Effects of AlGaAs cladding layers on the luminescence of GaAs/GaAs1-xBix/GaAs heterostructures.

The structural and optical properties of GaAs1-xBix quantum wells (QWs) symmetrically clad by GaAs barriers with and without additional confining AlGaAs layers are studied. It is shown that a GaAs/GaAs1-xBix/GaAs QW with x ~ 4% and well width of ~ 4 nm grown by molecular beam epitaxy demonstrates efficient photoluminescence (PL) that becomes significantly more thermally stable when a cladding AlGaAs layer is added to the QW structure. The PL behavior for temperatures between 10 and 300 K and for excitation intensities varying by seven orders of magnitude can be well described in terms of the dynamics of excitons including carrier capture in the QW layer, thermal emission and diffusion into the cladding barriers.

Strong passivation effects on the properties of an InAs surface quantum dot hybrid structure.

We report on an InAs quantum dot (QD) hybrid structure with a top surface QD layer coupled to two buried QD layers that is highly sensitive to surface passivation. After 180 min of passivation, the photoluminescence (PL) peak of the surface QDs shifts from 1545 to 1275 nm while its intensity decreases by one order of magnitude. Time-resolved PL reveals a significant decrease of carrier tunneling between the QD layers because of the surface state modification by chemical treatment.

State filling dependent luminescence in hybrid tunnel coupled dot-well structures.

A strong dependence of quantum dot (QD)-quantum well (QW) tunnel coupling on the energy band alignment is established in hybrid InAs/GaAs-In(x)Ga(1-x)As/GaAs dot-well structures by changing the QW composition to shift the QW energy through the QD wetting layer (WL) energy. Due to this coupling a rapid carrier transfer from the QW to the QD excited states takes place. As a result, the QW photoluminescence (PL) completely quenches at low excitation intensities.

Optical evidence of a quantum well channel in low temperature molecular beam epitaxy grown Ga(AsBi)/GaAs nanostructure.

A Ga(AsBi) quantum well (QW) with Bi content reaching 6% and well width of 11 nm embedded in GaAs is grown by molecular beam epitaxy at low temperature and studied by means of high-resolution x-ray diffraction, photoluminescence (PL), and time-resolved PL. It is shown that for this growth regime, the QW is coherently strained to the substrate with a low dislocation density. The low temperature PL demonstrates a comparatively narrow excitonic linewidth of ∼ 40 meV.

["Structure-anti-arrhythmic activity" relationship of N-phenilacetamide derivatives and amides of aromatic carbonic acids].

Using the computer system SARD-21 (Structure Activity Relationship & Design) structural features of high- and low-effective anti-arrhythmic agents have been recognized and the influence of these features on the anti-arrhythmic properties has been evaluated. This information has been used for generation of the model for prediction of anti-arrhythmic effectiveness of pharmaceutical preparations with the 82%-level of recognition by two methods. The recognized structural parameters may be successfully used for design of new highly effective anti-arrhythmic drugs, and also for modification of structures of known anti-arrhythmic drugs for the increase of effectiveness of their anti-arrhythmic action.