Computationally efficient quantum-mechanical technique to calculate direct tunnelling gate leakage current in metal-oxide-semiconductor structures

We propose a computationally efficient, accurate and numerically stable quantum- mechanical technique to calculate the direct tunneling (DT)gate current in metal-oxide-semiconductor (MOS) structures. Knowledge of the imaginary part G of the complex eigenenergy of the quasi-bound inversion layer states is required to estimate the lifetimes of these states. Exploiting the numerically obtained exponential dependence of G on the thickness of the gate-dielectric layer even in the sub-1-nm-thickness regime, we have simplified the determination of G in devices where it is too small to be calculated directly. It is also shown that the MOS electrostatics, calculated self-consistently with open boundary conditions, is independent of the dielectric layer tickness provided that the other parameters remain unchanged. Utilizing these findings, a computationally efficient and numerically stable method is developed for calculating the tunneling current–gate voltage characteristics. The validity of the proposed model is demonstrated by comparing simulation results with experimental data. Sample calculations for MOS transistors with high-K gate-dielectric materials are also presented. This model is particularly suitable for DT current calculation in devices with thicker gate dielectrics and in device or process characterization from the tunneling current measurement

Gate Capacitance of deep submicron MOSFETS with high-K gate dielectrics

We study gate capacitance of deep submicron MOSFETs with high-K gate dielectrics. Schrödinger’s equation is solved by applying an open boundary condition at silicon-gate dielectric interface. Self-consistent numerical results reveal that accounting for wave function penetration into the gate dielectric causes the carrier distribution to be shifted closer to the gate dielectric. This effect increases with increasing gate voltage and also increases with the decreasing conduction band offset of the gate dielectric material with silicon. Gate capacitance calculated from conventional modeling is found to be independent of dielectric materials for a given equivalent oxide thickness (EOT). But our study shows that when wave function penetration into the gate dielectric is considered, gate capacitance for a given EOT increases with a decrease in the conduction band offset. Effects of substrate doping density on gate capacitance are found to be negligible when wave function penetration effects are incorporated

Effects of neglecting carrier tunneling on electrostatic potential in calculating direct tunneling gate current in deep submicron MOSFETs

We investigate the validity of the assumption of neglecting carrier tunneling effects on self-consistent electrostatic potential in calculating direct tunneling gate current in deep submicron MOSFETs. Comparison between simulated and experimental results shows that for accurate modeling of direct tunneling current, tunneling effects on potential profile need to be considered. The relative error in gate current due to neglecting carrier tunneling is higher at higher gate voltages and increases with decreasing oxide thickness. We also study the direct tunneling gate current in MOSFETs with high- gate dielectrics

Contribution of morpho-physiological attributes in determining the yield of mungbean

Field experiments were conducted in 2006 and 2007 under subtropical conditions to investigate the variations in growth and reproductive characters, and yield attributes for selection of important source and sinks characters using correlation and path coefficient analyses in 45 mungbean genotypes. Large genetic variability existed in source characters viz., leaf area index (LAI) (1.22 to 3.80) and sink characters viz., number of racemes plant-1 (6.30 to 22.9), flowers plant-1 (18.1 to 51.9) and pods plant-1 (9.6 to 22.1). Genotypic correlation study revealed that among the traits investigated, LAI was the most important source that determined total dry mass (TDM) yield, and reproductive characters like number of racemes, flowers and pods plant-1 were the most important sinks that determined seed yield. Contrarily, reproductive efficiency (RE, % pod set to opened flowers) did not show significant relationship with pod number and seed yield, indicating that selection of high yield based on RE may be misleading. Path coefficient analysis further revealed that number of flowers, pods and 100-seed weight constituted central important sinks which exerted direct positive influence on seed yield. The results indicated that pod yield could be increased by increased raceme and flower production, while seed yield could be increased by increasing pod production. High yielding genotypes, in general, possessed higher earlier mentioned source (LAI) and sink (flower and pod number) characters which resulted in higher seed yield in mungbean. This information could be exploited in the future plant breeding programmes.Key words: Source-sink, correlation, path analysis, mungbean

Drain current multiplication in thin pillar vertical MOSFETs due to depletion isolation and charge coupling

Drain current multiplication in vertical MOSFETs due to body isolation by the drain depletion region and gate–gate charge coupling is investigated at pillar thicknesses in the range of 200–10 nm. For pillar thickness >120 nm depletion isolation does not occur and hence the body contact is found to be completely effective with no multiplication in drain current, whereas for pillar thicknesses <60 nm depletion isolation occurs for all drain biases and hence the body contact is ineffective. For intermediate pillar thicknesses of 60–120 nm, even though depletion isolation is apparent, the body contact is still effective in improving floating body effects and breakdown. At these intermediate pillar thicknesses, a kink is also observed in the output characteristics due to partial depletion isolation. The charging kink and the breakdown behavior are characterized as a function of pillar thickness, and a transition in the transistor behavior is seen at a pillar thickness of 60 nm. For pillar thickness greater than 60 nm, the voltage at which body charging occurs decreases (and the normalized breakdown current increases) with decreasing pillar thickness, whereas for pillar thickness less than 60 nm, the opposite trend is seen. The relative contributions to the drain current of depletion isolation and the inherent gate–gate charge coupling are quantified. For pillar thickness between 120 and 80 nm, the rise in the drain current is found to be mainly due to depletion isolation, whereas for pillar thicknesses <60 nm, the increase in the drain current is found to be governed by the inherent gate–gate charge coupling

Characterization of Two Historical Postage Stamps Made from Cotton Fibers and Their Restoration Trials Based on the Experimental Studies

This is the final version. Available on open access from Hindawi via the DOI in this recordData Availability: The data used to support the findings of this study are included within the article.Ancient stamps are suffering from the destructive effects of different kinds of inks that were prepared from different ingredients. Two Egyptian historical postage stamps printed in blue and red printing inks were evaluated and examined for their composition using a light microscope, SEM-EDS, FTIR, and Raman spectroscopic analyses. Mechanical, chemical, and deacidification treatments were done for the two stamps. Model stamps were made from the cotton pulp in the book house to simulate historical stamp paper with an average thickness of 11 microns. The unprinted and printed paper samples with printing inks that aged and unaged were treated with 0.7% Klucel G, 0.2% TiO2 NP, or a mixture of 0.7% Klucel G + 0.2% TiO2 NP, and the color change was measured and compared with the blank samples. The two stamps are suffering from high pH, where the margin color of the stamps changed to yellow-brown with weakness of the stamp paper. By SEM examination, stamps have suffered from fibers’ weakness and dryness resulting from the self-oxidation reactions. EDS elemental composition of the red stamp showed the presence of C, O, Na, Al, Si, Mg, S, Ca, Ba, and Fe, while in the blue stamp, it was C, O, Na, Al, Si, P, S, Cl, and Ca. Raman spectrometer wavelengths turn out that the blueprinting ink of the stamp was characterized with spectra of ultramarine blue (lazurite), while hematite was characterized by the red stamp. FTIR analysis for the printing inks identified that gum Arabic sample and linseed oil were the binding and color medium, respectively. From the model trials, it was observed that the treatment of a mixture of Klucel G and TiO2 NP had the best properties for the consolidation of stamps. The two historical stamps were documented through different spectroscopic analyses, and from the restoration trials, it was observed that the mixture of 7% Klucel G + 0.2% TiO2 NP appeared to be a new and effective method for recovering the historical postage stamps.King Saud University, Riyadh, Saudi Arabi