34 research outputs found
Experimental Study of Pressure Influence on Tunnel Transport into 2DEG
We present the concept and the results of pilot measurements of tunneling in
a system {Al/-GaAs} under pressure up to 2 GPa at 4.2 K. The
obtained results may indicate the following: the barrier height for
{Al/-GaAs} equals to 0.86 eV at P=0 and its pressure coefficient is ; charged impurity density in the delta-layer starts to drop from
down to at about 1.5
GPa; metal-insulator transition may occur in 2DEG at about 2 GPa
Near-Zone Field Effect of FIR Laser Radiation on Tunnel Current through the Schottky Barrier under Plasma Reflection Condition
Self-consistent solution of Kohn-Sham equations for infinitely extended systems with inhomogeneous electron gas
The density functional approach in the Kohn-Sham approximation is widely used
to study properties of many-electron systems. Due to the nonlinearity of the
Kohn-Sham equations, the general self-consistence searching method involves
iterations with alternate solving of the Poisson and Schr\"{o}dinger equations.
One of problems of such an approach is that the charge distribution renewed by
means of the Schr\"{o}dinger equation solution does not conform to boundary
conditions of Poisson equation for Coulomb potential. The resulting instability
or even divergence of iterations manifests itself most appreciably in the case
of infinitely extended systems. The published attempts to deal with this
problem are reduced in fact to abandoning the original iterative method and
replacing it with some approximate calculation scheme, which is usually
semi-empirical and does not permit to evaluate the extent of deviation from the
exact solution. In this work, we realize the iterative scheme of solving the
Kohn-Sham equations for extended systems with inhomogeneous electron gas, which
is based on eliminating the long-range character of Coulomb interaction as the
cause of tight coupling between charge distribution and boundary conditions.
The suggested algorithm is employed to calculate energy spectrum,
self-consistent potential, and electrostatic capacitance of the semi-infinite
degenerate electron gas bounded by infinitely high barrier, as well as the work
function and surface energy of simple metals in the jellium model. The
difference between self-consistent Hartree solutions and those taking into
account the exchange-correlation interaction is analyzed. The case study of the
metal-semiconductor tunnel contact shows this method being applied to an
infinitely extended system where the steady-state current can flow.Comment: 38 pages, 9 figures, to be published in ZhETF (J. Exp. Theor. Phys.
Reflection of electrons during tunneling and an intersubband polaron in the 2D electron system of a delta-layer in GaAs
Experimental testing and design model for bent FRP anchors exhibiting fiber rupture failure mode
The implementation of Fiber Reinforced Polymer (FRP) anchors in Externally Bonded Fiber Reinforced Polymer (EBR-FRP) systems is an effective method to increase the bond strength and/or ensure the continuity of the load path between FRP materials and the concrete substrate when EBR-FRP systems are used to strengthen and/or repair existing structures. Multiple design examples of EBR-FRP systems exist in the literature, and design guidelines have been compiled in several countries. However, currently these design guidelines do not specifically include guidance on the design of FRP anchors. This lack of design guidance is one of the main impediments to widespread implementation of FRP anchors in the civil engineering industry. The present study reports an experimental program consisting of 32 bent FRP anchor specimens of different sizes and widths that was undertaken to characterize the behavior of bent FRP anchors when the fiber rupture failure mode is exhibited. A design methodology for the mean value and for the lower bound characteristic values (95 and 99.87 percentile equations) is proposed and the reliability of the methodology is assessed.Enrique del Rey Castillo, Dmytro Dizhur, Michael Griffith, Jason Ingha