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The growth of Si and Ge on silicon nitride surfaces has been investigated using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and Auger electron spectrometer (AES). In the early stages, Si or Ge nanoclusters appeared irrespective of the different substrates. When annealed, the Si clusters were more stable against coalescence than those of Ge. As these clusters continued to grow, crystalline facets started to form. Both Si and Ge islands grew predominantly with (111)-oriented top facets on the crystalline Si3N4(0001)/Si(111). By contrast, they both grew in random orientation on the amorphous Si3N4 surface. Low-index facets such as (111) and (001) coexisted with high-index facets such as (113). [ABSTRACT FROM AUTHOR]

MnSb nanocrystallites and thin films have been grown on highly oriented pyrolytic graphite (HOPG) by codeposition of Mn and Sb in ultrahigh vacuum. The surface morphologies of these MnSb structures were investigated using in situ scanning tunneling microscopy (STM). With 5 nm nominal deposition, MnSb nanocrystallite chains with a typical width of 50 nm are formed along the HOPG step edges. A continuous MnSb film is formed after Mn and Sb codeposition on a HOPG precovered with an Sb wetting layer. The MnSb thin film surface exhibits mostly hexagonal-shaped MnSb(0001) plateaus of a few atomic layers in height. Atomic-resolution STM images revealed 2×2 and (23×23)R30° reconstructions on the MnSb(0001) surface and a 2×1 superstructure on MnSb(1011). X-ray photoelectron spectroscopy study showed that the Mn 2p peaks shift 2.5 eV with respect to that of elemental Mn, indicating the formation of MnSb compound. Vibrating sample magnetometry measurement showed that the MnSb film is ferromagnetic at room temperature, and is composed of mostly (0001)-oriented grains as well as some with other orientations. [ABSTRACT FROM AUTHOR]

Germanium was deposited onto highly oriented pyrolytic graphite (HOPG) with and without antimony in ultra-high vacuum. The surface morphology was analyzed using in situ scanning tunneling microscopy (STM) at room temperature (RT). The film grows exclusively in 3D island mode and was affected significantly by substrate defects. At initial stage, nucleation of cluster occurred at step edges and defect sites. Later, we found various types of Ge nanostructures on HOPG in different deposition conditions and stages, including cluster chains, cluster islands, nanowires, and double layer ramified islands at RT. Compact Ge islands were observed when depositing at a substrate temperature of 450 K or after an annealing at 600 K following RT deposition. In addition, the pre-deposited Sb on graphite enhances the sticking probability and suppresses the surface diffusion of Ge atoms, resulting in a significant increase in Ge cluster island density on HOPG terraces. [ABSTRACT FROM AUTHOR]