scholarly journals Numerical Studies of Miniband Conduction in Quasi-One-Dimensional Superlattices

VLSI Design ◽  
2001 ◽  
Vol 13 (1-4) ◽  
pp. 45-50 ◽  
Author(s):  
N. Mori ◽  
C. Hamaguchi ◽  
L. Eaves ◽  
P. C. Main
Keyword(s):  
Quantum Limit ◽  
Main Peak ◽  
Restricted Range ◽  
Marked Contrast ◽  
Strong Suppression ◽  
One Dimensional ◽  
Conduction Electrons ◽  
Numerical Studies ◽  
Cyclotron Energy ◽  
Lower Electric Field

Monte Carlo simulations of electron motion in GaAs/A1As superlattices with narrow mini-band width are performed to investigate the effect of a strong magnetic field on miniband conduction. In the quantum limit at low temperatures when the cyclotron energy exceeds the miniband width, the miniband conduction is found to exhibit a strong suppression. This results from the quasi-one-dimensional states formed in the quantum limit and the restricted range of the scattering processes available to the conduction electrons. A small shoulder on the lower electric field side of the main peak is also found in marked contrast with Esaki-Tsu and Ignatov models.

One-dimensional electron channels in the quantum limit

1994 ◽  
Vol 49 (19) ◽  
pp. 14074-14077 ◽  
Author(s):  
H. Drexler ◽  
W. Hansen ◽  
S. Manus ◽  
J. P. Kotthaus ◽  
M. Holland ◽  
...  
Keyword(s):  
Quantum Limit ◽  
Dimensional Electron ◽  
One Dimensional

SMALL-TO-LARGE POLARON CROSSOVER IN ONE DIMENSION USING VARIATIONAL PHONON-AVERAGING TECHNIQUES

2001 ◽  
Vol 15 (13) ◽  
pp. 1923-1937 ◽  
Author(s):  
P. CHOUDHURY ◽  
A. N. DAS
Keyword(s):  
One Dimension ◽  
Density Matrix Renormalization Group ◽  
Phonon Coupling ◽  
One Dimensional ◽  
Variational Techniques ◽  
Density Matrix Renormalization ◽  
Numerical Studies ◽  
Real Picture ◽  
Analytical Approaches ◽  
Averaging Techniques

The ground-state properties of polarons in a one-dimensional chain is studied analytically within the modified Lang–Firsov (MLF) transformation using various phonon-averaging techniques. The object of the work is to examine how the analytical approaches may be improved to give rise to the real picture of polaronic properties as predicted by extensive numerical studies. The results are compared with those obtained from numerical analyses using the density matrix renormalization group (DMRG) and other variational techniques. It is observed that our results agree well with the numerical results particularly in the low and intermediate range of phonon coupling.

Experimental investigation on the secondary instability of liquid-fluidized beds and the formation of bubbles

2002 ◽  
Vol 470 ◽  
pp. 359-382 ◽  
Author(s):  
PAUL DURU ◽  
ÉLISABETH GUAZZELLI
Keyword(s):  
Fluidized Beds ◽  
Secondary Instability ◽  
Analytical Models ◽  
Physical Origin ◽  
Weakly Nonlinear ◽  
One Dimensional ◽  
Numerical Studies ◽  
Wavy Structure ◽  
Nonlinear Simulations ◽  
The One

The objective of the present work is to investigate experimentally the secondary instability of the one-dimensional voidage waves occurring in two-dimensional liquid- fluidized beds and to examine the physical origin of bubbles, i.e. regions devoid of particles, which arise in fluidization. In the case of moderate-density glass particles, we observe the formation of transient buoyant blobs clearly resulting from the destabilization of the one-dimensional wavy structure. With metallic beads of the same size but larger density, the same destabilization occurs but it leads to the formation of real bubbles. Comparison with previous analytical and numerical studies is attempted. Whereas the linear and weakly nonlinear analytical models are not appropriate, the direct nonlinear simulations provide a qualitative agreement with the observed destabilization mechanism.

scholarly journals CLASSICAL TO QUANTUM CROSSOVER IN HIGH-CURRENT NOISE OF ONE-DIMENSIONAL BALLISTIC WIRES

2001 ◽  
Vol 01 (04) ◽  
pp. C21-C33 ◽  
Author(s):  
FREDERICK GREEN ◽  
MUKUNDA P. DAS
Keyword(s):  
Kinetic Theory ◽  
Energy Loss ◽  
Experimental Techniques ◽  
Current Noise ◽  
Current Fluctuations ◽  
High Current ◽  
Strong Suppression ◽  
One Dimensional ◽  
Explicit Dynamics ◽  
Inelastic Energy Loss

Microscopic current fluctuations and conductance are inseparable. We present a unified kinetic theory of both quantized conductance and nonequilibrium noise in one-dimensional ballistic wires. We show that high-current ballistic fluctuations depend, directly and robustly, on carrier statistics. This is dramatically evident in the large noise peaks predicted to coincide with the quantized steps in the two-probe conductance. The outstanding features of nonlinear ballistic fluctuations are: (i) their observability by standard experimental techniques; (ii) their strong suppression by electron degenercy; (iii) their divergence in any model that ignores the explicit dynamics of dissipative scattering in the macroscopic leads; (iv) their numerical dominance over the noise predictions of the Landauer-Büttiker model. The nonequilibrium noise of hot ballistic carriers is strikingly sensitive to their inelastic energy loss on entering the leads. Uniquely and quantitatively, it characterizes the observed nonideality of quantized conductance.

Synthesis and Photoluminescence of Amorphous Ca5Ge2O9 Nanowires

2008 ◽  
Vol 8 (12) ◽  
pp. 6376-6380 ◽  
Author(s):  
Meng-Yen Tsai ◽  
Chung-Yi Yu ◽  
Tsong-Pyng Perng
Keyword(s):  
Inductively Coupled Plasma ◽  
Vapor Condensation ◽  
Mass Spectrometric ◽  
Main Peak ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Inductively Coupled ◽  
Violet Luminescence ◽  
New Thinking

A new method to prepare amorphous Ca5Ge2O9 nanowires is demonstrated in the present study. Germanium nanoparticles with the size ranging from 10 to 50 nm were first prepared by a vapor condensation technique. Upon immersing the nanoparticles in Ca(OH)2 aqueous solution, hydrated Ca5Ge2O9 nanowires were formed rapidly. The phase was determined by X-ray diffraction, and the stoichiometry of Ca:Ge was further confirmed by energy-dispersive X-ray spectroscopic and inductively coupled plasma-mass spectrometric analyses. The diameter of nanowires varied from several tens to more than 100 nm, and the length increased with aging time up to the completion of reaction. After dehydrating at 400 °C, the nanowires became amorphous, and the stoichiometry of Ca:Ge remained unchanged. A blue-violet luminescence was detected from these amorphous nanowires. The emission band distributed from 300 to 550 nm, with the main peak locating at 380 nm. Ge-associated luminescence centers are proposed to be responsible for this emission. The formation of amorphous Ca5Ge2O9 nanowires may provide a new thinking to prepare other kinds of amorphous one-dimensional nanomaterials.

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