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The transformation of quantum size levels into virtual levels upon a change in the electric field in an AlAs/GaAs superlattice located in the i region of a p-i-n structure is studied experimentally and theoretically. It is shown that an interfacial state at the boundary between the superlattice and the p-GaAs contact layer results in a resonant increase in the probability of photoelectron tunneling from the contact into the superlattice via Wannier-Stark levels. [ABSTRACT FROM AUTHOR]

Experiments on Raman scattering in the “forward” geometry, permitting observation of anisotropy of the optical phonons, are performed on specially prepared short-period GaAs/AlAs superlattice structures with the substrates removed and the surfaces covered with an antireflective layer. The experimental data agree well with the computational results obtained for the angular dispersion of optical phonons in superlattices on the basis of a modified continuum model. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The nonlocal resistance of a two-dimensional electron gas in a periodic lattice of antidots is investigated. Anomalous growth of this resistance is observed when 2Rc≊d (Rc is the Larmor radius). This growth is caused by the appearance of runaway trajectories, skipping along the antidots and running away along the rows of antidots. It is shown on the basis of a comparative analysis of the local and nonlocal magnetoresistance that the character of the electronic billiard trajectories corresponds to the characteristic features of magnetotransport. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Semiconductor lasers with a vertical cavity with a high external quantum efficiency and high radiation power have been developed and constructed. Powers up to 10 W at T=300 K and 20 W at T= 250 K have been obtained for 500 µm aperture lasers operating in the pulsed regime. [ABSTRACT FROM AUTHOR]

The quantum Hall effect in a single-mode wire is studied for the first time. It is established that a well-expressed quantum Hall resistance for filling factors i = 1 and 2 is observed in magnetic fields in which the magnetic length becomes less than the width of the wire. Breakdown of proportionality with respect to the magnetic field in the arrangement of the Hall quantization plateau and the dissipative conductivity minima is observed. [ABSTRACT FROM AUTHOR]