Results 1 - 10 of 24928
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[en] We discuss the approach of determining the charge-carrier density of a single-carrier device by combining Ohm’s law and the Mott–Gurney law. We show that this approach is seldom valid, due to the fact that whenever Ohm’s law is applicable the Mott–Gurney law is usually not, and vice versa. We do this using a numerical drift-diffusion solver to calculate the current density–voltage curves and the charge-carrier density, with increasing doping concentration. As this doping concentration is increased to very large values, using Ohm’s law becomes a sensible way of measuring the product of mobility and doping density in the sample. However, in the high-doping limit, the current is no longer governed by space-charge and it will no longer be possible to determine the charge-carrier mobility using the Mott–Gurney law. This leaves the value for the mobility as an unknown in the mobility-doping density product in Ohm’s law. We also show that, when the charge-carrier mobility for an intrinsic semiconductor is known in advance, the carrier density is underestimated up to many orders of magnitude if Ohm’s law is used. We finally seek to establish a window of conditions where the two methods can be combined to yield reasonable results. (paper)
[en] Charge carrier mobility is a central transport property in nanoscale electronics. Carbon nanotubes (CNTs) are supposed to have high carrier mobility. The preparation methods of CNTs have been greatly improved, but the defects always exist. This work presented first-principle investigations on the charge carrier mobility of carbon nanotubes containing several intrinsic defects. The charge carrier mobilities of zigzag (10, 0) tubes with Stone–Wales, mono vacant and 5/8/5 defects were studied as an example to explore the role of defects. Most carrier mobilities were decreased, but several values of mobility are unexpectedly increased upon the appearance of the defects. This interesting result is discussed based on the changes of the stretching modulus, the effective mass of the carrier and deformation potential constant induced by the defects. (paper)
[en] InAs monocrystals grown under conditions of varying deviation of the melt composition from the stoichiometry were investigated by hydrostatic weighing, precision measurement of the lattice parameter and measurement of electrophysical properties, viz. concentration, mobility and life of the charge carriers. The nature is established of the inherent structural point defects in the monocrystals at various deviation of the composition from the stoichiometry was shown to affect the concentration, mobility and life of the charge carriers in InAs monocrystals
[en] We investigate the impact of copper on the light induced minority-carrier lifetime degradation in various crystalline silicon materials. We demonstrate here that the presence of neither boron nor oxygen is necessary for the degradation effect. In addition, our experiments reveal that copper contamination alone can cause the light induced minority-carrier lifetime degradation.
[en] An experimental study of RTS (random telegraph signal) noise amplitudes in ultra-thin gate oxide n-MOSFETs biased in sub-threshold and linear regions was conducted. At the same time, a modified model integrating effects of trapped charge and its gate image charge on the carrier number and mobility fluctuations in the conducting channel was presented. Compared with the widely used model, the newly built model fits the experimental RTS noise data of ultra-thin gate oxide n-MOSFETs better than the former one. By employing this model in the extraction of dynamic border trap characteristics by RTS noise means in ultra-thin gate oxide n-MOSFETs, a more accurate result can be expected
[en] Weyl and Dirac Fermions semimetals exhibits exotic transport properties for example high carrier mobility, large positive transverse magnetoresistance, low charge carrier density, low effective mass etc. However, among the very few available tools to characterize Weyl semimetals through electrical transport, negative magnetoresistance is most commonly used. Considering shortcomings of this method, new tools to characterize chiral anomaly in Weyl semimetals are desirable. We employ planar Hall effect as an effective technique in half Heusler Weyl semimetal GdPtBi to study chiral anomaly. This compound exhibits a large value of 1.5 mcm planar Hall resistivity at 2 K and in 9 T. Our analysis reveals that the observed amplitude is dominated by Berry curvature and chiral anomaly contributions. Through the angle dependent transport studies we establish that GdPtBi with relatively small orbital magnetoresistance is an ideal candidate to observe large planar Hall effect.
[en] SiC/C3N4 composites have been prepared by cooling crystallization method in this work for photocatalytic degradation. The sample with appropriate SiC/C3N4 composition(1: 50) exhibited the best performance for photocatalytic oxidation of Rhodamine B, which achieves about 2.5 times efficiency improvement compared with the sample prepared by direct mixing method, and it is also 100 times and 2.3 times than the pristine SiC powder and C3N4 respectively. We attribute the great photocatalytic improvement to the increased BET surface area, enhanced light-absorption ability, longer carriers lifetime and more effective heterostructure in SiC/C3N4 composites prepared by cooling crystallization method. In addition, the photocatalytic degradation mechanism of RhB was discussed in detail, and the accelerated charge-carrier mobility contributes to the improvement as well. (paper)