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The effect of surface states and band bending change on reflectivity of cleaved GaAs(110) and GaP(110)
A108 Surface Science I68 (1986) 1-15 North-Holland. A m s t e r d a m
A T O M I C G E O M E T R I E S OF Z I N C B L E N D E C O M P O U N D SEMICONDUCTOR SURFACES: S I M I L A R I T I E S IN S U R F A C E R E H Y B R I D I Z A T I O N S A. K A H N Department of Electrical Engineering, Princeton Univer,~ity, Princeton. New ,lersev 08544, USA Received 10 June 1985; accepted for publication 14 June 1985 Atomic geometries of zincblende c o m p o u n d semiconductor surfaces are reviewed in the light of recent work done on ( 111 ) and (311 ) G a A s surfaces. The geometries derived from low-energy electron diffraction and from energy-minimization calculations, and electron energy-loss spectroscopy data on surface electronic transitions indicate that the microscopic structures of the (110), ( I l I ) - A and (311)-B surfaces have c o m m o n features and suggest that similar bond rehybridization mechanisms dominate atomic displacements at these surfaces.
Surface Science 168 (1986)16-27 North-Holland, A m s t e r d a m
S O M E R E C E N T R E S U L T S ON L O W - T E M P E R A T U R E OF C L E A V E D Si A N D Ge S U R F A C E S V.A. G R A Z H U L I S
STUDIES
ln,~titute ~)1'Solid State Physics, USSR Academy of Sctence~'. ('hernogolovka, Mos'cow district. I42432, USSR Received I[)June 1985: accepted for publication ]4 June 1985
Atomic structures of Si(ll 1) and Ge(1 II) clean cleaved surfaces at lo~ temperatures (1(~300 K) are discussed. It is experimentally shown that some Iow-Tcleavages can produce strongly disordered G c ( l l l ) - 2 × l surfaces ("amorphous-like" surfaces), however, with some traces of the 2×1 structure. The band bending and the Fermi-level pinning arc als~ briefly considered. It is supposed that near-to-surface dislocations can be introduced during the Ge and Si crystal cleavages and strongly affect the Fermi-level and electronic properties of these cleavages. The possible role of dish)cations in Schottkv barrier formation is also mentioned,
Surface Science I68 (1986) 28- 34 North-Holland, A m s t e r d a m
T H E E F F E C T OF S U R F A C E S T A T E S A N D B A N D B E N D I N G C H A N G E O N R E F L E C T I V I T Y OF C L E A V E D G a A s ( l l 0 ) AND GaP(ll0) F. CICCACCI, S. SELCI and G. C H I A R O U F I Dipartimento di Fisica, Universit~i di Roma "Tor Vergata", Rome. I-O01Z~, Italy
and
A109 P. CHIARADIA
and A. CRICENTI
lstituto di Struttura della Materia del CNR, Via E. Fermi 38, Frascati, 1-00044, Italy Received 10 June 1985; accepted for publication 14 June 1985 New accurate surface differential reflectivity data of the GaAs and GaP cleavage faces are presented. Surface state transitions have been detected near 2.9 eV in G a A s ( l l 0 ) , while in G a P ( l l 0 ) they appear at 2.8 and 3.5 eV. In both cases a small bulk-like Franz-Keldish effect is superimposed on the surface contribution to differential reflectivity. A method for subtracting this term out is described. The relevance of the present results in the context of the debate on surface excitons is also discussed.
Surface Science 168 (1986) 35-45 North-Holland, Amsterdam
O P T I C A L A N D E L E C T R O N E N E R G Y - L O S S S P E C T R A OF S i ( l l l ) 2 × 1 A. SELLONI
and R. DEL
SOLE
Dipartimento di Fisica, 11 Universitg~ di Roma, Rome, Italy Received 10 June 1985; accepted for publication 5 July 1985 We present a method to evaluate the surface reflectivity and use it for Si(111)2× I. Beside the strong anisotropic peak at =0.5 eV, we discuss the origin of the structures observed experimentally in the range 1 < ¢ho ~< 4 eV. We find that a large contribution to these structures comes from surface-assisted, bulk-like, non-direct transitions. A simplified model of surface dielectric tensor - valid in the range h~o < 1 eV - is derived, and applied to discuss electron energy-loss spectra with various primary beam energies E0. In particular we suggest an interpretation of the doublepeaked structure occurring at low E 0 values.
Surface Science 168 (1986) 46-51 North-Holland, Amsterdam
THE EFFECT OF S U R F A C E STRESS O N THE R E C O N S T R U C T I O N OF T H E Si(111) S U R F A C E E. PEARSON,
T. HALICIOGLU
and W.A.
TILLER
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA Received 10 June 1985; accepted for publication 17 July 1985 Stress tensors and their influence on the reconstruction of Si(111) surfaces were calculated using a "statics" computer simulation technique based on a semi-empirical potential energy function. Analyses were aimed at investigating long-range stress interactions on ideal and defective S i ( l l l ) surfaces. Calculations indicate that the perfect S i ( l l l ) surface is under a large compressive stress. Formation of ledges and surface vacancies, in particular, were found to reduce this compressive stress.
