V. N. Murzin

Current hysteresis collapse and the formation condition for electric-field domains in lightly doped superlattices

It is shown that under resonance tunneling conditions the energy structure of electric-field domains in doped superlattices is substantially different from a resonance structure. As the impurity concentration decreases, the domain walls become wider and the current hysteresis becomes narrower (collapses) as a result of the mismatch of the resonance levels in the region of a domain wall. A physical interpretation of the criterion for the existence of electric-field domains is given.

Dynamic characteristics of “low-temperature” gallium arsenide for terahertz-range generators and detectors

The lifetime of free photoexcited carriers in epitaxial films of “low-temperature” gallium arsenide (LT-GaAs) is determined by the pump-probe optical reflection method. The dark resistivity of LT-GaAs layers is estimated. Emission spectra of LT-GaAs photoconductive antennas are measured in the terahertz frequency region by the Fourier transform spectroscopy.

Energy filtration effect and the possibility of the generation of terahertz radiation in resonant tunneling structures with several quantum wells

The properties of a high-frequency response in resonant tunneling double-well nanostructures have been considered for various energies of electrons arriving to a structure of electrons, various frequencies of the external electromagnetic field, and various features associated with the interaction of electronic states in neighboring quantum wells in double-well nanostructures. The energy filtration effect that is caused by the breaking of the symmetry of the high-frequency response in double-well nanostructures in a static electric field has been revealed. This effect leads to a sharp increase in the gain under conditions of the quantum amplification regime and opens real prospects of a significant increase in the efficiency of solid amplifying and generating devices based on resonant tunneling double-well nanostructure in the subterahertz and terahertz frequency ranges.

Comprehensive study of structural and optical properties of LT-GaAs epitaxial structures

The results of the comprehensive study of LT-GaAs epitaxial structures on GaAs and Si substrates by high-energy electron diffraction, reflection anisotropy spectroscopy, atomic force microscopy, X-ray diffraction, Raman scattering, and photoluminescence methods are presented. The results obtained indicate the existence of several channels of nonequilibrium carrier recombination, which depend, in particular, on the substrate type and on the complex dependence of the concentration of structural imperfections on the used technology and growth conditions of the structures.

Josephson Fourier spectrometer based on HTSC: Construction and the problem of physical implementation of a quantum computer

The possibility of developing the broadband Fourier spectrometer based on the unsteady Josephson effect in HTSC, with a frequency range including the terahertz region, is considered. A simple design of a precisely tuned point Josephson junction is developed, which allows “fitting” of its parameters immediately under cryogenic conditions. A modification of such a spectrometer for solving the problems of factorizing multidigit numbers is proposed, which is currently one of the best known motivations of works on the quantum computer development.

Single-well resonant-tunneling diode heterostructures based on In0.53Ga0.47As/AlAs/InP with the peak-to-valley current ratio of 22:1 at room temperature

Current-voltage (I–V) characteristics of resonant-tunneling diode In0.53Ga0.47As/AlAs/InP structures are studied at 300 and 77 K. The peak-to-valley current ratios were determined as 22:1 and 44:1 at temperatures of 300 and 77 K, respectively, which correspond to the maximum values for InGaAs/AlAs/InP heterostructures without an additional InAs layer of a quantum subwell in their configuration.

Nonlinear quantum mode of terahertz electromagnetic wave amplification in resonant tunneling heterostructures

An analysis of high-frequency properties of the resonant tunneling diode (RTD) in a strong microwave electromagnetic field showed that the high-frequency current response increasing with the microwave power significantly more rapidly saturates out in the case of classical amplification mode, than in the case of “quantum” amplification mode. This makes the “quantum” mode even more attractive in comparison with the classical mode from the viewpoint of the possibility of amplification and generation in the range of subterahertz and terahertz frequencies and offers new opportunities to advance towards these frequencies.

Photoluminescence characterization technique for resonant-tunneling structures based on a long-period GaAs/AlGaAs superlattice, applicable at different stages of fabrication

A technique is developed for the photoluminescence-spectroscopy characterization of resonant-tunneling structures based on a long-period GaAs/AlGaAs superlattice that can be used for quality evaluation at all the stages of fabrication, including molecular-beam epitaxy, photolithography, and annealing. Factors such as the small energy difference between the quantum confined states in wide quantum wells, which make the photoluminescence characterization of such structures more difficult are taken into account. The long-period multiquantum-well structures are promising for the development of a new kind of solid-state intersub-band-transition devices emitting the narrow band radiation in far infrared. Their potential is essentially based on the fact that the scattering and the decay of carriers in the lower quantum-confined states may or may not involve optical phonons. The technique works at both liquid-helium and room temperature. It helps one optimize the process conditions to fabricate high-quality wide-quantum-well structures with excellent uniformity and desired parameters.

Transformation kinetics of electric field domains in weakly coupled GaAs/AlGaAs superlattices in a transverse electric field

Transformation kinetics of the resonant-tunneling domain structure in a superlattice in a rapidly varying electric field is investigated using real-time studies of current response. It is shown that the kinetics is mainly determined by a lag in redistribution of the space charge that forms the domain boundary. A nonmonotonic oscillatory dependence of the transient-process duration on the amplitude of a voltage pulse is observed, as well as the effect of the weak dependence of the transformation time on the displacement of the domain boundary, which indicates that the transformation processes is discrete. Possibilities for controlling the switching processes in a multistable system of current states in weakly coupled semiconductor superlattices are discussed.

Optical intersubband transitions in strained quantum wells utilizing In1−xGaxAs/InP solid solutions

Infrared absorption in strained p-type In1−xGaxAs/InP quantum wells is investigated for both possible types of strain (tensile and compressive). It is observed that the normalincidence absorption increases considerably under compressive strain (when the ground state is a heavy-hole state) and decreases under tensile strain (when the ground state is a light-hole state). The peak absorption in the compressed quantum well can attain very large values, on the order of 5000 cm−1 at a hole density ∼ 1012 cm−2; this attribute makes “compressed” p-type quantum wells attractive for IR detection applications.