23 Avenue des M a r t y r s -38031 GRENOBLE -Cedex (France) E.N.S.E.R.G. -L a b o r a t o i r e d ' E l e c t r o n i q u e (ERA CNRS 659) A B S T R A C T The a u t h o r s p r e s e n t a rigorous and complete a n a l y s i s o f t h e w o r k i n g o f MIS ( m e t a li n s u l a t o rs e m i c o n d u c t o r ) s o l a r c e l l s , t h e a d v a n t a g e s o f which a r e now t h e optimum value of which i s determined. The i n t e r f a c e s t a t e s a r e s u p p o s e d i n t e r a c t i n g w i t h f r e e c a r r i e r s o f t h e t h r e e r e s e r v o i r s i . e , metal, semiconductor conduction and valence band. The p r e s e n t e d work a l l o w s u s , f o r t h e first t i m e t o o u r k n o w l e d g e , n o t o n l y t o c h a r a c t e r i z e i n d e t a i l MIS s o l a r c e l l s b u t a l s o t o f o r e s e e t h e f ab r i c a t i o n o f optimum d e v i c e s . I n p r e v i o u s p u b l i c a t i o n s , we h a v e e s t a b l i s h e d a n d d i s c u s s e d t h e b a s i c e q u a t i o n s o f t h e p h o t o v o lt a i c working of the MIS t u n n e l d i o d e C1,2,3,41. I n t h i s p a p e r , we p r e s e n t t h e d e t a i l e d n u m e r ic a l s o l u t i o n s o f t h e s e e q u a t i o n s by p l o t t i n g I ( U ) c h a r a c t e r i s t i c s o f t h e MIS Schottky diode under illumination (AM1) as a f u n c t i o n o f t h e i n t e r f a c e p a r am e t e r s . I n p a r t i c u l a r , we t a k e i n t o a c c o u n t t h e i n f l u e n c e of t h e t h i c k n e s s o f t h e i n s u l a t i n g l a y e r crossed by t u n n e l e f f e c t a n d we p o i n t o u t t h e a c t i o n as much k i n e t i c a s e l e c t r o s t a t i c o f t h e i n t e r f a c e s t a t e s . The r e s u l t s c o n c e r n N type monocrystalline s i l i c o n ( n u m e r i c a l v a l u e s o f v a r i o u s p a r a m e t e r s a r e g i v e n a t t h e e n d o f t h e p a p e r ) . W e s h a l l f i r s t examine t h e w o r k i n g o f t h e i d e a l s t r u c t u r e w i t h o u t i n t e r f a c e s t a t e s . A f t e r w a r d s , t h e s t r u c t u r e w i t h i n t e r f a c e s t at e s will be analysed as a f u n c t i o n o f t h e k i n d o f i n t e r a c t i o n of s t a t e s w i t h t h e t h r e e c a r r i e r s " r e s e rvoirs" (metal, conduction and valence bands of the semiconductor), For sake o f s i m p l i c i t y i n t h e p r es e n t a t i o n o f t h e r e s u l t s , we s h a l l d i s t i n g u i s h two cases : ( i ) i n t e r f a c e s t a t e s i n t e r a c t i n g w i t h one r e s e rv o i r , ( i i ) g e n e r a l c a s e , i . e . i n t e r f a c e s t a t e s i n t e r a ct i n g w i t h t h e t h r e e r e s e r v o i r s . The b a s i c e q u a t i o n s , which can be found in t h e above mentioned works, will n o t b e r e w r i t t e n . IDEAL STRUCTURE (WITHOUT INTERFACE STATES) Figure 1 shows c u r r e n t d e n s i t yvoltage char a c t e r i s t i c s f o r v a r i o u s i n s u l a t o r t h i c k n e s s e s 6 , W e n o t...

An exposure of Schottky diodes on hydrogenated amorphous silicon (a-SiH) for several hours to light (AM1) reduces by a factor of 4 the dark forward current at V=1 V as well as the photocurrent under low illumination. Annealing above 150 °C partly reverses the process. Current-voltage measurements versus temperature show a shift of the bulk Fermi level of about 80 mV from the conduction band due to the increasing of the density of states in the midgap of a-SiH as can be seen from capacitance-voltage measurements. We explain the surprising stability of the photovoltaic functioning by the trapping of photogenerated holes which acts as an optical doping of the material.

This paper summarizes an experimental investigation into the behaviour of high strength sandlightweight concrete columns confined with rectangular ties. Fifteen reinforced and three unreinforced specimens were tested under monotonically increasing axial compression. Variables considered in this study were the longitudinal steel distribution and tie configuration, the tie steel spacing, the amount of tie steel, and the amount of longitudinal steel.The results indicated that unconfined high-strength lightweight aggregate concrete is a brittle material. The addition of lateral confining steel significantly improved the behaviour of this material, with a large amount of lateral steel resulting in very ductile behaviour. The tic configuration and resulting distribution of longitudinal steel contributed significantly to the confinement of concrete, with well-distributed steel resulting in improved bchaviour. The ratio of specimen to cylinder concrete strength was observed to be 0.98, which is much higher than the commonly assumed value of 0.85.The test results were compared with results from selected theoretical confinement models. Based on the results of this investigation, existing models for concrete confinement give unconservative results for high-strength lightweight aggregate concrete and overestimate the ductility that can be achieved with this material.Cette communication resume une Ctude expkrimcntale du comportement dc poteaux de bkton lCgcr h haute rksistancc retenus par des agrafes mktalliques. Quinze kchantillons arrnCs et trois non armCs ont fait I'objet d'cssais sous compression axialc progressivement augmentie. Les variables dont on a tenu compte dans cette Ctude sont la rkpartition longitudinale de I'acicr et la configuration des agrafes, I'espacement de I'acicr des agrafes, la quantite d'acier dans les agrafes et la quantiti d'acier longitudinal.Les rCsultats indiquent que le beton d'agrCgats ICgers h haute rksistance sans Ctreinte laterale est un matkriau fragile. L'addition de supports IatCraux en acier a amCliorC de faqon significative le comportement de ce matkriau, I'importante quantitC d'acier lateral entrainant une trks grande ductilite. La forme des agrafes et la repartition de I'acier longitudinal qui en a rdsultec ont contribuk de faqon significative au confinement du Eton, I'acier bien rkparti favorisant un mcillcur comportement. On a observe que le rapport entre I'Cchantillon et la resistance du bCton cylindrc Ctait de 0,98, cc qui cst beaucoup plus ClcvC quc la valeur de 0,85 gtneralement admise.Les rksultats d'essais ont CtC comparks aux rksultats de ccrtains modkles dc confinement thkoriques. En tcnant compte des rksultats de cette Ctude, les modkles actuels de confinement du beton donnent des rksultats excessifs pour le beton d'agrkgats ICgers A haute resistance et surestiment la ductilitk qu'on peut obtenir avec ce matkriau.

No abstract

No abstract