STABILITY OF POLYACETYLENE DOPED BY ION IMPLANTATION

HAL Id: jpa-00222689

https://hal.archives-ouvertes.fr/jpa-00222689

Submitted on 1 Jan 1983

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

STABILITY OF POLYACETYLENE DOPED BY ION IMPLANTATION

J. Davenas, X. Xu, M. Maitrot, M. Gamoudi, G. Guillaud, J. André, B.

François, C. Mathis

To cite this version:

J. Davenas, X. Xu, M. Maitrot, M. Gamoudi, G. Guillaud, et al.. STABILITY OF POLYACETY- LENE DOPED BY ION IMPLANTATION. Journal de Physique Colloques, 1983, 44 (C3), pp.C3- 183-C3-188. �10.1051/jphyscol:1983337�. �jpa-00222689�

JOURNAL DE PHYSIQUE

Colloque C3, supplément au n°6, Tome 44, juin 1983 page C3-183

S T A B I L I T Y OF POLYACETYLENE DOPED BY ION IMPLANTATION

J. D a v e n a s ^ , X.L. Xu^! ), M. Maitrot^ , M. Gamoudi( \ G. GuillaucT , J.J. André1 S B. François^3' and C. Mathis^3)

(1) Département de Physique des Matériaux, 45 Bld du 11 Novembre, S9622 Villeurbanne Cedex, France

(2) Laboratoire de Physique Electronique, 42 Bld du 11 Novembre, 69622 Villeurbanne Cedex, France

(S) Centre de Recherche sur les Macromolécules, 6 Rue Boussingault, 6708S Strasbourg Cedex, France

Résumé - L'introduction d'impuretés dopantes dans des polymères tels que (CH) permet d'induire des'propriétés semiconductrices de type p ou n, ou même un régime de conduction métallique lorsque l'on augmente la concentration. Nous présentons de nouveaux résultats concernant la stabilité du polyacétylène dopé par implantation d'ions, vis à vis: (1) de la dégradation induite par l'irra- diation ionique (2) de l'oxydation et (3) des traitements thermiques. Deux types de techniques ont été utilisées dans ce but: (1) la modification des propriétés électriques et (2) la microanalyse nucléaire pour la détermination du profil de distribution des différents éléments chimiques. En particulier, la résonance à 6385 keV de l'azote 15 a été utilisée pour déterminer la compo- sition en hydrogène de la matrice en fonction de la profondeur. La répartition des différentes espèces dopantes et son évolution au cours des traitements a été étudiée par rêtrodiffusion Rutherford.

Abstract - The introduction of doping impurities in polymers such as (CH) can induce n or p type semiconducting p r o p e r t i e s or a m e t a l l i c regime when i n - creasing the concentration. We present some new r e s u l t s on the s t a b i l i t y of (CH) films doped by ion implantation, in respect t o : (1) the degradation i n - duced" by the ionic i r r a d i a t i o n , (2) oxidation, (3) thermal annealings. For t h a t purpose two types of techniques have been used (1) modification of the e l e c t r i c a l conductivity and (2) nuclear microanalysis for depth p r o f i l i n g of the d i f f e r e n t elements. In p a r t i c u l a r the nuclear resonance a t 6385 keV of N was used to determine the hydrogen composition of the matrix as a function of the depth. The r e p a r t i t i o n of the d i f f e r e n t doping species and the evolution with annealings was studied by Rutherford Backscattering Spectroscopy (RBS).

