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Transient growth in molecular beam epitaxy of Si on Si(100) vicinal surfaces
A248 Surface Science 283 (1993) 349 354 North-Holland
Incommensurate phase of Sn/Si(100) studied by HR-REM Y. Kimura and K. Takayanagi l)epartment of Materials Science and Engineering. Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 227, Japan Received 21 April 1992; accepted for publication 6 May 1992 Coverage dependent surface phases of Sn deposited on the Si(100) surface are observed by reflection electron microscopy (REM). As the coverage is decreased from monolayer coverage at 400°C, two kinds of phases are found. One is the admixture of n-fold (5 < n < 11) superstructures found in a wide coverage range: Spacing of the superlattice fringes seen locally in the high-resolution REM (HR-REM) images varies from place to place, while superlattice spots in RHEED patterns are of an average value p of the superstructure period n. The RHEED patterns show always half order spots, which indicates that the Sn layer has a twofold periodicity parallel to the dimer row of the 2 × 1 structure of the Si(100) surface. The other is an incommensurate phase of a superlattice period p = 6.7 _+~ (0_< 6 < 0.2), formed at a certain coverage. The phase is well-ordered: the corresponding superlattice fringes observed in the REM image have a uniform spacing. In this phase, no half order spots appear in the RHEED pattern, indicating the disappearance of the twofold periodicity in the incommensurate Sn layer.
Surface Science 283 (1993) 355-359 North-Holland
Combined Raman/HREELS study of ZnSe-ZnS strained-layer superlattices M. Sekoguchi, Y. Uehara and S. Ushioda Research Institute of Electrical Communication, Tohoku University, Sendai 980, Japan Received 21 April 1992; accepted for publication 23 April 1992 ZnSe-ZnS strained-layer superlattices have been investigated by combining Raman scattering and high-resolution electron energy loss spectroscopy (HREELS). The superlattices were grown on GaAs(001) by MOCVD without a buffer layer. Epitaxial growth of the superlattices was confirmed by the polarization selection rule of Raman scattering. Energy differences between the bulk (ZnS, ZnSe) LO phonons and the superlattice LO phonons indicate that strain is mainly localized in the ZnS layers. In HREELS the loss peak originating from ZnS must be assumed to be appreciably weaker than that from ZnSe. This result does not agree with the theoretical prediction based on the dielectric theory. We conclude that the reduction of the electron scattering intensity results from large strain in the ZnS layers.
Surface Science 283 (1993) 360-365 North-Holland
Transient growth in molecular beam epitaxy of Si on Si(100) vicinal surfaces T. Kawamura a,. and M.R. Wilby b,. "Department of Physics, Yamanashi University, Kofu, Yamanashi 400, Japan b Department of Physics, Imperial College, London SW7 2BZ, UK Received 21 April 1992; accepted for publication 17 August 1992 During Si molecular beam epitaxy on a Si(100) vicinal surface with monatomic height steps, we have found a transient mode which shows a characteristic behaviour in the coverage of 2 × 1 terraces. The mode consists of two competitive growth modes: a step flow growth mode and a two-dimensional nucleation growth mode. The two modes appear alternatively depending on the 2 × 1 terrace area which varies during the growth.
Incommensurate phase of Sn/Si(100) studied by HR-REM Y. Kimura and K. Takayanagi l)epartment of Materials Science and Engineering. Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 227, Japan Received 21 April 1992; accepted for publication 6 May 1992 Coverage dependent surface phases of Sn deposited on the Si(100) surface are observed by reflection electron microscopy (REM). As the coverage is decreased from monolayer coverage at 400°C, two kinds of phases are found. One is the admixture of n-fold (5 < n < 11) superstructures found in a wide coverage range: Spacing of the superlattice fringes seen locally in the high-resolution REM (HR-REM) images varies from place to place, while superlattice spots in RHEED patterns are of an average value p of the superstructure period n. The RHEED patterns show always half order spots, which indicates that the Sn layer has a twofold periodicity parallel to the dimer row of the 2 × 1 structure of the Si(100) surface. The other is an incommensurate phase of a superlattice period p = 6.7 _+~ (0_< 6 < 0.2), formed at a certain coverage. The phase is well-ordered: the corresponding superlattice fringes observed in the REM image have a uniform spacing. In this phase, no half order spots appear in the RHEED pattern, indicating the disappearance of the twofold periodicity in the incommensurate Sn layer.
Surface Science 283 (1993) 355-359 North-Holland
Combined Raman/HREELS study of ZnSe-ZnS strained-layer superlattices M. Sekoguchi, Y. Uehara and S. Ushioda Research Institute of Electrical Communication, Tohoku University, Sendai 980, Japan Received 21 April 1992; accepted for publication 23 April 1992 ZnSe-ZnS strained-layer superlattices have been investigated by combining Raman scattering and high-resolution electron energy loss spectroscopy (HREELS). The superlattices were grown on GaAs(001) by MOCVD without a buffer layer. Epitaxial growth of the superlattices was confirmed by the polarization selection rule of Raman scattering. Energy differences between the bulk (ZnS, ZnSe) LO phonons and the superlattice LO phonons indicate that strain is mainly localized in the ZnS layers. In HREELS the loss peak originating from ZnS must be assumed to be appreciably weaker than that from ZnSe. This result does not agree with the theoretical prediction based on the dielectric theory. We conclude that the reduction of the electron scattering intensity results from large strain in the ZnS layers.
Surface Science 283 (1993) 360-365 North-Holland
Transient growth in molecular beam epitaxy of Si on Si(100) vicinal surfaces T. Kawamura a,. and M.R. Wilby b,. "Department of Physics, Yamanashi University, Kofu, Yamanashi 400, Japan b Department of Physics, Imperial College, London SW7 2BZ, UK Received 21 April 1992; accepted for publication 17 August 1992 During Si molecular beam epitaxy on a Si(100) vicinal surface with monatomic height steps, we have found a transient mode which shows a characteristic behaviour in the coverage of 2 × 1 terraces. The mode consists of two competitive growth modes: a step flow growth mode and a two-dimensional nucleation growth mode. The two modes appear alternatively depending on the 2 × 1 terrace area which varies during the growth.