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41.
In this study, the forward bias current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the Al/TiO2/p-Si (MIS) structures derived using the sol–gel method have been investigated and compared at various preparation temperatures.
Experimental results show that the preparation temperatures strongly affect the electrical characteristics, such as ideality
factor (n), zero-bias barrier height (), series resistance (R
s
) and interface states (N
ss
). The MIS structures show non-ideal behavior of I–V characteristics with an n varying between 2.17 and 4.61. We have found that the and R
s
increase as the n decrease with increasing preparation temperature. The energy distribution profile of N
ss
of the Al/TiO2/p-Si (MIS) structures was obtained from the forward bias I–V characteristics by taking into account both the bias dependence of the effective barrier height () and R
s
for various preparation temperatures. The values of N
ss
increase from the midgap towards the top of valance band for various preparation temperatures. 相似文献
42.
N. Serin 《Applied Physics A: Materials Science & Processing》1985,36(4):209-212
We developed a method for the determination of the minority carrier diffusion coefficient by means of the capacitance-voltage characteristics of a Schottky barrier. Capacitance-voltage-frequency characteristics were measured at room temperature and liquid nitrogen temperature. We adapted the diffusion capacitance concept ofp-n junction for the metal/semiconductor rectifier contact. We determined the minority carrier diffusion coefficient as 47–61 cm2/s. 相似文献
43.
This study investigated the effect of the substrate temperature on the structural, optical, morphological, and electrical properties of undoped SnO2 films prepared by a spray deposition method. The films were deposited at various substrate temperatures ranging from 300-500 °C in steps of 50 °C and characterized by different optical and structural techniques. X-ray diffraction studies showed that the crystallite size and preferential growth directions of the films were dependent on the substrate temperature. These studies also indicated that the films were amorphous at 300 °C and polycrystalline at the other substrate temperatures used. Infrared and visible spectroscopic studies revealed that a strong vibration band, characteristic of the SnO2 stretching mode, was present around 630 cm−1 and that the optical transmittance in the visible region varied over the range 75-95% with substrate temperature, respectively. The films deposited at 400 °C exhibited the highest electrical conductivity property. 相似文献
44.
Azo compounds were prepared by the reaction between benzenediazonium chloride and 4-amino-5-hydroxy-2,7-naphthalenedisulfonic
acid monosodium salt under alkaline conditions. Two new azo-linked Schiff base ligands, 4-(3-methoxysalicylidene)-5-hydroxy-6-(2-hydroxyphenylazo)-2,7-naphthalene
disulfonic acid disodium salt (H2L) and 4-(3-methoxysalicylidene)-5-hydroxy-6-(2-hydroxy-4-cholorophenylazo)-2,7-naphthalenedisulfonic acid disodium salt (H2L1), have been synthesized. Also, the new CuII, NiII and CoII complexes of the azo-linked Schiff base ligands were prepared and characterized by infrared spectra, UV–Vis, 1H- and 13C-n.m.r., attached proton test (APT) and distortionless enhancement by polarization transfer (DEPT) and atomic absorption
spectroscopy, mass spectrocopy, elemental analyses, thermogravimetric analysis, conductivity and magnetic measurements. It
was determined that the synthesized ligands were comprised of six-membered rings due to intramolecular hydrogen bonding. The
results suggested that condensation of the azo-derivative compounds and o-vanillin in a 1:1 molar ratio produces mononuclear Schiff base ligands with an ONO donor set. Preliminary histological studies
were made. Magnetic moment studies showed that all complexes have a tetrahedral configuration. 相似文献
45.
