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Using the electron spin resonance (ESR) method, conductance measurements, and small-angle X-ray scattering (SAXS), the properties of nanoporous carbon (NPC) containing atoms of Ni in the pores are studied in comparison with the nickel-free NPC studied before. Although the amount of Ni introduced into the nanopores is small, the NPC properties change significantly. The ESR spectra show that, at low temperatures, the charge carriers are captured at the localized states. The bulk ferromagnetism is not observed at temperatures as low as 3.2 K. Magnetic properties are strongly temperature dependent and are not limited by the paramagnetism of free charge carriers. The temperature dependence of the ESR resonance field indicates the influence of ferromagnetic inclusions. The ferromagnetic shift of the resonance fields is observed up to a temperature of 80 K. The temperature dependence of the conductance reveals an exponential growth with the activation energy close to those obtained from the ESR measurements. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Paper presents an overview of recent results on novel CdSe quantum dot (QD) fabrication techniques with the main impact on a stressor-controlled self-organization process resulting in nucleation of real CdSe QDs optically active up to room temperature, with a narrower size distribution, a higher density and a high Cd content. The main idea of the stressor-controlled epitaxy is an intentional introduction of a super-strained fractional monolayer of the much higher lattice-mismatch compound - stressor - to create strong local stress fields on the growth surface which govern self-assembling of the main QD material. The studies are performed on a type-II non-common atom CdSe/BeTe system, where CdTe (Δa/a ∼ +14%) and BeSe (Δa/a ∼ -10%) interface bonds play a role of intrinsic stressors. Both experimental data (growth, structural and optical characterization) and Monte Carlo simulation of the growth process are presented.

We report on optical and structural studies of the interface symmetry in CdSe/BeTe multiple-layer structures containing self-assembled quantum dots. Temperature and decay behavior of the broad photoluminescence (PL) band is consistent with the type-II transitions involving deeply localized electron states. Large linear in-plane polarization of the PL (up to 80%) is observed, implying the C-2v (or lower) symmetry of the individual places of the electron localization.