1,766,435 research outputs found
1/f noise in graphene
We present a novel and comprehensive model of 1/f noise in nanoscale graphene
devices that accounts for the unusual and so far unexplained experimental
characteristics. We find that the noise power spectral density versus carrier
concentration of single-layer sheet devices has a behavior characterized by a
shape going from the M to the Gamma type as the material inhomogeneity
increases, whereas the shape becomes of V type in bilayer sheet devices for any
inhomogeneity, or of M type at high carrier concentration. In single-layer
nanoribbons, instead, the ratio of noise to resistance versus the latter
quantity is approximately constant, whereas in the bilayer case it exhibits a
linear decrease on a logarithmic scale as resistance increases and its limit
for zero resistance equals the single-layer value. Noise at the Dirac point is
much greater in single-layer than in bilayer devices and it increases with
temperature. The origin of 1/f noise is attributed to the traps in the device
and to their relaxation time dispersion. The coupling of trap charge
fluctuations with the electrode current is computed according to the
electrokinematics theorem, by taking into account their opposite effects on
electrons and holes as well as the device inhomogeneities. The results agree
well with experiments.Comment: 27 pages, 5 figures. The final publication is available at
link.springer.co
1/f noise in nanowires
We have measured the low-frequency resistance fluctuations (1 mHz<f<10 Hz) in
Ag nanowires of diameter 15 nm<d<200 nm at room temperatures. The power
spectral density (PSD) of the fluctuations has a 1/f^{\alpha} character as seen
in metallic films and wires of larger dimension. Additionally, the PSD has a
significant low-frequency component and the value of \alpha increases from the
usual 1 to ~3/2 as the diameter d is reduced. The value of the normalized
fluctuation \frac{}{R^2} also increases as the diameter d is
reduced. We observe that there are new features in the 1/f noise as the size of
the wire is reduced and they become more prominent as the diameter of the wires
approaches 15nm. It is important to investigate the origin of the new behavior
as 1/f noise may become a limiting factor in the use of metal wires of
nanometer dimensions as interconnects.Comment: 9 pages, 6 figures, published in Nanotechnolog
Reducing MOSFET 1/f Noise and Power Consumption by "Switched Biasing"
Switched biasing is proposed as a technique for reducing the 1/f noise in MOSFET's. Conventional techniques, such as chopping or correlated double sampling, reduce the effect of 1/f noise in electronic circuits, whereas the switched biasing technique reduces the 1/f noise itself. Whereas noise reduction techniques generally lead to more power consumption, switched biasing can reduce the power consumption. It exploits an intriguing physical effect: cycling a MOS transistor from strong inversion to accumulation reduces its intrinsic 1/f noise. As the 1/f noise is reduced at its physical roots, high frequency circuits, in which 1/f noise is being upconverted, can also benefit. This is demonstrated by applying switched biasing in a 0.8 ¿m CMOS sawtooth oscillator. By periodically switching off the bias currents, during time intervals that they are not contributing to the circuit operation, a reduction of the 1/f noise induced phase noise by more than 8 dB is achieved, while the power consumption is also reduced by 30
Simple model for 1/f noise
We present a simple stochastic mechanism which generates pulse trains
exhibiting a power law distribution of the pulse intervals and a
power spectrum over several decades at low frequencies with close to
one. The essential ingredient of our model is a fluctuating threshold which
performs a Brownian motion. Whenever an increasing potential hits the
threshold, is reset to the origin and a pulse is emitted. We show that
if increases linearly in time, the pulse intervals can be approximated
by a random walk with multiplicative noise. Our model agrees with recent
experiments in neurobiology and explains the high interpulse interval
variability and the occurrence of noise observed in cortical
neurons and earthquake data.Comment: 4 pages, 4 figure
Temperature square dependence of the low frequency 1/f charge noise in the Josephson junction qubits
To verify the hypothesis about the common origin of the low frequency 1/f
noise and the quantum f noise recently measured in the Josephson charge qubits,
we study temperature dependence of the 1/f noise and decay of coherent
oscillations. T^2 dependence of the 1/f noise is experimentally demonstrated,
which supports the hypothesis. We also show that dephasing in the Josephson
charge qubits off the electrostatic energy degeneracy point is consistently
explained by the same low frequency 1/f noise that is observed in the transport
measurements.Comment: 4 pages, 2 figure
1/f Noise in Electron Glasses
We show that 1/f noise is produced in a 3D electron glass by charge
fluctuations due to electrons hopping between isolated sites and a percolating
network at low temperatures. The low frequency noise spectrum goes as
\omega^{-\alpha} with \alpha slightly larger than 1. This result together with
the temperature dependence of \alpha and the noise amplitude are in good
agreement with the recent experiments. These results hold true both with a
flat, noninteracting density of states and with a density of states that
includes Coulomb interactions. In the latter case, the density of states has a
Coulomb gap that fills in with increasing temperature. For a large Coulomb gap
width, this density of states gives a dc conductivity with a hopping exponent
of approximately 0.75 which has been observed in recent experiments. For a
small Coulomb gap width, the hopping exponent approximately 0.5.Comment: 8 pages, Latex, 6 encapsulated postscript figures, to be published in
Phys. Rev.
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