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The molecular beam epitaxial growth of PbTe nanowires on GaAs(111)B substrates is reported. The growth process was based on the Au-catalyzed vapor−liquid−solid mechanism. These nanowires grow along the [100] axis; they are perpendicular to the substrate, have tapered shapes, and have diameters of about 90 nm at the base and 60 nm at the top. High resolution transmission electron microscopy pictures reveal that the PbTe nanowires have a rock-salt structure and, in contrast to the one-dimensional structures of III−V and II−VI compound semiconductors such as GaAs, InAs, or ZnTe, are free from stacking faults. A theoretical analysis of these experimental findings, which is based on ab initio modeling of the PbTe nanowires, is also presented.

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Experimental measurements of low-temperature electron transport across Si nanogratings with 200 nm period are reported. The structure is fabricated of silicon on insulator layer using laser interference lithography followed by reactive ion etching. For transport measurements, macroscopic Hall bar formed in the patterned layer is used. The main result is negative magnetoresistance observed for temperatures lower than 60 K and not saturating in magnetic fields up to 9 Tesla. It is interpreted in terms of weak localization suppression and fit the magnetoresistance curves by both the two-dimensional and three-dimensional theoretical models. Surprisingly, both models describe satisfactorily the data and thus the problem of dimensionality remains unsettled. However, obtained values of the phase coherence lengths are significantly smaller than both the nanograting period and layer thickness, indicating that the dominant scattering mechanism is not result of the nanostructure geometry.

843 09 26Ferromagnetic transition and magnetic anisotropy was studied by SQUID magnetometry and ferromagnetic resonance (FMR) methods in polycrystalline Ge 1-x Mn x Te (x ¼ 0.085) semiconductor microstructures embedded in an amorphous, insulating, and paramagnetic (Ge,Mn)Te matrix. The microstructures were produced by pulsed laser and electron beam induced local re-crystallization of amorphous layers deposited on insulating BaF 2 substrates. The angular dependence of the FMR resonance field observed below the Curie temperature T C ¼ 70 K of the microstructures is quantitatively described by the analysis of Zeeman and demagnetization contributions to magnetic free energy. Good agreement with experimental results obtained in the case of structures produced by pulsed laser re-crystallization indicates the formation of ferromagnetic (Ge,Mn)Te thin disks of submicron dimensions.