Highly a-axis-oriented n- and p-type BaSi2 films were grown on Si(111) substrates by molecular beam epitaxy using Sb and In doping atoms, respectively. The hole concentration of In-doped BaSi2 was controlled in the range between 1016 and 1017 cm-3 at room temperature by changing the temperature of the In Knudsen cell crucible. In contrast, the electron concentration of Sb-doped BaSi2 was controlled in the range between 1016 and 1020 cm-3 by the substrate temperature. The electron and hole mobilities decreased with increasing electron and hole density, respectively.

n-Type BaSi 2 epitaxial films with 900 nm thickness were grown on Si(111) by molecular beam epitaxy, and striped Au electrodes were formed on the surface. Photocurrents were clearly observed for photons with energies greater than 1.25 eV under bias voltages applied between the electrodes, and this increased sharply with increasing photon energy to attain a maximum at approximately 1.70 eV. The external quantum efficiency increased with the bias voltage and reached approximately 7% at 1.70 eV for a bias voltage of 7 V. This value is 100 times larger than the highest value ever reported for semiconducting silicide films. #

Polycrystalline BaSi2 layers with 300 nm thickness were grown by molecular beam epitaxy on (111)-oriented 100-nm-thick polycrystalline Si layers fabricated by an aluminum-induced crystallization method on SiO2. Photocurrents were clearly observed for photons with energies greater than 1.25 eV when bias voltage was applied between the 1.5-mm-spacing striped Al electrodes formed on the surface. The photoresponsivity increased sharply with increasing photon energy, attaining a maximum at approximately 1.60 eV. The external quantum efficiency increased with the bias voltage and reached approximately 8% at 5 V. This value is larger than that obtained for BaSi2 epitaxial films on Si(111).

a b s t r a c tWe have prepared (111)-oriented Si layers on SiO 2 (fused silica) substrates from amorphous-Si(a-Si)/Al or Al/a-Si stacked layers using an aluminum-induced crystallization (AIC) method. The X-ray diffraction (XRD) intensity from the (111) planes of Si was found to depend significantly on growth conditions such as the thicknesses of Si and Al, deposition order (a-Si/Al or Al/a-Si on SiO 2 ), deposition technique (sputtering or vacuum evaporation) and exposure time of the Al layer to air before the deposition of Si.The crystal orientation of the Si layers was confirmed by yÀ2y, 2y XRD and electron backscatter diffraction (EBSD). The photoresponse properties of semiconducting BaSi 2 films formed on the (111)-oriented Si layers by the AIC method were measured at room temperature. Photocurrents were clearly observed for photon energies greater than 1.25 eV. The external quantum efficiencies of the BaSi 2 were also evaluated.

We successfully demonstrated epitaxial growth of semiconductor (BaSi 2 )/metal(CoSi 2 ) Schottky-barrier structures on Si(1 1 1), for the first time, by molecular beam epitaxy (MBE). The interface between the CoSi 2 and BaSi 2 layers was found to be sharp from transmission electron microscopy (TEM) observations. The current-voltage characteristics measured at room temperature showed clear rectifying properties. When positive bias was applied to the CoSi 2 layer with respect to the BaSi 2 layer, the current increased exponentially. Electron diffraction patterns obtained using reflection high-energy electron diffraction (RHEED) and TEM are discussed. r