A411

Surface Science 189/190 (1987) 353-361 353 North-Holland, Amsterdam

A S T U D Y OF T H E R M A L O X I D E - I n P INTERFACES E. B E R G I G N A T , G. H O L L I N G E R

Laboratoire d'Electronique, Ecole Centrale de l~yon, 69131 Ecullv Cedex. France and lnstitut de Physique Nucl~aire de Lyon, 69622 Villeurbanne Cedex, France

a n d

Y. R O B A C H

Laboratoire de Physicochimie des Interfaces, Ecole Centrale de Lyon, 69131 Ecully Cedex, France

Received 13 April 1987; accepted for publication 29 May 1987

XPS and spectroscopic ellipsometry combined to chemical etching depth profiling techniques have been used to study the chemical composition of thin oxide films thermally grown on InP(100) in the 250-550 °C range. It is shown that oxides are made up of a microscopic mixture of In 203 and InPO 4 with elemental P at the interface.

362 Surface Science 189/190 (1987) 362-372 North-Holland, Amsterdam

THE P R O B L E M OF H E T E R O J U N C T I O N B A N D D I S C O N T I N U I T I E S P. P E R F E T T I

L~tituto dt Struttura della Materia (CNR), ~,ia E. Fermi 38, 00044 Frascati, Italy

Received 2 April 1987; accepted for publication 15 April 1987

The valence and conduction band discontinuities, AE v and AE c, result from the different energy gaps of the two semiconductors forming a heterojunction. The problem of how the gap difference is shared between ~ Ev and A E~ is analyzed in terms of the current theoretical linear models. Microscopic factors, as interfacial electrostatic dipoles, play an important role in determining the heterojunction discontinuities. Examples of artificial dipoles, created by ultrathin intralayers of materials inserted between the two semiconductors, will be presented for a large number of interfaces.

Surface Science 189/190 (1987) 373-378 373 North-Holland, Amsterdam

INVESTIGATION OF INTERFACES BY HIGH R E S O L U T I O N ELECTRON ENERGY L O S S S P E C T R O S C O P Y P.A. T H I R Y , M. L I E H R *, J.J. P I R E A U X ~" * a n d R. C A U D A N O

Laboratoire lnterddpartemental de Spectroscopie Electronique, Institut de Recherche sur les Interfaces Solides, FacultOs Universitaires Notre-Dame de la Paix, B-5000 Namur, Belgium

Received 6 April 1987; accepted for publication 15 April 1987

Recent measurements performed on epitaxial layers clearly demonstrate the capability of HREELS to observe interface optical phonons in dielectric layered materials. Two examples are presented: First, the case of epitaxial CaF 2 on Si(111) where the CaF 2 interface phonon is detected

A 4 1 2

for a whole range of CaF 2 layer thicknesses. Discrepancies with theoretical predictions are interpreted as resulting from the residual strain in the CaF 2 layers. The second example is a Ill V semiconductor superlattice GaAs-A1GaAs in which an AI -As type interface mode is clearly identified and quantitatively interpreted by the dielectric theory.

Surface Science 189/190 I1987) 379-384 379 North-Holland, Amsterdam

STRAIN-AFFECTED BAND OFFSETS AT S i / S i t - .,.Ge~(100) HETEROJUNCTION INTERFACES STUDIED WITH X-RAY PHOTOEMISSION W . - X . N I , J. K N A L L a n d G . V . H A N S S O N

Department of Physic~ and Measurement Technology, Linki)ping Unil~ersity. S-581 83 l,mkikping, Sweden Received 30 March 1987, accepted for publication 30 April 1987

The band offsets at strained Si/Si I ,Ge,(100) heterojunction interfaces have been studied by X-ray photoemission in combination with ion beana doping during MBE growth. Both A E~ and A E, derived from the core level spectroscopy measurements show large differences in band lineup for heterostructures grown with different strain configurations. The results are in good agreement with published calculations of band offsets.

Surface Science 189/190 (1987) 385-392 North-Holland, Amsterdam

TEMPERATURE DEPENDENCE OF C - V AND G- V CHARACTERISTICS OF NATIVE OXIDE-GaAs INTERFACES OF {111) AND (10t)) ORIENTATIONS

A . M . N A R S A L E *

IRST, 38050 Pouo, Trento, Italy

a n d

B . M . A R O R A

Tata Institute of Fundamental Research, 400005 Bombay, India

Received 30 March 1987; accepted for publication 15 April 1987

385

Capacitance-voltage ( C - V ) and conductance-vol tage ( G - V ) measurements are done at various temperatures on anodically oxidised n-GaAs MOS structures of (111) and (100) orientations. The different behaviour of the C - V and G - V characteristics observed in these samples indicate that the interfacial region differs depending on the orientation.