We review our recent progress on the fabrication of near-infrared photodetectors based on intersubband transitions in AlN/GaN superlattice structures. Such devices were first demonstrated in 2003, and have since then seen a quite substantial development both in terms of detector responsivity and high speed operation. Nowadays, the most impressive results include characterization up to 3 GHz usi...

We consider an archetypal example of a low-dimensional stochastic web, arising in a 1D oscillator driven by a plane wave of a frequency equal or close to a multiple of the oscillator’s natural frequency. We show that the web can be greatly enlarged by the introduction of a slow, very weak, modulation of the wave angle. Generalizations are discussed. An application to electron transport in a nan...

We study transport through a semiconductor superlattice with an electric field parallel to and a magnetic field perpendicular to the growth axis. Using a semiclassical balance equation model with elastic and inelastic scattering, we find that (1) the current-voltage characteristic becomes multistable in a large magnetic field and (2) "hot" electrons display novel features in their current-volta...

We review stabilization of deterministic chaotic as well as noise-induced spatio-temporal patterns in spatially extended nonlinear systems by time-delayed feedback control. Different control schemes, e.g., a diagonal control matrix, or global control, or combinations of both, are compared. Specifically, we use two models of nonlinear charge transport in semiconductor nanostructures which are of...

We consider noise-induced charge density dynamics in a semiconductor superlattice. The parameters are fixed in the regime below the Hopf bifurcation that gives birth to spatio-temporal oscillations, where in the absence of noise the system rests in a fixed point. It is shown that in this case noise can induce in the superlattice quite coherent oscillations of the current through the device. Whi...

D.G. Walker Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37212, USA Abstract Variably spaced semiconductor superlattice (VSSL) have exhibited superior electron mobility and rectification because of electronic level alignment. We have investigated the thermoelectric properties of VSSL structures using a self-consistent non-equilibrium Green’s function (NEGF) ...

The motion of an electron in a semiconductor superlattice, undergoing the combined action of a static magnetic field perpendicular to its growth direction and intense electromagnetic radiation is considered. Exact numerical solutions of the time-dependent Schrödinger equation are found for a superlattice with a sinusoidal potential. Quasienergies are calculated as function of the cyclotronic or...

We report a theoretical investigation on the band structures of electrons in both infinite and finite semiconductor quantum well/ barrier superlattices with each unit cell containing alternately two types of materials. When the unit cell of a superlattice, made of GaAs and AlxGa1 xAs, is further divided into four and six sublayers of these two materials, narrower passbands and/or broad stopband...

We present the numerical methods and simulations used to solve a charge transport problem in semiconductor physics. The problem is described by a Wigner-Poisson kinetic system we have recently proposed and whose results are in good agreement with known experiments. In this model we consider doped semiconductor superlattices in which electrons are supposed to occupy the lowest miniband, exchange...