Suspended semiconductor nanostructures: physics and technology.

The current state of research on quantum and ballistic electron transport in semiconductor nanostructures with a two-dimensional electron gas separated from the substrate and nanoelectromechanical systems is reviewed. These nanostructures fabricated using the surface nanomachining technique have certain unexpected features in comparison to their non-suspended counterparts, such as additional mechanical degrees of freedom, enhanced electron-electron interaction and weak heat sink. Moreover, their mechanical functionality can be used as an additional tool for studying the electron transport, complementary to the ordinary electrical measurements.

The piezoelectric gating effect in a thin bent membrane with a two-dimensional electron gas.

Thin suspended nanostructures with a two-dimensional electron gas can be used as nanoelectromechanical systems in which electron transport is piezoelectrically coupled to mechanical motion and vibrations. Apart from practical applications, these systems are interesting for studying electron transport under unusual conditions, namely, in the presence of additional mechanical degrees of freedom. In the present paper, we analyze the influence of the bending on the density of a gated two-dimensional electron gas contained in a suspended membrane using the Thomas-Fermi approach and the model of pure electrostatic screening.

Universal behavior of magnetoresistance in quantum dot arrays with different degrees of disorder.

The magnetoresistance in a two-dimensional array of Ge/Si quantum dots was studied in a wide range of zero magnetic field conductances, where the transport regime changes from a hopping to a diffusive one. The behavior of the magnetoresistance is found to be similar for all samples--it is negative in weak fields and becomes positive with increasing magnetic field. The result apparently contradicts existing theories.

[Some features of teenage beer alcoholism combined with hashish addiction].

Sixty male teenagers with beer alcoholism combined with hashish addiction were examined. The beer consumption was promoted by drinking customs existing in the microsociety, curiosity, pressure of other people, the existing opinion on harmlessness of beer and its availability. In all cases, subjects began to use hashish after the development of beer alcoholism.