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Surface confined phonons in semiconductor superlattices
A122 354
Surface Science 211/212 (1989) 354-360 North-Holland, Amsterdam
SURFACE C O N F I N E D P H O N O N S IN SEMICONDUCTOR SUPERLATrlCES L. S O R B A ,
E. M O L I N A R I
CNR, lstttuto di Acustica "O.M. ('orbino", Via (~asxta 1216, 1-00189 Roma, ltalv and A. F A S O L I N O S1SSA, Strada Costiera 11, 1 34100 Trieste, Italy Received 18 June 1988; Accepted for publication 18 October 1988 We show that the phonon spectra of finite GaAs/A1As(001) superlattices along their growth direction display a new type of confined surface modes which split off the superlattice confined optical branches. Their frequency location and decay inside the superlattice is investigated by means of a model calculation and compared with the behaviour of surface states of semi-infinite GaAs.
Surface Science 211/212 (1989) 361 367 North-Holland, Amsterdam
361
LOVE A N D S H E A R H O R I Z O N T A L INTERFACE W A V E S IN A SUPERLA'IWICE D E P O S I T E D ON A S U B S T R A T E E. K H O U R D I F I
a n d B. D J A F A R I
ROUHANI
Laboratoire de Physique du Solide, Facult~ des Sciences et Techniques, Universit~ de Haute Alsace, 4, rue des Frbres Lumidre, 68093 Mulhouse Cedex, France Received 14 June 1988; accepted for publication 23 September 1988 The existence of shear horizontal interface vibrations localized at the boundary between a substrate and a semi-infinite superlattice made of alternating layers of two elastic media is investigated theoretically. It is shown that in contrast to the case of an interface between two homogeneous media, such localized waves may appear inside the gaps of the superlattice (resulting from the folding of the Brillouin zone along the superlattice axis) and even below the bottom of the bulk bands. Their existence and dispersion are dependent upon the relative parameters of the superlattice and the substrate, but also upon the nature of the film in the superlattice which is in contact with the substrate. We also investigate the behaviour of the Love waves when a finite superlattice is deposited on a substrate as a function of the superlattice thickness and of the wave vector k II parallel to the layers.
Surface Science 211/212 (1989) 354-360 North-Holland, Amsterdam
SURFACE C O N F I N E D P H O N O N S IN SEMICONDUCTOR SUPERLATrlCES L. S O R B A ,
E. M O L I N A R I
CNR, lstttuto di Acustica "O.M. ('orbino", Via (~asxta 1216, 1-00189 Roma, ltalv and A. F A S O L I N O S1SSA, Strada Costiera 11, 1 34100 Trieste, Italy Received 18 June 1988; Accepted for publication 18 October 1988 We show that the phonon spectra of finite GaAs/A1As(001) superlattices along their growth direction display a new type of confined surface modes which split off the superlattice confined optical branches. Their frequency location and decay inside the superlattice is investigated by means of a model calculation and compared with the behaviour of surface states of semi-infinite GaAs.
Surface Science 211/212 (1989) 361 367 North-Holland, Amsterdam
361
LOVE A N D S H E A R H O R I Z O N T A L INTERFACE W A V E S IN A SUPERLA'IWICE D E P O S I T E D ON A S U B S T R A T E E. K H O U R D I F I
a n d B. D J A F A R I
ROUHANI
Laboratoire de Physique du Solide, Facult~ des Sciences et Techniques, Universit~ de Haute Alsace, 4, rue des Frbres Lumidre, 68093 Mulhouse Cedex, France Received 14 June 1988; accepted for publication 23 September 1988 The existence of shear horizontal interface vibrations localized at the boundary between a substrate and a semi-infinite superlattice made of alternating layers of two elastic media is investigated theoretically. It is shown that in contrast to the case of an interface between two homogeneous media, such localized waves may appear inside the gaps of the superlattice (resulting from the folding of the Brillouin zone along the superlattice axis) and even below the bottom of the bulk bands. Their existence and dispersion are dependent upon the relative parameters of the superlattice and the substrate, but also upon the nature of the film in the superlattice which is in contact with the substrate. We also investigate the behaviour of the Love waves when a finite superlattice is deposited on a substrate as a function of the superlattice thickness and of the wave vector k II parallel to the layers.