79,142 research outputs found
The impact of random doping effects on CMOS SRAM cell
The SRAM has a very constrained cell area and is consequently sensitive to the intrinsic parameter fluctuations ubiquitous in decananometer scale MOSFETs. Using a statistical circuit simulation methodology, which can fully collate intrinsic parameter fluctuation information into compact model sets, the impact of random device doping on 6-T SRAM static noise margins, and read and write characteristics are investigated in detail for well-scaled 35 nm physical gate length devices. We conclude that intrinsic parameter fluctuations will become a major limitation to further conventional MOSFET SRAM scaling
Intrinsic Spin Hall Effect in the Two Dimensional Hole Gas
We show that two types of spin-orbit coupling in the 2 dimensional hole gas
(2DHG), with and without inversion symmetry breaking, contribute to the
intrinsic spin Hall effect\cite{murakami2003,sinova2003}. Furthermore, the
vertex correction due to impurity scattering vanishes in both cases, in sharp
contrast to the case of usual Rashba coupling in the electron band. Recently,
the spin Hall effect in a hole doped semiconductor has been observed
experimentally by Wunderlich \emph{et al}\cite{wunderlich2004}. From the fact
that the life time broadening is smaller than the spin splitting, and the fact
impurity vertex corrections vanish in this system, we argue that the observed
spin Hall effect should be in the intrinsic regime.Comment: Minor typos fixed, one reference adde
Two-body hadronic charmed meson decays
We study in this work the two-body hadronic charmed meson decays, including
both the PP and VP modes. The latest experimental data are first analyzed in
the diagrammatic approach. The magnitudes and strong phases of the flavor
amplitudes are extracted from the Cabibbo-favored (CF) decay modes using
minimization. The best-fitted values are then used to predict the
branching fractions of the singly-Cabibbo-suppressed (SCS) and
doubly-Cabibbo-suppressed decay modes in the flavor SU(3) symmetry limit. We
observe significant SU(3) breaking effects in some of SCS channels. In the case
of VP modes, we point out that the and amplitudes cannot be
completely determined based on currently available data. We conjecture that the
quoted experimental results for both and are overestimated. We compare the sizes of color-allowed and
color-suppressed tree amplitudes extracted from the diagrammatical approach
with the effective parameters and defined in the factorization
approach. The ratio is more or less universal among the , and modes. This feature allows
us to discriminate between different solutions of topological amplitudes. For
the long-standing puzzle about the ratio , we argue that, in addition to the SU(3)
breaking effect in the spectator amplitudes, the long-distance resonant
contribution through the nearby resonance can naturally explain why
decays more copiously to than through the
-exchange topology.Comment: 32 pages, 5 figures. An alternative method for error bar extraction
is used; last columns of Tables~I to VI, and all entries in Tables~VII, VIII
and X are modified. To appear in PRD
Matter-wave localization in a random potential
By numerical and variational solution of the Gross-Pitaevskii equation, we
studied the localization of a noninteracting and weakly-interacting
Bose-Einstein condensate (BEC) in a disordered cold atom lattice and a speckle
potential. In the case of a single BEC fragment, the variational analysis
produced good results. For a weakly disordered potential, the localized BECs
are found to have an exponential tail as in weak Anderson localization. We also
investigated the expansion of a noninteracting BEC in these potential. We find
that the BEC will be locked in an appropriate localized state after an initial
expansion and will execute breathing oscillation around a mean shape when a BEC
at equilibrium in a harmonic trap is suddenly released into a disorder
potential
UTB SOI SRAM cell stability under the influence of intrinsic parameter fluctuation
Intrinsic parameter fluctuations steadily increases with CMOS technology scaling. Around the 90nm technology node, such fluctuations will eliminate much of the available noise margin in SRAM based on conventional MOSFETs. Ultra thin body (UTB) SOI MOSFETs are expected to replace conventional MOSFETs for integrated memory applications due to superior electrostatic integrity and better resistant to some of the sources of intrinsic parameter fluctuations. To fully realise the performance benefits of UTB SOI based SRAM cells a statistical circuit simulation methodology which can fully capture intrinsic parameter fluctuation information into the compact model is developed. The impact on 6T SRAM static noise margin characteristics of discrete random dopants in the source/drain regions and body-thickness variations has been investigated for well scaled devices with physical channel length in the range of 10nm to 5nm. A comparison with the behaviour of a 6T SRAM based on a conventional 35nm MOSFET is also presented
Impact of random dopant induced fluctuations on sub-15nm UTB SOI 6T SRAM cells
The CMOS scaling increases the impact of intrinsic parameter fluctuation on the yield and functionality of SRAM. A statistical circuit simulation framework which can fully capture intrinsic parameter fluctuation information into the compact model has been developed. The impact of discrete random dopants in the source and drain regions on 6T SRAM cells has been investigated for well scaled ultra thin body (UTB) SOI MOSFETs with physical channel length in the range of 10nm to 5nm
Influence of chirping the Raman lasers in an atom gravimeter: phase shifts due to the Raman light shift and to the finite speed of light
We present here an analysis of the influence of the frequency dependence of
the Raman laser light shifts on the phase of a Raman-type atom gravimeter.
Frequency chirps are applied to the Raman lasers in order to compensate gravity
and ensure the resonance of the Raman pulses during the interferometer. We show
that the change in the Raman light shift when this chirp is applied only to one
of the two Raman lasers is enough to bias the gravity measurement by a fraction
of Gal (Gal~=~~m/s). We also show that this effect is
not compensated when averaging over the two directions of the Raman wavevector
. This thus constitutes a limit to the rejection efficiency of the
-reversal technique. Our analysis allows us to separate this effect from the
effect of the finite speed of light, which we find in perfect agreement with
expected values. This study highlights the benefit of chirping symmetrically
the two Raman lasers
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