloy/n-GaAs diode, while the ideality factor remains unchanged up to 400 degrees C annealing, it decreased to 1.02 at 500 degrees C. An additional barrier height enhancement with increased annealing temperature occurs while the ideality factor remains close to unity. Thermal stability of the NiTi alloy/n-GaAs diode is maintained up to an annealing temperature of 500 degrees C. It has been concluded that the NiTi alloy/n-GaAs SBD contact has a better performance than the Ni/- and Ti/n-type. (C) 1999 Elsevier Science Ltd. All rights reserved

Temperature-dependent current-voltage characteristics in thermally annealed ferromagnetic Co/n-GaN Schottky contacts

Co/n-GaN SDs has been prepared by magnetron DC sputtering technique. The Co/n-GaN SDs have annealed at 600 °C after a post-deposition. The diode parameters such as the ideality factor, barrier height and Richardson constant have been determined by thermionic emission (TE) equation within the measurement temperature range 60–320 K by the steps of 20 K in the dark. It has been seen that the parameters depend on the measurement temperature indicating the presence of a lateral inhomogeneity in the Schottky barrier. Therefore, it has been modified the experimental data by the thermionic emission (TE) mechanism with Gaussian distribution of the barrier heights by using Tung’s theoretical approach that the Schottky barrier consists of laterally inhomogeneous patches of different barrier heights. Thus, the modified Richardson plot according to Tung’s barrier inhomogeneity model [8] has given a Richardson constant of 27.66 A/(cm2 K2)

Thermal stability of NiTi alloy contacts on n-type liquid encapsulated Czochralski GaAs

The electrical characteristics of NiTi/n-GaAs Schottky barrier diodes annealed at temperatures from 100 to 300 degrees C for 5 min and from 350 to 650 degrees C for 1 min have been investigated as a function of annealing temperature, with the use of current-voltage (I-V) techniques. The Schottky barrier height Phi(b) and ideality factor n range from 0.57 eV and 1.06 for as-deposited sample to 0.84 eV and 1.06 for 450 degrees C annealing for 1 min, and 0.80 eV and 1.10 for 500 degrees C. The barrier height for these contacts increases with increasing annealing temperature. The thermal annealing proceeding has been seen to be useful for improving the electrical characteristics of NiTi evaporation on Liquid Encapsulated Czochralski (LEC) GaAs. This can be ascribed to thermal stability of the NiTi alloy/n-GaAs SBDs. The contact properties of the Schottky diodes deteriorated and became nearly ohmic above 650 degrees C for 1 min. (C) 1999 Elsevier Science Ltd. All rights reserved

The determination of the interface-state density distribution from the capacitance-frequency measurements in Au/N-Si Schottky barrier diodes

The Au/n-Si Schottky barrier diodes (SBDs) with 200-mum (sample D200) and 400-mum (sample D400) bulk thicknesses have been fabricated. The ideality factor and the barrier height have been calculated from the forward-bias current-voltage (I-V) characteristics of D200 and D400 SBDs. The energy distribution of the interface states and relaxation time are found from the capacitance-frequency (C-f) characteristics. The density of interface state and relaxation times have a (nearly constant) slow exponential rise with bias in the range of E-c -0.77 and E-c -0.47 eV from the midgap toward the bottom of the conductance band. Furthermore, the energy distribution of the interface states obtained from C-f characteristics has been compared with that obtained from the forward-bias I-V characteristics