Index of content:
Volume 34, Issue 1, January 2008
- LOW-DIMENSIONAL AND DISORDERED SYSTEMS
34(2008); http://dx.doi.org/10.1063/1.2832363View Description Hide Description
A high and narrow peak of the interlayer differential tunneling conductance was found recently in experiments on double-layer electron systems in the quantum Hall effect regime at a total filling of the Landau levels. This peak is a consequence of phase coherence that is established in the system owing to the Bose condensation of electron-hole pairs with components belonging to different layers. The influence of a parallel magnetic field on the tunneling conductance of double-layer systems of small size is considered. It is shown that at finite temperatures the magnetic-field dependence of the height of the peak of the tunneling conductance has a form that resembles a Fraunhofer diffraction pattern.
Quantum and surface states of charge carriers in the optical spectra of nanoclusters in a low-permittivity matrix34(2008); http://dx.doi.org/10.1063/1.2832356View Description Hide Description
The optical spectra of quantum dots of and grown in borosilicate glass by the sol–gel method are obtained and analyzed. It is found that at concentrations of the two semiconductors the emission spectra are due to annihilation of free (internal) excitons in quantum states. The mean size of the quantum dots(QDs) for a given concentration of and is calculated and found to be in good agreement with the x-ray data, and the exciton binding energy is calculated with allowance for the dielectric mismatch between the semiconductor and matrix. It is proposed that this mismatch may be the cause giving rise to the excitonpercolation level that is observed in QD arrays for both systems at . The emission from the surface level of QDs in the region , formed by the outer atoms with dangling bonds, is observed for the first time, as is the emission band from surface localized states. The relation between the position of the maximum of this band and the energy of the state of the free exciton is established. It is shown that the properties of surface localized states are largely similar to the analogous properties of localized states of 3D (amorphous semiconductors, substitutional solid solutions of substitution) and 2D (quantum wells and superlattices) structures.