A T O M I C G E O M E T R I E S OF Z I N C B L E N D E C O M P O U N D SEMICONDUCTOR SURFACES: S I M I L A R I T I E S IN S U R F A C E R E H Y B R I D I Z A T I O N S A. K A H N Department of Electrical Engineering, Princeton Univer,~ity, Princeton. New ,lersev 08544, USA Received 10 June 1985; accepted for publication 14 June 1985 Atomic geometries of zincblende c o m p o u n d semiconductor surfaces are reviewed in the light of recent work done on ( 111 ) and (311 ) G a A s surfaces. The geometries derived from low-energy electron diffraction and from energy-minimization calculations, and electron energy-loss spectroscopy data on surface electronic transitions indicate that the microscopic structures of the (110), ( I l I ) - A and (311)-B surfaces have c o m m o n features and suggest that similar bond rehybridization mechanisms dominate atomic displacements at these surfaces.
Surface Science 168 (1986)16-27 North-Holland, A m s t e r d a m
S O M E R E C E N T R E S U L T S ON L O W - T E M P E R A T U R E OF C L E A V E D Si A N D Ge S U R F A C E S V.A. G R A Z H U L I S
STUDIES
ln,~titute ~)1'Solid State Physics, USSR Academy of Sctence~'. ('hernogolovka, Mos'cow district. I42432, USSR Received I[)June 1985: accepted for publication ]4 June 1985
Atomic structures of Si(ll 1) and Ge(1 II) clean cleaved surfaces at lo~ temperatures (1(~300 K) are discussed. It is experimentally shown that some Iow-Tcleavages can produce strongly disordered G c ( l l l ) - 2 × l surfaces ("amorphous-like" surfaces), however, with some traces of the 2×1 structure. The band bending and the Fermi-level pinning arc als~ briefly considered. It is supposed that near-to-surface dislocations can be introduced during the Ge and Si crystal cleavages and strongly affect the Fermi-level and electronic properties of these cleavages. The possible role of dish)cations in Schottkv barrier formation is also mentioned,
Surface Science I68 (1986) 28- 34 North-Holland, A m s t e r d a m
T H E E F F E C T OF S U R F A C E S T A T E S A N D B A N D B E N D I N G C H A N G E O N R E F L E C T I V I T Y OF C L E A V E D G a A s ( l l 0 ) AND GaP(ll0) F. CICCACCI, S. SELCI and G. C H I A R O U F I Dipartimento di Fisica, Universit~i di Roma "Tor Vergata", Rome. I-O01Z~, Italy
and
A109 P. CHIARADIA
and A. CRICENTI
lstituto di Struttura della Materia del CNR, Via E. Fermi 38, Frascati, 1-00044, Italy Received 10 June 1985; accepted for publication 14 June 1985 New accurate surface differential reflectivity data of the GaAs and GaP cleavage faces are presented. Surface state transitions have been detected near 2.9 eV in G a A s ( l l 0 ) , while in G a P ( l l 0 ) they appear at 2.8 and 3.5 eV. In both cases a small bulk-like Franz-Keldish effect is superimposed on the surface contribution to differential reflectivity. A method for subtracting this term out is described. The relevance of the present results in the context of the debate on surface excitons is also discussed.
Surface Science 168 (1986) 35-45 North-Holland, Amsterdam
O P T I C A L A N D E L E C T R O N E N E R G Y - L O S S S P E C T R A OF S i ( l l l ) 2 × 1 A. SELLONI
and R. DEL
SOLE
Dipartimento di Fisica, 11 Universitg~ di Roma, Rome, Italy Received 10 June 1985; accepted for publication 5 July 1985 We present a method to evaluate the surface reflectivity and use it for Si(111)2× I. Beside the strong anisotropic peak at =0.5 eV, we discuss the origin of the structures observed experimentally in the range 1 < ¢ho ~< 4 eV. We find that a large contribution to these structures comes from surface-assisted, bulk-like, non-direct transitions. A simplified model of surface dielectric tensor - valid in the range h~o < 1 eV - is derived, and applied to discuss electron energy-loss spectra with various primary beam energies E0. In particular we suggest an interpretation of the doublepeaked structure occurring at low E 0 values.
Surface Science 168 (1986) 46-51 North-Holland, Amsterdam
THE EFFECT OF S U R F A C E STRESS O N THE R E C O N S T R U C T I O N OF T H E Si(111) S U R F A C E E. PEARSON,
T. HALICIOGLU
and W.A.
TILLER
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA Received 10 June 1985; accepted for publication 17 July 1985 Stress tensors and their influence on the reconstruction of Si(111) surfaces were calculated using a "statics" computer simulation technique based on a semi-empirical potential energy function. Analyses were aimed at investigating long-range stress interactions on ideal and defective S i ( l l l ) surfaces. Calculations indicate that the perfect S i ( l l l ) surface is under a large compressive stress. Formation of ledges and surface vacancies, in particular, were found to reduce this compressive stress.