The stability of a GaAs layer structure consisting of a thin ~10 nm! layer of low-temperature-grown GaAs on a heavily n-doped GaAs layer, both grown by molecular beam epitaxy, has been studied using a scanning tunneling microscope. The sample was exposed to the atmosphere between the layer growth and STM characterization. Tunneling spectroscopy shows both the GaAs band edges and a band of midga...

Scattering of 2D Dirac electrons on a rectangular matrix potential barrier is considered using the formalism of spinor transfer matrices. It is shown, in particular, that in the absence of the mass term, the Klein tunneling is not necessarily suppressed but occurs at oblique incidence. The formalism is applied to studying waveguiding modes of the barrier, which are supported by the edge and bul...

We report on the first experimental observation of photonic Bloch oscillations and Zener tunneling in two-dimensional periodic systems. We study the propagation of an optical beam in a square lattice superimposed on a refractive index ramp. We observe oscillations of the beam inside the first Brilloin zone and tunneling of light from the first to the higher-order bands of the lattice band gap s...

water content plays an important role in the process of plant photosynthesis and biomass accumulation. many methods have been developed to retrieve canopy leaf water content from remote sensing data. however, the validity of these methods has not been verified, which limits their applications. this study estimates the leaf water content (lwc) of winter wheat with three most widely used indexes:...

We experimentally implement the Harper Hamiltonian for neutral particles in optical lattices using laser-assisted tunneling and a potential energy gradient provided by gravity or magnetic field gradients. This Hamiltonian describes the motion of charged particles in strong magnetic fields. Laser-assisted tunneling processes are characterized by studying the expansion of the atoms in the lattice...

Using a first principles electronic structure method, we investigate how a band gap in the surface projected density of states of a noble metal influences the resonant tunneling lifetime of an atomic level near the surface. Comparing Li atoms outside Cu(111), where the Li 2s level is within the gap, with Cu(001), where the Li 2s level is below the gap, reveals that the lifetime of the ionizatio...

We propose a new Metal-oxide-semiconductor carbon-nanotube transistor (MOSCNT) in which source (S) and drain (D) regions are formed by band engineered multi-wall carbon nanotubes (BE-MWCNTs). The gradual potential profiles of these band-engineered S/D regions weakening the longitudinal confinements in the channel reduce the band-to-band tunneling significantly and hence eliminating the ambipola...

In this communication we provide the first UHV-STM images and STM-based current-voltage (I-V) and orbital mediated tunneling spectroscopy (OMTS) data on a self-assembled porphyrin nanostructure at the single structure level. We will show that transverse conductivity over distances less than 10 nm can occur by barrier type tunneling but that long distance conduction solely occurs through the LUM...

The theory of tunnel current-voltage (I-V) characteristics of metal-semiconductor junctions based on the self-consistent solution of Poisson equation allows to get the Schottky-barrier height and the charged impurity concentration directly from the tunnel-ing data. This approach was applied to the analysis of the low temperature experiments on tunneling under pressure up to 3 GPa in a piston-cy...

We investigate single-particle excitation properties in the normal state of a two-band superconductor or superfluid throughout Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein-condensation (BEC) crossover, within many-body T-matrix approximation for multi-channel pairing fluctuations. address density states and spectral functions consisting two contributions associated with waekly interacting d...