Aybegül Gölcü Mustafa Dolaz Havva Demirelli Metin Diðrak Selahattin Serin 《Transition Metal Chemistry》2006,31(5):658-665
The complexation processes between CuII and the antiviral drug, valacyclovir hydrochloride (H2L), were studied under different reaction conditions, using UV-Vis, IR and mass spectra, magnetochemical, thermogravimetric,
atomic absorption, conductivity, and elemental analysis data. Using the Job method, the compositions of these complexes were
determined. Under the ligand (H2L) excess (M:L = 1:1–1:10). In aqueous solutions, a binuclear violet complex Cu2(HL)2L(H2O)4 is formed, with an octahedral structure. Under comparable amounts of the reagents, in MeOH solutions, a green mononuclear
complex Cu(H2L)Cl2 is formed. Protonation constants of the H2L, and stability constants of its Cu2+ complexes, were determined by potentiometric titration in H2O media at 25 ± 0.02 °C under a N2 atmosphere and ionic strength of 0.1 m NaCl. It has been observed that H2L has three protonation constants. The divalent metal ion Cu2+ forms stable 2:1 and 2:2 complexes with H2L. The antimicrobial activity studies of the valacyclovir and it’s complexes have been studied against some gram positive
species: (Corynebacterium xerosis, Bacillus brevis, Bacillus megaterium, Bacillus cereus, Mycobacterium smegmatis, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis) and gram negative (Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Yersinia enterocolitica, Kluyveromyces fragilis, Saccharomyces cerevisiae, Candida albicans) bacteriaz. 相似文献
46.
Mükerrem Kurtoğlu Esin İspir Nurcan Kurtoğlu Sevil Toroğlu Selahattin Serin 《Transition Metal Chemistry》2005,30(6):765-770
A new tetraoxime ligand, (2E, 3E, 9E, 10E)-1, 4, 8, 11-tetraazacyclotetradecane-2, 3, 9, 10-tetrone tetraoxime has been prepared by the template condensation of 1,3-propanediamine and cyanogen-di-N-oxide, obtained by treating (E, E)-dichloroglyoxime in CH2Cl2 with Na2CO3 at −10 °C. The coordination chain polymers {[(pnngH2)2Ni]n (5) and [(pncgH2)2Cu]n(6)} of two transition metal ions, [Ni(II) and Cu(II)] with the vic-dioxime ligand have been prepared. The oxime ligand acts as a polydentate ligand bending through nitrogen atoms in the presence of a base, as do most of the vic-dioximes. In the complexes, the chloride ions coordinate to the nickel and copper ions. The structures of these novel vic-dioxime compounds are proposed on the basis of the elemental analyses, molar conductance data, i.r., and U.v.–visible are presented. Elemental analyses indicate a ligand metal ratio of 1:1 in the coordination polymers. Conductivity measurements have shown that mono- and polynuclear complexes are non-electrolytes. In addition, anti-microbial activities of the compounds have been investigated. 相似文献
47.
Brousmiche DW Serin JM Fréchet JM He GS Lin TC Chung SJ Prasad PN 《Journal of the American Chemical Society》2003,125(6):1448-1449
A novel fluorescence resonance energy transfer (FRET) system containing a two-photon absorbing dye and a nile red chromophore has been synthesized. Upon two-photon excitation by laser at 815 nm this molecule displays efficient energy transfer from the two-photon absorbing dye to the nile red moiety, with an 8-fold increase in emission compared to the model compound. Similarly, single-photon excitation of the two-photon absorbing moiety at 405 nm results in >99% energy-transfer efficiency, along with a 3.4-fold increase in nile red emission compared to direct excitation of the nile red chromophore at 540 nm. This system provides an effective way to use IR radiation to excite molecules that, by themselves, have little or no two-photon absorption. 相似文献
48.
Dichtel WR Serin JM Edder C Fréchet JM Matuszewski M Tan LS Ohulchanskyy TY Prasad PN 《Journal of the American Chemical Society》2004,126(17):5380-5381
A new approach to two-photon excited photodynamic therapy has been developed. A dendritic array of eight donor chromophores capable of two-photon absorption (TPA) was covalently attached to a central porphyrin acceptor. Steady-state fluorescence measurements demonstrated that the donor chromophores transfer excited-state energy to the porphyrin with 97% efficiency. Two-photon excitation of the donor chromophores at 780 nm resulted in a dramatic increase in porphyrin fluorescence relative to a porphyrin model compound. Enhanced singlet oxygen luminescence was observed from oxygen-saturated solutions of the target compound under two-photon excitation conditions. 相似文献
49.
Temperature-dependent conductivity and thermopower measurements are carried out for undoped and In-doped CuO thin films. We investigate the effects of In-doping on carrier transport properties of CuO thin films in the temperature range of 300?<?T?<?400?K. Carrier transport is dominated by simple thermally activated conduction in the undoped film. On the other hand, small polarons play an essential role in the carrier transport properties in the In-doped films. By increasing the In content, the conduction behaviour transits from adiabatic limit to the non-adiabatic limit, and the conductivity decreases. 相似文献
50.