M. P. Telenkov

Intersubband population inversion and induced transitions between the Landau levels in resonance-tunneling multiple quantum-well structures

A new mechanism of creating the population inversion in the system of Landau levels in resonance-tunneling multiple quantum-well structures has been proposed. It has been shown that when the distance between the lower subbands is smaller than the energy of an optical phonon (i.e., when the scattering by optical phonons is suppressed), the population of the ground (zeroth) Landau level of the upper subband can be substantially higher than the population of the first Landau level of the lowest subband, which opens the opportunity of obtaining the tunable-frequency generation of induced terahertz electromagnetic radiation at such a transition.

Intersubband terahertz transitions in Landau level system of cascade GaAs/AlGaAs quantum well structures in strong tilted magnetic field

The tunable terahertz intersubband Landau level transitions in resonant tunneling cascade quantum well structures are considered. The way of lifting the selection rule forbidding the inter-Landau level terahertz transitions of interest by applying a magnetic field tilted with respect to the structure layers is proposed. The importance of asymmetric structure design to achieve considerable values of transition dipole matrix elements is demonstrated.

Spectrum of an electron in a quantum well in high inclined magnetic field and high transverse electric field

The energy and wave functions of localized electron states in a quantum well in a high magnetic field arbitrarily oriented with respect to the layers of the structure, and a high transverse electric field are studied. The situation where the quantum-confined energy and the Landau energy are close to each other is considered. The evolution of the spectrum with varying orientation of the magnetic field over the entire angle range is studied.

Resonant tunneling transport through GaAs/AlGaAs superlattices in strong tilted magnetic field

An analysis is presented of the transverse resonant tunneling transport through GaAs/AlGaAs superlattices due to tunneling between Landau levels in quantum wells in a strong tilted magnetic field. A high tunneling rate is demonstrated between Landau levels with Δn ≠ 0 in a magnetic field with a nonzero in-plane component. This leads to substantial broadening and shift of the tunneling resonance and significant changes in the current-voltage characteristics of superlattices. The predicted behavior of the current-voltage characteristics of superlattices in tilted magnetic fields is demonstrated experimentally.

A microscopic model of sequential resonant tunneling transport through weakly coupled superlattices

A microscopic model is developed for resonant tunneling transport in weakly coupled semiconductor superlattices in a constant external electric field. The model takes into account multiple subbands and electric-field dependence of scattering by acoustic and optical phonons, charged impurities, and interface roughness. The model is used as a basis for computing the resonant-tunneling profiles for structures with small size-quantization energies. The computed results are in good agreement with experiment. In structures of this type, an important role is played by electric-field dependence of scattering processes and the threshold behavior of elastic processes is strongly manifested. A substantial asymmetry is predicted not only for the first tunneling resonance, but also for higher order resonant tunneling processes.

Resonant-tunneling structure of quantum wells in the p-i-n photovoltaic element

The method for efficient separation of photoexcited carriers, based on the resonant tunneling phenomenon in the quantum well structure placed into the i-region of the p-i-n photovoltaic element, is proposed. The parameters of quantum well structures based on the GaAs/Ga1−xInxAs system, implementing the mode of sequential resonant tunneling in the electric field of the GaAs p-i-n junction, is calculated. A microscopic model of resonant-tunneling transport in such structures is constructed, and the kinetic tunneling times are calculated depending on well and barrier parameters. The possibility of achieving sufficiently short (<∼10 ps) tunneling times and, hence, quite efficient removal of photoelectrons and photoholes from quantum wells at a proper choice of barrier powers is shown.

GaAs(1-x)Bix: A Promising Material for Optoelectronics Applications

ABSTRACT Bismuth alloying with GaAs has promised greater advantages in the realization of more convenient mid and near IR photonic devices owing to its novel and unique properties. The coexistence of faster band gap reduction and a strong increase in spin-orbit splitting energy with an increase in Bi concentration is one of those. However, the realization of practical devices is hindered due to several critical issues associated with the electronic properties of this material. Many of these limitations primarily arise due the difficulty obtaining high-quality structures. In this article, we review the growth and properties of GaAs(1−x)Bix. We have provided a comprehensive study of the properties by considering both from a fundamental perspective and also on their potential device applications.

Mechanism of energy relaxation in the system of Landau levels in quantum wells

The kinetics of intersubband relaxation of electron energy has been studied in the system of Landau levels lying below the optical phonon energy. The relaxation character in the considered system is revealed to differ qualitatively from that in the two-dimensional continuous subband of the quantum well. In particular, the mechanisms of electron subsystem thermalization and energy relaxation in the system of Landau levels are qualitatively different, and the electron subsystem relaxation time exceeds the thermalization time by several orders of magnitude.

Carrier dynamics and stimulated radiative terahertz transitions between Landau levels in cascade GaAs/AlGaAs quantum well structures

The carrier distribution over Landau levels was studied in resonant tunneling GaAs/AlGaAs quantum well structures under tunneling pumping of the upper subband. The numerical calculations of the Landau level populations for various values of pumping intensity (tunneling time), magnetic field and structure doping were carried out. The population inversion between zeroth Landau level of the upper subband and the first Landau level of the lowest subband was shown to exist in wide range of the magnetic field strength. The effect of various scattering mechanisms, both two-particle (electron-electron scattering) and single-particle (acoustic phonon and interface roughness scattering) ones, on level population was studied. The way of lifting the selection rule forbidding the inter-Landau level terahertz transitions of interest and achieving considerable values of the dipole matrix element is proposed.

Resonant tunneling GaAs/AlGaAs quantum well structures for p-i-n photovoltaic cells

This study is devoted to the development of resonant-tunneling structures of quantum wells implementing resonant matching of lower subbands of size quantization in an electric field of the p-i-n junction of photovoltaic elements. The method for controlling the lower subband position in quantum wells by introducing a series of the tunnel-transparent barriers into a quantum well is proposed. The possibility of varying the level position in deep quantum wells in a wide range up to the continuous spectrum is demonstrated on a grown model structure; in this case, agreement between calculated and experimental subband positions is achieved.