HAL Id: jpa-00223552
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Submitted on 1 Jan 1983
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ELLIPSOMETRIC STUDY OF THE CLEAVED GERMANIUM (111) SURFACE AS A FUNCTION OF
TEMPERATURE
G. Quentel, R. Kern
To cite this version:
G. Quentel, R. Kern. ELLIPSOMETRIC STUDY OF THE CLEAVED GERMANIUM (111) SUR-
FACE AS A FUNCTION OF TEMPERATURE. Journal de Physique Colloques, 1983, 44 (C10),
pp.C10-473-C10-473. �10.1051/jphyscol:19831094�. �jpa-00223552�
JOURNAL DE PHYSIQUE
Colloque CIO, supplement au n°12, Tome 44, decembre 1983 page C10-473
ELLIPSOMETRIC STUDY OF THE CLEAVED GERMANIUM (.111) SURFACE AS A FUNCTION OF TEMPERATURE
G. Quentel and R. Kern
CRMC2 - CURS, Campus de Luminy, Case 913, 13288 Marseille Cedex 09, France
Résumé - La méthode e l l i p s o m ë t r i q u e , r e l a t i v e m e n t f a c i l e à u t i l i s e r , e s t t r è s sensible à t o u t e m o d i f i c a t i o n e t p e r t u r b a t i o n pouvant se p r o d u i r e sur une surface c r i s t a l l i n e . Dans l e cas des semiconducteurs ( G e , S i ) , l a p e r t u r b a t i o n de l a s u r - face peut a v o i r d i f f é r e n t e s o r i g i n e s . Typiquement, l e s e f f e t s de température con- d u i s e n t à des m o d i f i c a t i o n s de s t r u c t u r e de surface ( r e c o n s t r u c t i o n ) de
Ge (111) 2 x 8 (ou Si (111) 7 x 7 ) .
Nous avons étudié optiquement l a t r a n s i t i o n de surface 2 x l - » 2 x 8 d u Germanium en f o n c t i o n de l a température (300 K<T<700 K).
D'une p a r t , nous avons montré que l a v a r i a t i o n avec l a température de l ' é n e r g i e de l a bande i n t e r d i t e Eg a une f o r t e i n f l u e n c e sur les constantes optiques de surface des semiconducteurs. Le bon accord e n t r e les mesures e l l i p s o m é t r i q u e s effectuées en f o n c t i o n de l a température e t c e l l e s obtenues par a i l l e u r s à longueur d'onde v a r i a b l e , m o n t r e que les t r a n s i t i o n s optiques correspondent aux mêmes bandes d ' é n e r - gie dans l e domaine de température considéré.
D'autre p a r t , des mesures optiques f i n e s concernant l a t r a n s i t i o n 2 x 1 -* 2 x 8 ont été i n t e r p r é t é e s en f o n c t i o n de l a m o d i f i c a t i o n de l a constante d i é l e c t r i q u e d'une couche de t r a n s i t i o n . Cette v a r i a t i o n , transposée à l a c o n d u c t i v i t é é l e c t r i q u e de s u r f a c e , a été comparée à l a v a r i a t i o n déterminée l o r s de mesures é l e c t r i q u e s s t a - t i q u e s .
Abstract - The el 1 ipsometric method, relatively easy to handle, is very sensitive to any modification and perturbation which may occur on a crystalline surface. In the case of semiconductors (Ge, S i ) , the surface perturbation may have different origins. Typically, temperature effects lead to surface structural modifications (reconstruction) of Ge (111) 2 x 8 (or Si (111) 7 x 7 ) .
We have studied optically the 2 x 1 -> 2 x 8 surface transition of Germanium as a function of temperature (300 K<T<700 K ) .
On the one hand we have shown that the variation with temperature of the Gap ener- gy Eg has strong influence on the surface optical constants of the semiconductors.
The good agreement between the ellipsometric measurements performed as a function of temperature and those obtained elsewhere with variable wavelengths show that the optical transitions give the same energy bands in the temperature domain inves- tigated.
On the other hand fine optical measurements concerning the 2 x 1 - 2 x 8 transition have been interpreted in terms of the modification of the dielectric constant of a transition layer. This variation transposed to surface electrical conductivity has been compared with the variation determined upon static electrical measurements.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19831094
