Immunobiological properties of selected natural and chemically modified phenylpropanoids

Effects of natural and structurally transformed lignans compared with stilbenes or stilbenoids on production of nitric oxide (NO) triggered by lipopolysaccharide (LPS) and interferon-γ (IFN-γ), tested under in vitro conditions using murine resident peritoneal macrophages, are reviewed. Relation between the molecular structure and immunobiological activity was investigated, and implication of substituents, double bond stereochemistry, or cyclic attachments (double bond geometry fixation) was assessed. The focus was on lignans and stilbenoids because they were originally selected for a joint project of common interest to phytochemical and pharmacological investigation and because they represent well interesting and universally attractive groups of polyphenols with a feasible potential for therapeutic or nutraceutic utilization

Trap-Assisted Tunneling in the Schottky Barrier

The paper presents a new way how to calculate the currents in a Schottky barrier. The novel phenomeno-logical model extends the Shockley-Read-Hall recombi-nation-generation theory of trap-assisted tunneling. The proposed approach explains the occurrence of large leakage currents in Schottky structures on wide band semi-conductors with a high Schottky barrier (above 1 eV) and with a high density of traps. Under certain conditions, trap-assisted tunneling (TAT) plays a more important role than direct tunneling

Properties of the Si-SiO2 interfaces in MOS structures with nitrogen doped silicon

The article presents the results of capacitance measurements on MOS structures with a silicon substrate that was doped by nitrogen during the growth of the single crystal by Czochralski’s method. Attention is paid to the energy distribution of the trap density at the Si-SiO2 interface. The effect of the bond of nitrogen and oxygen brought about a slight increase in the trap density with a typical distribution of energy maxima of the deep levels in the forbidden band of Si

Radiation Hardness of Mos Structures Exposed to High-Energy Ions

MOS structures exposed to 305 MeV Kr and 710 MeV Bi ions irradiation with fluences of 109 cm2 and 1010 cm2 were investigated by capacitance measuring methods (C-V, C-t), completed by quasistatic low-frequency C-V and DLTS measurements.The irradiated MOS structures were functional in spite of a high density of radiation defects. The electric activity of the defects brought a sharp decrease in the generation parameters tr and g. The parameters of six deep levels were detected in the MOS structures exposed to 710 MeV Bi ions irradiation. Five of these levels with energies 0.52 eV, 0.14 eV, 0.17 eV, 0.25 eV, 0.27 eV were radiation defects

Defect Analysis of Pentacene Diode

This paper demonstrates the analysis of defect states in pentacene film sandwiched between Au and Al electrodes by the deep-level transient spectroscopy method. Three hole-like deep energy levels were observed. The effective mass obtained from the simulation is applied and defect parameters, namely the capture cross-sections and the activation energy 3.7 × $10^{-18} cm^2$ at 0.34 eV, 3.1 × $10^{-17} cm^2$ at 0.41 eV, and 2.9 × $10^{-15} cm^2$ at 0.63 eV is determined from the Arrhenius plot. Reliability of obtained defect parameters is confirmed by simulation of deep level transient spectra and comparison with experiment

Simulation of electrical parameters for Ru/Ta2O5/SiO2/Si(p) high-k MOS structure

The contribution presents the results of simulation of direct tunnelling of free charge carriers through a thin gate insulator in MOS structures consisting of a Ta2O5/SiO2 bilayer taking into account also indirect tunnelling of free charge carriers through the SiO2/Si interface traps. The calculated I–V and C–V curves reveal the processes of electron and hole tunnelling through the insulator-to-semiconductor potential barrier that can be divided into four classes

Deep energy levels in RuO2/4H–SiC Schottky barrier structures

RuO2/4H–SiC Schottky diode structures based on n-type 4H–SiC (7×1017 cm–3) with stoichiometric RuO2 Schottky contacts were characterized by electrical capacitance-voltage and current voltage methods and deep-level transient spectroscopy in order to determine their unique semiconducting and electronic properties. The RuO2 films exhibited electrical conductivity of 60 µ cm for Schottky barrier heights of approximately 0.88 eV. These Schottky structures revealed two deep energy levels with thermal activation energies of 0.56 and 0.85 eV with reference to the conduction band.published_or_final_versio