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Electronic structure of Si(111) surfaces
A328 Surface Science 99 (1980) 1 - 1 2 © North-Holland Publishing Company ATOMIC STRUCTURE OF Si(111) SURFACES D.J. C H A D I
Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, California 94304, USA Received 28 January 1980 Recent experimental and theoretical work on S i ( l l l ) 1 X 1, 2,× 1, and 7 × 7 relaxed and reconstructed surfaces is reviewed. A new, buckled model for the 7 X 7 surface is proposed and its compatibility with a variety of experimental results is examined.
Surface Science 99 (1980) 1 3 - 2 7 © North-Holland Publishing Company E L E C T R O N I C S T R U C T U R E O F S i ( l 11) S U R F A C E S G.V. H A N S S O N , R.Z. B A C H R A C H , R.S. B A U E R , D.J. C H A D I a n d W. G O P E L Xerox Palo Alto Research Center, 3:733 Coyote Hill Road, Palo Alto, California 94304, USA Received 26 November 1979 ; accepted for publication 18 February 1980 We report on new angle-resolved photoemission studies of Si(111) 2 × 1 and 7 X 7 surfaces. The emission from the 2 × 1 surface shows much structure. For normal emission the energy positions are insensitive to the photon energy in the range 1 9 - 2 7 eV. The emission has been interpreted as a probe of the surface density of states, SDOS, including both surface states, resonances and bulk-like states. The SDOS was also calculated as a function of parallel momentum k# for a model of the Si(111) 2 X I surface obtained from energy minimization considerations. We identify emission from the dangling bond band, which has a positive dispersion of 0.6 eV, and also emission from surface resonances which have some character of the compressed and stretched back bonds. There are also other predicted surface resonances that correspond to experimental peaks which have not been identified in previous work. Except for the dangling bond band, the surface resonances are limited in k I space, so that it is not possible to follow these resonance bands over all angles. Maximum intensity for the normal emission from the dangling bond is obtained at 23 eV, while the emission from the lowest s-like states monotonically increases towards 30 eV photon energy. When annealing t h e cleaved 2 X 1 surface to the 7 × 7 reconstructed surface, the spectra broaden significantly. The intensity of the dangling bond decreases and we see a very small metallic edge.
Surface Science 99 (1980) 2 8 - 3 3 © North-Holland Publishing Company
ANGLE-RESOLVED PIIOTOEMISSlON OF TIlE Si(111) 7 X 7 SURFACE F. H O U Z A Y *, G.M. G U I C H A R , R. P I N C H A U X , P. T H I R Y , Y. P E T R O F F a n d D. D A G N E A U X LURE, Bdt. 209c, Universit~ Paris-Sud, F-91405 Orsay Cedex, France and Laboratoire de Physique des Solides, Universitd P. et M. Curie, 4, Place Jussieu, F- 75230 Paris Cede× 05, France Received 12 December 1979; accepted for publication 7 February 1980 Angle-resolved photoemission measurements have been performed on (7 × 7) Si surfaces as a function of the photon energy between 21 and 87 eV at normal emergence for both s- and
Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, California 94304, USA Received 28 January 1980 Recent experimental and theoretical work on S i ( l l l ) 1 X 1, 2,× 1, and 7 × 7 relaxed and reconstructed surfaces is reviewed. A new, buckled model for the 7 X 7 surface is proposed and its compatibility with a variety of experimental results is examined.
Surface Science 99 (1980) 1 3 - 2 7 © North-Holland Publishing Company E L E C T R O N I C S T R U C T U R E O F S i ( l 11) S U R F A C E S G.V. H A N S S O N , R.Z. B A C H R A C H , R.S. B A U E R , D.J. C H A D I a n d W. G O P E L Xerox Palo Alto Research Center, 3:733 Coyote Hill Road, Palo Alto, California 94304, USA Received 26 November 1979 ; accepted for publication 18 February 1980 We report on new angle-resolved photoemission studies of Si(111) 2 × 1 and 7 X 7 surfaces. The emission from the 2 × 1 surface shows much structure. For normal emission the energy positions are insensitive to the photon energy in the range 1 9 - 2 7 eV. The emission has been interpreted as a probe of the surface density of states, SDOS, including both surface states, resonances and bulk-like states. The SDOS was also calculated as a function of parallel momentum k# for a model of the Si(111) 2 X I surface obtained from energy minimization considerations. We identify emission from the dangling bond band, which has a positive dispersion of 0.6 eV, and also emission from surface resonances which have some character of the compressed and stretched back bonds. There are also other predicted surface resonances that correspond to experimental peaks which have not been identified in previous work. Except for the dangling bond band, the surface resonances are limited in k I space, so that it is not possible to follow these resonance bands over all angles. Maximum intensity for the normal emission from the dangling bond is obtained at 23 eV, while the emission from the lowest s-like states monotonically increases towards 30 eV photon energy. When annealing t h e cleaved 2 X 1 surface to the 7 × 7 reconstructed surface, the spectra broaden significantly. The intensity of the dangling bond decreases and we see a very small metallic edge.
Surface Science 99 (1980) 2 8 - 3 3 © North-Holland Publishing Company
ANGLE-RESOLVED PIIOTOEMISSlON OF TIlE Si(111) 7 X 7 SURFACE F. H O U Z A Y *, G.M. G U I C H A R , R. P I N C H A U X , P. T H I R Y , Y. P E T R O F F a n d D. D A G N E A U X LURE, Bdt. 209c, Universit~ Paris-Sud, F-91405 Orsay Cedex, France and Laboratoire de Physique des Solides, Universitd P. et M. Curie, 4, Place Jussieu, F- 75230 Paris Cede× 05, France Received 12 December 1979; accepted for publication 7 February 1980 Angle-resolved photoemission measurements have been performed on (7 × 7) Si surfaces as a function of the photon energy between 21 and 87 eV at normal emergence for both s- and