Spontaneous formation of monocrystalline nanostripes in the molecular beam epitaxy of antimony triselenide.

Self-assembled, highly anisotropic nanostructures are spontaneously formed in the molecular beam epitaxy of antimony triselenide on GaAs substrates. These one-dimensional (1D) nanostripes have all the orientations parallel to the substrate surface and preserve the epitaxial relationship with the substrate. The shape of the nanostripes is directly related to the highly anisotropic stibnite structure of antimony triselenide which consists of 1D ribbons held together by weak van der Waals forces. The fabrication of well-ordered arrays of horizontal nanostripes aligned in directions defined by the orientation of the substrate may contribute significantly to the development of electronic circuits and networks composed of interconnected nanostructures leading to applications in neuromorphic devices, gas sensors and polarization-sensitive photodetectors.

Chemical vapor deposition of germanium-rich CrGe x nanowires.

Chemical vapor deposition was applied to synthetize nanostructured deposits containing several sorts of nanoobjects (i.e., nanoballs, irregular particles, and nanowires). Analytical techniques, that is, high-resolution transmission electron microscopy, scanning electron microscopy, electron dispersive X-ray analysis, selected area electron diffraction, and X-ray photoelectron spectroscopy, showed that unlike nanoballs and particles composed of crystalline germanium, the layer was made of chromium germanide CrGe x . The nanowires possessed a complex structure, namely a thin crystalline germanium core and amorphous CrGe x coating. The composition of the nanowire coating was [Cr]/[Ge] = 1:(6-7). The resistance of the nanowire-deposit system was estimated to be 2.7 kΩ·cm using an unique vacuum contacting system.

Highly Rectifying Heterojunctions Formed by Annealed ZnO Nanorods on GaN Substrates.

We study the effect of thermal annealing on the electrical properties of the nanoscale p-n heterojunctions based on single n-type ZnO nanorods on p-type GaN substrates. The ZnO nanorods are prepared by chemical bath deposition on both plain GaN substrates and on the substrates locally patterned by focused ion beam lithography. Electrical properties of single nanorod heterojunctions are measured with a nanoprobe in the vacuum chamber of a scanning electron microscope. The focused ion beam lithography provides a uniform nucleation of ZnO, which results in a uniform growth of ZnO nanorods. The specific configuration of the interface between the ZnO nanorods and GaN substrate created by the focused ion beam suppresses the surface leakage current and improves the current-voltage characteristics. Further improvement of the electrical characteristics is achieved by annealing of the structures in nitrogen, which limits the defect-mediated leakage current and increases the carrier injection efficiency.