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Power Dependence (power + dependence)
Selected AbstractsSolution-Processable Near-IR Photodetectors Based on Electron Transfer from PbS Nanocrystals to Fullerene DerivativesADVANCED MATERIALS, Issue 6 2009Krisztina Szendrei Nanocrystal/fullerene derivative inorganic,organic hybrid photodetectors exhibiting high detectivity for near-IR wavelengths and a linear power dependence are produced. The ultrafast electron transfer from the PbS crystals to the fullerene opens a new route to obtaining efficient photodetectors that are appealing, cost-effective alternatives to the currently available technology. [source] Upconversion Luminescence in ,-AlON:Yb3+,Tm3+ Ceramic PhosphorsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Fang Zhang Upconversion emission properties of ,-AlON:Yb3+,Tm3+ phosphors were investigated under single-wavelength diode laser excitation of 980 nm. Blue (479 nm) and red (653 nm) emission bands were observed which correspond to the transitions of 1G4,3H6 and 1G4,3F4 of Tm3+ ions, respectively. The upconversion spectra show a concentration-dependent luminescence intensity, reaching its peak at a concentration of 1.2 mol% Yb and 0.5 mol% Tm. Pump power dependence of the upconversion emission intensity (P,I) revealed that a two-photon process was involved in the blue and red emissions. [source] Electrical Properties of Cerium-Doped BaTiO3JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2001Jin Hyun Hwang The high-temperature equilibrium electrical conductivity of Ce-doped BaTiO3 was studied in terms of oxygen partial pressure, P(O2), and composition. In (Ba1,xCex)TiO3, the conductivity follows the ,1/4 power dependence of P(O2) at high oxygen activities, which supports the view that metal vacancies are created for the compensation of Ce donors, and is nearly independent of P(O2) where electron compensation prevails at low P(O2). When Ce is substituted for the normal Ti sites, there is no significant change in conductivity behavior compared with undoped BaTiO3, indicating the substitution of Ce as Ce4+ for Ti4+ in Ba(Ti1,yCey)O3. The Curie temperature (Tc) was systematically lowered when Ce3+ was incorporated into Ba2+ sites, whereas the substitution of Ce4+ for Ti4+ sites resulted in no change in this parameter. [source] Molecular Dynamics Simulations of Polymer Translocations,MACROMOLECULAR THEORY AND SIMULATIONS, Issue 5 2004Richard Randel Abstract Summary: Molecular dynamics simulation studies of the translocation of charged homopolymers of length, N, driven by an electric potential gradient through a channel have been performed. We find that the translocation time, ,, displays an inverse power dependence on the temperature of the simulation ,,,,(T,,,T0),7/4, which is in very good agreement with experimental results. In addition, the dependence of , on the driving field strength and the velocity of translocation on the polymer length N have also been obtained. The results suggest that such minimalist models are useful in modelling biological processes and that the molecular dynamics method is a suitable approach for carrying out these simulations. Snapshot of the polymer during the simulation. [source] Analysis of minority carrier lifetime for InAlAs/InGaAs high electron mobility transistors by using 1.55-,m femto-second pulse laserPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008Hirohisa Taguchi Abstract The minority carrier lifetime (,) of High electron mobility transistors (HEMTs) made using the InAlAs/InGaAs material system lattice-matched to the InP substrate had been obtained from optical response measurements with a 1.55-,m femto-second pulse laser where the laser was illuminated onto the backside of a wafer. The drain current of HEMTs associated with the optical pulse was detected using a digitizing oscilloscope, and , was estimated from the exponential dependence of drain current on time. In our current investigation, we found that , is dominated by the following modes: (1) the amount of time required for holes to transit across the channel toward the source, and (2) the amount of time required for the holes accumulated in the source region to recombine with two-dimensional electron gas (2DEG) through the Auger mechanism. Because the sheet concentration (ps) of holes accumulated in source region is low at a low source-to-drain voltage (VDS), Auger recombination is not predominant, and , was only dominated by the hole transit time. At a high VDS, ps became high enough for Auger recombination to occur and dominate ,. Furthermore, we investigated the optical power dependence of , where the optical power was supplied in a continuous wave (CW) to generate photo-excited holes in a steady state. The value of , decreased monotonically as VDS increased and saturated in as little as 6x10,10 s when the optical power was increased. The theoretical investigation was made to understand this saturation phenomenon. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Single photon correlation measurements in a study of excitation process of individual CdTe/ZnTe quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006J. Suffczy Abstract We present the results of systematic autocorrelation and cross-correlation measurements performed on photons originating from various excitonic transitions in a single CdTe/ZnTe quantum dot (QD). Excitation power dependence of photoluminescence intensity was also measured on the same dot under the same experimental conditions. Recorded correlation histograms have provided evidence for memory effects in QD photoluminescence extending over a few excitation periods. Rate equation model assuming a ladder of states and excitation through a single carrier and exciton capture, is fitted to the data. As a consequence, simultaneous quantitative description of the results of both, correlation and power dependence, is obtained. Strong evidence is presented for a QD excitation by capture of single carriers rather than entire excitons. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Reactive ion etching of dielectrics and silicon for photovoltaic applicationsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2006Prakash N. K. Deenapanray Abstract This paper investigates the reactive ion etching of SiO2, Si3N4, and Si using CHF3/O2 plasma. In particular, we have characterized the time and rf power dependence of the carrier lifetimes in n- and p-type FZ Si. The time dependence of reactive ion etching (RIE) at different rf powers provide insight into the two competing processes of damage accumulation and damage removal in the near-surface region of the Si during plasma etching. The carrier lifetime, measured using the quasi-steady-state photoconductance (QSSPC) technique, has a quadratic dependence on the rf power, which can be related to changes in the dc self-bias generated by the plasma at different rf powers. The change in carrier lifetime is similar in both n- and p-type Si of the same doping concentration. Using this fact, together with the electronic properties of defects obtained by deep level transient spectroscopy (DLTS), we have modeled the injection-dependence of the measured carrier lifetimes using the Shockley,Read,Hall model. The isochronal annealing behavior of plasma etched Si has also been studied. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||