Epitaxial growth of Si on top of a boron-adsorbed Si(111) surface was studied in a molecular beam epitaxy (MBE) system. When the initial boron coverage was more than 1/3 monolayer (ML), reflection high-energy electron diffraction (RHEED) intensity oscillation showed a 4 ML period in the early stage of Si growth as long as surface-segregated boron at the growing surface was more than 1/3 ML, and turned to the normal 2 ML period of oscillation. Periodical change of the full width at half-maximum (FWHM) of the RHEED specular spot confirmed that this is due to two-dimensional island growth of 4 ML height and the coalescence mode of Si.

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We measure the large-scale cross-correlation of quasars with the Lyα forest absorption, using over 164,000 quasars from Data Release 11 of the SDSS-III Baryon Oscillation Spectroscopic Survey. We extend the previous study of roughly 60,000 quasars from Data Release 9 to larger separations, allowing a measurement of the Baryonic Acoustic Oscillation JCAP05 (2014)027 (BAO) scale along the line of sight c/(H(z = 2.36) r s ) = 9.0 ± 0.3 and across the line of sight D A (z = 2.36) / r s = 10.8 ± 0.4, consistent with CMB and other BAO data. Using the best fit value of the sound horizon from Planck data (r s = 147.49 Mpc), we can translate these results to a measurement of the Hubble parameter of H(z = 2.36) = 226 ± 8 km s −1 Mpc −1 and of the angular diameter distance of D A (z = 2.36) = 1590 ± 60 Mpc. The measured cross-correlation function and an update of the code to fit the BAO scale (baofit) are made publicly available.

Adsorption of boron on Si(111) surface during HBO2 irradiation was evaluated by reflection high-energy electron diffraction (RHEED). At the substrate temperature above 700°C, RHEED specular beam intensity decreased to a minimum value at boron coverage of 1/3 monolayer (ML), and then increased to the initial value (1 ML coverage). On the other hand, when the substrate temperature was below 700°C, intensity did not recover to the initial value due to the simultaneous surface oxidation. From the temperature dependence of the adsorption rate, the activation energy of the boron adsorption on Si(111) surface was estimated to be 1.2 eV.

Heteroepitaxy of Ge was performed onto clean Si(111)7×7 and 1-monolayer (ML) boron-preadsorbed Si(111)√ 3×√ 3R30°–B surfaces held at 500° C. Both cases of growth showed the Stranski-Krastanov (SK) growth mode. On the clean surface, layer-by-layer growth by 2-ML-height two-dimensional (2D) islands lasted for up to 6 ML of Ge growth, and then relaxed 3D islands began to be formed. On the boron-preadsorbed surface, however, critical thickness for the formation of 3D islands increased to 8 ML due to suppression of Ge surface migration by surface-segregated boron atoms. It was confirmed by atomic force microscopy (AFM) that the height of 2D islands appearing in the layer-by-layer growth process changed from the normal 2 ML to 4 ML on the boron-preadsorbed surface.