Modulation Extrinsic photoconductivity spectra between 1.44eV and 1.75eV of unintentionally n-doped high resistance GaN film grown by MOCVD are measured at room temperature by using wavelength adjustable Ti:Sapphire l...
Modulation Extrinsic photoconductivity spectra between 1.44eV and 1.75eV of unintentionally n-doped high resistance GaN film grown by MOCVD are measured at room temperature by using wavelength adjustable Ti:Sapphire laser. We find that there are two major deep levels in the GaN material in the used photon energy range. The relaxation time of excess carriers controlled by those levels are in the order of 10−4sec. The concentration of localized states are determined as 1.8×108cm−3 and 2.5×109cm−3, respectively. A physical model is developed to explain the results and process the data. Using a new method we have determined the optical absorption cross section of deep levels are 1.5×10−17cm2 and 2.7×10−18cm2, respectively.
In this paper we employed the TSC method to investigate the traps in GaN. The measured sample was a M-S-M UV-detector of high-resistance GaN on sapphire grown by LP-MOCVD. The relation of dark conductance to temperatu...
In this paper we employed the TSC method to investigate the traps in GaN. The measured sample was a M-S-M UV-detector of high-resistance GaN on sapphire grown by LP-MOCVD. The relation of dark conductance to temperature clearly showed three major donor levels at 0.019, 0.13 and 0.74eV respectively. TSC measurements from 60 to 380K indicated that there were at least 11 traps in the GaN material. The active energy of those traps were 0.15, 0.19, 0.25, 0.28, 0.33, 0.39, 0.47, 0.55, 0.60, 0.63 and 0.67eV. The range of trap density is from 6 × 1014cm−3 to 2 × 1018cm−3. By comparing TSC spectrum to dark current, we consider there are at least 4 hole traps in the measured range with energy of 0.25, 0.28, 0.33 and 0.39eV. The illumination time effect was studied and discussed.
In multivariate statistical monitoring, batch process models should well reflect process characteristics in order to achieve satisfactory fault detection results. In manufacturing systems, many batch processes are inh...
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In multivariate statistical monitoring, batch process models should well reflect process characteristics in order to achieve satisfactory fault detection results. In manufacturing systems, many batch processes are inherently multiphase. Usually, process features are different from one phase to another, and gradual transitions are often observed between phases. Another important characteristic of batch processes is uneven operation durations. In multiphase batch processes, not only the entire batch durations but also the phase durations may be unequal from batch to batch. In this paper, the Gaussian mixture model (GMM) method is adopted to solve both the multiphase and the uneven-duration problems simultaneously. A benchmark penicillin fermentation process is utilized to verify the phase division, transition identification and process monitoring results based on the proposed method.
Colloids near the glass concentration are often taken as models for molecular glasses. Yet, an important aspect of the dynamics of molecular glasses, structural recovery, has not been elucidated in colloids. We take a...
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Colloids near the glass concentration are often taken as models for molecular glasses. Yet, an important aspect of the dynamics of molecular glasses, structural recovery, has not been elucidated in colloids. We take advantage of a thermosensitive colloidal suspension to study the structural recovery after concentration jumps by using diffusing wave spectroscopy. The three classical aging signatures observed in molecular glasses are studied and the results are compared with those typical of molecular glasses. For the intrinsic isotherms, unlike molecular glasses, the colloid shows huge changes in relaxation time at equilibrium while the times required to reach the equilibrium state are nearly constant. For asymmetry of approach, we find a similar nonlinearity to that observed in the molecular glasses. For the memory experiment, while a memory effect is seen, the response is qualitatively different from that in molecular glasses.
We show that a fluid under strong spatially periodic confinement displays a glass transition within mode-coupling theory at a much lower density than the corresponding bulk system. We use fluctuating hydrodynamics, wi...
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We show that a fluid under strong spatially periodic confinement displays a glass transition within mode-coupling theory at a much lower density than the corresponding bulk system. We use fluctuating hydrodynamics, with confinement imposed through a periodic potential whose wavelength plays an important role in our treatment. To make the calculation tractable we implement a detailed calculation in one dimension. Although we do not expect simple 1d fluids to show a glass transition, our results are indicative of the behavior expected in higher dimensions. In a certain region of parameter space we observe a three-step relaxation reported recently in computer simulations [S. H. Krishnan, Ph.D. thesis, Indian Institute of science (2005); Kim et al., Eur. Phys. J. Special Topics 189, 135 (2010)] and a glass-glass transition. We compare our results to those of Krakoviack [Phys. Rev. E 75, 031503 (2007)] and Lang et al. [Phys. Rev. Lett. 105, 125701 (2010)].
Nanocomposite formation, through the incorporation of high aspect ratio nanoparticles, has been proven to enhance the dielectric properties of thermoplastic polymers, when the mitigation of internal charges and the na...
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A series of new organic semiconducting copolymers composed of {(2E,2′E)-3,3′-[2,5-bis(octyloxy)-1,4-phenylene]-bis[2-(thiophen-2- yl)acrylonitrile]}(OPTAN) and 10(2′-ethylhexylphenothiazine) (PTZ) monomers, (the co...
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作者：
Jianqiang ChenXiaoliang GongHu YangKey Laboratory of Mesoscopic Chemistry of MOE
Department of Polymer Science and Technology School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 P.R.China Physics Department and Shanghai Key Laboratory of Magnetic Resonance East China Normal University Shanghai 200062 P.R.China Key Laboratory of Mesoscopic Chemistry of MOE Department of Polymer Science and Technology School of Chemistry and Chemical Engineering Nanjing U
Advanced materials with excellent piezoresistance sensitivity are attracting more attention due that they can be used as functional materials in pressure sensors. For the researched piezoresistance nanocomposites, we ...
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ISBN:
(纸本)9784886860743
Advanced materials with excellent piezoresistance sensitivity are attracting more attention due that they can be used as functional materials in pressure sensors. For the researched piezoresistance nanocomposites, we employ canbon nanotubes (CNT) with difference aspect ratios as conducting functional fillers and two kinds of polymers (silicone rubber and thermoplastic elastomer) as polymer matrix, which can produce a great strain at low stress so that finally the nancomposites show outstanding piezoresistance sensitivity. Different to the carbon black (CB)/polymer composites, the CNT/polymer nanocomposites display a positive piezoresistance effect (PPRE), namely the resistance of nanocomposites increases with an increase in pressure stress. Therefore, the mechanism of PPRE is studied in this work by employing the insulating SiO_2 nanoparticles and the electrical conducting CB particles as the second kind of fillers. In addition, the effect of aspect ratio (AR) of CNT on piezoresistivity was explored. A correlation between AR of MWNCNT and piezoresistivity of the corresponding composites was established.
Paclitaxel is one of the most effective anticancer drugs for treatment of various human *** introduces a new class ofmicrotubular stabilising drugs, which interfere *** low solubility of paclitaxel in aqueous media, h...
Paclitaxel is one of the most effective anticancer drugs for treatment of various human *** introduces a new class ofmicrotubular stabilising drugs, which interfere *** low solubility of paclitaxel in aqueous media, however, constricts its direct application, and also the unspecific toxicity that not only interferes tumour cell division demands for new concepts of drug ***, improvement of tumour-cell selectivity and enhanced hydrophilicity of paclitaxel remains a goal of high *** review summarises the present knowledge about paclitaxel prodrugs based on macromolecular conjugates and their interaction with constituents of body fluids as well as the potential of tumour-targeted drug delivery by paclitaxel conjugates.
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