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Ion scattering study of reconstruction in the Au(110)-(1 × 2) surface
A551 Surface Sctence 161 (1985) 567-583 North-Holland, Amsterdam ON THE
INFLUENCE
GROWTH L.J. GILING
567
OF SURFACE
RECONSTRUCTION
ON CRYSTAL
PROCESSES and W.J.P. VAN
ENCKEVORT
R I M Laboratory of Sohd State Chem:stry, Faculty of Scwnce, Cathohc Umvers:ty, Toernooweld, NL-6525 ED Nymegen, The Netherlands Rece,ved 31 August 1984, accepted for pubhcatlon 3 June 1985 Apphcat,on of the morpholog,c Per,od~c Bond Chain method to dlamond-hke crystal structures learns that {001 } faces should be K or S type, I e they will be atomically rough This ~mphes that these cubtc faces should have a very high growth rate and that on these surfaces no steps should appear because the step free energy ts zero However, this ts m conflict with qmte a lot of expertmental evidence, especmlly for the (0Ol } faces of St, Ge, G a A s and diamond wh,ch generally are slowly growing stable faces crowded with growth steps Thts contrad,ctlon can be explained by accepting that under the condttlons where these crystals were grown the (001} surface has reconstructed into the well known ( 2 × 1) reconstruct,on where the surface atoms lower the,r energy by dlmertzaUon and occupy different positrons with respect to the bulk phase Th~s leads to the creation of a step free energy larger than zero and thus to the observed F-hke behav~our It ts demonstrated that the (2 × 1) reconstruction not only is present for the cases under high vacuum condlt,ons, but also can be operattve at normal growth condmons, for instance at 1 bar pressure, where adsorptton mtght play a role Further the lateral ortentattons of growth steps on the { 111 } and (001 } faces of dsamond-hke semtconductor crystals are discussed m terms of reconstruction near or at step stte atoms
584
Surface Sctence 161 (1985) 584-596 North-Holland, Amsterdam
ION SCA'ITERING STUDY OF RECONSTRUCTION Au(ll0)-(l X 2) SURFACE * S.P. WITHROW,
J.H. BARRETT
IN THE
and R.J. CULBERTSON
Sohd State Dwtston, Oak Ridge Nattonal Laboratory, Oak Rtdge, Tennessee 37831, USA Received 19 February 1985, accepted for pubhcatlon 20 May 1985 Structural models for the clean Au(110)-(1 × 2) surface have been evaluated by comparison of calculations to experimental He + backscattermg surface yield measurements Angular scans of the surface yield around the [101] and [100] off-normal axes are asymmetric. These results are m reasonable agreement w~th n u s s m g row surface models lncorporatmg lateral translations tn the second row and either an expansion or contraction of the top layer Energy scans of the on-axts surface yield are consistent w~th these results Lack of agreement between the experimental and calculated w~dths of the angular scans md,cate that the structure models do not completely describe the surface
INFLUENCE
GROWTH L.J. GILING
567
OF SURFACE
RECONSTRUCTION
ON CRYSTAL
PROCESSES and W.J.P. VAN
ENCKEVORT
R I M Laboratory of Sohd State Chem:stry, Faculty of Scwnce, Cathohc Umvers:ty, Toernooweld, NL-6525 ED Nymegen, The Netherlands Rece,ved 31 August 1984, accepted for pubhcatlon 3 June 1985 Apphcat,on of the morpholog,c Per,od~c Bond Chain method to dlamond-hke crystal structures learns that {001 } faces should be K or S type, I e they will be atomically rough This ~mphes that these cubtc faces should have a very high growth rate and that on these surfaces no steps should appear because the step free energy ts zero However, this ts m conflict with qmte a lot of expertmental evidence, especmlly for the (0Ol } faces of St, Ge, G a A s and diamond wh,ch generally are slowly growing stable faces crowded with growth steps Thts contrad,ctlon can be explained by accepting that under the condttlons where these crystals were grown the (001} surface has reconstructed into the well known ( 2 × 1) reconstruct,on where the surface atoms lower the,r energy by dlmertzaUon and occupy different positrons with respect to the bulk phase Th~s leads to the creation of a step free energy larger than zero and thus to the observed F-hke behav~our It ts demonstrated that the (2 × 1) reconstruction not only is present for the cases under high vacuum condlt,ons, but also can be operattve at normal growth condmons, for instance at 1 bar pressure, where adsorptton mtght play a role Further the lateral ortentattons of growth steps on the { 111 } and (001 } faces of dsamond-hke semtconductor crystals are discussed m terms of reconstruction near or at step stte atoms
584
Surface Sctence 161 (1985) 584-596 North-Holland, Amsterdam
ION SCA'ITERING STUDY OF RECONSTRUCTION Au(ll0)-(l X 2) SURFACE * S.P. WITHROW,
J.H. BARRETT
IN THE
and R.J. CULBERTSON
Sohd State Dwtston, Oak Ridge Nattonal Laboratory, Oak Rtdge, Tennessee 37831, USA Received 19 February 1985, accepted for pubhcatlon 20 May 1985 Structural models for the clean Au(110)-(1 × 2) surface have been evaluated by comparison of calculations to experimental He + backscattermg surface yield measurements Angular scans of the surface yield around the [101] and [100] off-normal axes are asymmetric. These results are m reasonable agreement w~th n u s s m g row surface models lncorporatmg lateral translations tn the second row and either an expansion or contraction of the top layer Energy scans of the on-axts surface yield are consistent w~th these results Lack of agreement between the experimental and calculated w~dths of the angular scans md,cate that the structure models do not completely describe the surface