Engineering topics

Gavrilenko, V. I.

Publications and source records attributed to Gavrilenko, V. I..

5 records

DOE OSTI2019

Residual-Photoconductivity Spectra in HgTe/CdHgTe Quantum-Well Heterostructures

Residual-photoconductivity spectra (RPS) are studied for HgTe/CdHgTe quantum-well heterostructures of n- and p-type conduction at T = 4.2 K. RPS is shown to be both positive (an increase in the carrier concentration in the quantum well) and negative depending on the illumination wavelength. The RPS maxima in the sample with n-type conduction in general correspond to the RPS minima in the p-type samples and vice versa. It is found for p-type samples that illumination at specific wavelengths leads to the “freezing” of free carriers in the quantum well (QW) but not to a change in the conduction type. This fact indicates the important role of the built-in electric field in the RPS mechanism; this field is “switched-off” upon QW neutralization.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Balance-equation method for simulating terahertz quantum-cascade lasers using a wave-function basis with reduced dipole moments of tunnel-coupled states

A model based on a system of balance equations for localised and continuum states is developed to calculate the current − voltage (I − V) and power characteristics of quantum-cascade lasers (QCLs) operating in the terahertz (THz) range. A method for modifying the eigenbasis of the Schrödinger equation by reducing the dipole moments of tunnel-coupled states is proposed to take into account the effect of dephasing on the carrier transport. The calculated and experimental data on the current − voltage characteristics and the dependence of the integrated radiation intensity on current for the THz QCLs lasing at 2.3 THz are compared. The calculated and measured values of the threshold current, lasing current range, and maximum operating temperature T{sub max} are found to be in good agreement. It is shown that T{sub max} can be increased by 25 % by reducing the thickness of the top contact layer n{sup +}-GaAs of the laser structure under study from 800 to 100 nm. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2019

Second-Harmonic Generation of Subterahertz Gyrotron Radiation by Frequency Doubling in InP:Fe and Its Application for Magnetospectroscopy of Semiconductor Structures

The possibility of obtaining intense terahertz radiation due to second-order lattice nonlinearity in indium-phosphide crystals doped with iron is discussed. As a source of radiation, subterahertz gyrotrons are considered. It is shown that the efficiency of frequency doubling can reach 3%, which opens up the possibility for developing a new generation of terahertz radiation sources. The possibility of applying second-harmonic radiation for the magnetospectroscopy of semiconductor structures with quasi-Dirac dispersion is demonstrated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Evolution of the Impurity Photoconductivity in CdHgTe Epitaxial Films with Temperature

The photoconductivity spectra of epitaxial CdHgTe films are investigated by Fourier-transform spectroscopy at various temperatures. Features associated with both the interband absorption and ionization of impurity/defect states are found in the spectra. Their evolution with temperature is traced. The temperatures of “vanishing” of the impurity features are determined, which makes it possible to assess the acceptor concentration in the structures under study using the electroneutrality equation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Study of the Auger Recombination Energy Threshold in a Series of Waveguide Heterostructures with HgTe/Cd{sub 0.7}Hg{sub 0.3}Te QWs Near 14 μm

Stimulated emission from a heterostructure with Hg{sub 0.903}Cd{sub 0.097}Te/Cd{sub 0.7}Hg{sub 0.3}Te quantum wells, placed in a waveguide layer of wide-gap CdHgTe, is obtained at wavelengths of 14–11 μm and a temperatures of 18–80 K. The threshold Auger recombination energy is calculated for a set of heterostructures with quantum wells of pure HgTe with a band gap of 90 meV (wavelength 14 μm). The possibility of fabricating lasers operating at 14 μm and working temperatures higher than that of liquid nitrogen is demonstrated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