Showing papers on "Finite potential well published in 1988"
TL;DR: The present effect exhibits the non-locality, free of topological considerations, although it is related to the Berry phase, another much-discussed recent phenomenon as discussed by the authors. But because of the topological aspects to that effect, which are quite fascinating in their own right, there is an unfortunate tendency to connect these two independent elements.
Abstract: The Aharonov-Bohm effect effords a beautiful insight into the non-local nature of quantum theory. Unfortunately, because of the topological aspects to that effect, which are quite fascinating in their own right, there is an unfortunate tendency to connect these two independent elements. The present effect exhibits the non-locality, free of topological considerations, although it is related to the Berry phase, another much-discussed recent phenomenon. The effect consists of keeping a particle confined to a small region of a box with infinite walls. If the wall of the box is moved, then even though the particle is nowhere near the wall, it will experience a phase shift, which in principle is subject to experimental verification.
56 citations
TL;DR: In this article, the authors presented the quantum efficiency and detectivity of an infrared detector based on photoemission from a quantum well and estimated the dark current and found that, for a GaAs quantum-well detector designed for 10μm operation, the optimal electron density was 2×1011 cm−2 at 77 K.
Abstract: Calculations of the quantum efficiency and detectivity of an infrared detector based on photoemission from a quantum well are presented. The detector is most efficient when a resonant‐extended state exists near the top of the well. The quantum efficiency also increases with increasing electron density. However, due to screening, the absorption peaks at a higher energy than the difference of the energies of the resonant‐extended and the bound states by an amount which is proportional to the carrier density in the well. This causes the detectivity (D*) to have a maximum with respect to electron density. We have estimated the dark current and found that, for a GaAs quantum‐well detector designed for 10‐μm operation, the optimal electron density was 2×1011 cm−2 at 77 K. We have also performed calculations for a quantum‐well detector for which the light coupling has been enhanced by incorporating a diffraction grating into the detector. For the stated electron density, we find a D* of 2.8×1011 cm Hz1/2/W and a...
35 citations
TL;DR: In this paper, the Stokes-Einstein equation is used to model the diffusion of adhesive hard spheres in a marginal solvent like benzene, where sterically stabilized silica particles exhibit an effective attraction due to the interaction of solvent molecules with stabilizing chains.
Abstract: When dispersed in a marginal solvent like benzene, sterically stabilized silica particles exhibit an effective attraction. This attraction is due to the interaction of solvent molecules with the stabilizing chains and is modeled by a square‐well potential; the well has a depth of e/kT=L(θ/T−1), σ≤r≤σ+Δ. L is an interaction parameter, θ the theta temperature of the chain–solvent pair, σ the particle diameter and Δ the width of the square well. An expression for the diffusivity of adhesive hard spheres is derived with the help of the general Stokes–Einstein equation. The model allows scaling to one master plot of experimentally determined diffusion coefficients for samples of six volume fractions, at 20 different temperatures and for each sample at three scattering angles. Additional results obtained with the model are discussed as well. Phase separation in the abovementioned silica dispersions occurs at a well depth of about 5 kT.
30 citations
TL;DR: In this paper, the Schrodinger equation was solved for the truncated Gaussian potential barrier using a power series solution and a general expression was obtained for the transmission coefficient, which indicated that it is the unrealistic discontinuities in potential models that cause such oscillatory behavior.
Abstract: The Schrodinger equation is solved for the truncated Gaussian potential barrier using a power series solution and a general expression is obtained for the transmission coefficient. For this potential barrier, computer calculations show only a trace of the oscillatory behavior that characterizes the penetration of a rectangular barrier. The oscillations diminish rapidly as the discontinuity in the potential function approaches zero. The results indicate that it is the unrealistic discontinuities in potential models that cause such oscillatory behavior.
20 citations
TL;DR: In this article, the diffusion coefficient and velocity autocorrelation function for a fluid of particles interacting through a square-well or square-shoulder potential are calculated from a kinetic theory similar to the Davis-Rice-Sengers theory and the results are compared to those of computer simulations.
Abstract: The diffusion coefficient and velocity autocorrelation function for a fluid of particles interacting through a square-well or square-shoulder potential are calculated from a kinetic theory similar to the Davis-Rice-Sengers theory and the results are compared to those of computer simulations. At low densities the theory yields too low estimates due to the neglect of correlations between subsequent partial collisions of identical pairs; in particular, the neglect of boundstate effects appears important. At intermediate densities the theory makes reasonable predictions and at high densities it produces too high values, due to the neglect of ring terms and other correlated collision events. The results for the square-shoulder potential generally exhibit better agreement between theory and simulations than do those for the square-well potential.
10 citations
TL;DR: The integral eigenvalue equation of the Hamiltonian with a finite-range potential is transformed so as to explicitly take into account the particular structure of a potential consisting of a finite collection of nonoverlapping, muffin-tin\char21{}type individual potentials (scatterers).
Abstract: The integral eigenvalue equation of the Hamiltonian with a finite-range potential is transformed so as to explicitly take into account the particular structure of a potential consisting of a finite collection of nonoverlapping, muffin-tin\char21{}type individual potentials (scatterers). The separation between structure and potential, thought to be obtained as an exact result in the framework of multiple-scattering theory, is found to represent an approximation which originates in having considered what is only a necessary condition to be both necessary and sufficient. As an application, the equation for the energy levels of a muffin-tin periodic potential is discussed and shown to be represented by the Korringa-Kohn-Rostoker equation only as an approximate result.
4 citations
TL;DR: In this article, a semiconductor heterochannel is shown to behave like a two-dimensional electron gas when the channel width d is sufficiently small and, with increasing d, three-dimensional features develop.
Abstract: A semiconductor heterochannel is both a dielectric sandwich structure and a quantum‐well structure. When the channel width d is sufficiently small, charge carriers in it behave like a two‐dimensional electron gas. With increasing d, three‐dimensional features develop. As this takes place, there is an interesting and somewhat counterintuitive interplay in determining the total interaction energy of the system, between the spreading of the wavefunctions in the third direction and the ‘‘channeling’’ of electric field lines.
3 citations
TL;DR: In this paper, a statistical potential function, which is phonon-like in the low frequency limit, is introduced and the effects on barrier penetration and eigenenergies are studied.
Abstract: The Feynman path integral formulation of quantum mechanics has been applied to the calculation of the equilibrium probability density functions for carriers in confining structures. Specifically, in this paper, we present results for a finite square well (single quantum well) and a double barrier (resonant tunneling) structure. A statistical potential function, which is phonon-like in the low frequency limit, is introduced and the effects on barrier penetration and eigenenergies are studied. Both the barrier penetration and eigenenergies are found to be reduced. Though the techniques used are capable of producing quantitative information, emphasis here is placed on the qualitative effects of a statistical potential. We believe these results demonstrate the applicability of the path integral formalism to the study of ultra-small devices.
2 citations