I - INTRODUCTION

The i n t e r e s t o f i o n i m p l a n t a t i o n f o r t h e s y n t h e s i s o f new m a t e r i a l s h a s b e e n d e m o n s t r a t e d d u r i n g t h e s e l a s t y e a r s by t h e number o f p a p e r s d e v o t e d t o t h i s t o p i c . The m a j o r a d v a n t a g e o f t h i s t e c h n i q u e i s t h e p o s s i b i l i t y o f d o p i n g a m a t e r i a l w i t h any i m p u r i t y i r r e s p e c t i v e l y o f d i f f u s i o n l a w s and a c c u r a t e a d j u s t e m e n t o f t h e l o c a l c o m p o s i t i o n . However t h e p r i m a r y e f f e c t s o f i m p l a n t a t i o n a r e o f t e n f o l l o w e d by b a c k r e a c t i o n s and m a t e r i a l s s y n t h e t i z e d by t h i s t e c h n i q u e a r e g e n e r a l l y i n a m e t a s t a b l e e q u i l i b r i u m . F o r t h a t r e a s o n s t a b i l i t y i s a f u n d a m e n t a l p r o b l e m i n i m p l a n t a t i o n . I o n i m p l a n t a t i o n a p p e a r e d i n t h e l a s t d e c a d e s a s a p o w e r f u l l t e c h n i q u e f o r t h e d o p i n g o f m i n e r a l s e m i c o n d u c t o r s and was t e s t e d r e c e n t l y a s a new m e t h o d / 1 , 2 , 3 , 4 / of d o p i n g i n t h e c a s e o f s e m i c o n d u c t i n g p o l y m e r s . Among t h e s e p o l y m e r s , p o l y a c e t y l e n e h a s b e e n e x t e n s i v e l y s t u d i e d b e c a u s e i t was t h e f i r s t t o be s y n t h e t i z e d i n a p r o c e s s a b l e form and b e c a u s e i t can be e a s i l y doped by c h e m i c a l m e a n s . The low r e d o x p o t e n t i a l of p o l y a c e t y - l e n e a c c o u n t s f o r t h e e a s i n e s s o f (CH) d o p i n g w h i c h may b e a p r o b l e m b e c a u s e o f t h e d i f f i c u l t y t o a v o i d d o p i n g by i m p u r i t i e s , i n p a r t i c u l a r o f t h e c a t a l y s e r u s e d i n i t s s y n t h e s i s and by t h e o x y g e n of t h e a i r . From t h a t p o i n t o f v i e w , i o n i m p l a n t a t i o n may a p p e a r a s a c l e a n p r o c e d u r e o f d o p i n g , b u t h a s t h e d i s a d v a n t a g e o f p r o d u c i n g d e f e c t s w h i c h may i n d u c e a d e g r a d a t i o n o f t h e m a t e r i a l . The l a s t p r o b l e m i s t h e t h e r m a l s t a b i l i t y

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983337

C3-184 JOURNAL DE PHYSIQUE

of t h e doping s p e c i e s which must s t a y r e a s o n a b l e f o r t e m p e r a t u r e s r a n g i n g 100° C s i n c e t h i s i s t h e domain o f o p e r a t i n g t e m p e r a t u r e s which may be met i n e l e c t r o n i c d e v i c e s . We have t h e n c o n s i d e r e d t h e t h r e e f o l l o w i n g a s p e c t s : ( 1 ) s t a b i l i t y o f p o l y a c e t y l e n e towards i o n i c i r r a d i a t i o n

( 2 ) s t a b i l i t y o f implanted ( C H ) i n r e s p e c t t o o x i d a t i o n ( 3 ) t h e r m i c s t a b i l i t y o f t h e imfilant

I1 - EXPERIMENTAL

The ( C H f i l m s were grown a t t h e CRM S t r a s b o u r g (CNRS) i n t h e u s u a l way / 5 / ) 8 n a Z i e g l e r - N a t t a l a y e r o f c a t a l y s t s o l u t i o n / 6 / . The p u r i t y o f i n t r i n s i c p o l y a c e t y l e n e h a s been c h a r a c t e r i z e d by d u t h e r f o r d Back- s c a t t e r i n g Spectroscopy a t t h e Dgpartement de Physique d e s Matkriaux and t h e e l e c t r i c a l c o n d u c t i v i t y , which was s t u d i e d a t t h e L a b o r a t o i r e de Physique E l e c t r o n i q u e , showed a c l o s e c o n n e c t i o n between t h e measured v a l u e s and t h e c o n c e n t r a t i o n o f r e s i d u a l i m p u r i t i e s remaining from t h e c a t a l y s i s 171. Improvment of t h e p r e p a r a t i o n procedure ( s l o w procepfbng and s e v e r a l washings) l e a d e d t o low s u r f a c e c o n d u c t i v i t i e s ( a d 10 Rcm) f o r samples e x h i b i t i n g no d e t e c t a b l e t r a c e s of c a t a l y s e r i n t h e v i c i n i t y o f t h e s u r f a c e . P o l y a c e t y l e n e h a s been c o m p l e t e l y i s o m e r i z e d i n t o t r a n s - p o l y a c e t y l e n e by a thermal t r e a t m e n t a t 150° C d u r i n g a b o u t 1 5 min.

The p o l y a c e t y l e n e f i l m s were implanted a t l i q u i d n i t r o g e n t e m p e r a t u r e i n o r d e r t o l i m i t t h e r a t e o f d e f e c t c r e a t i o n . Two e l e c t r o d e s were eva- p o r a t e d a f t e r i m p l a n t a t i o n on t h e i r r a d i a t e d s u r f a c e o f t h e f i l m f o r c o n d u c t i v i t y measurements. The measure o f t h e c o n d u c t i v i t y o f t h e implan- t e d l a y e r , which i s d i f f i c u l t because o f i t s t h i n and b u r i e d n a t u r e , was p o s s i b l e because o f t h e d i f f u s i o n o f t h e e v a p o r a t e d e l e c t r o d e s i n t h e f i l m which was demonstrated by RBS. T h i s d i f f u s i o n allowed a good c o n t a c t between t h e e l e c t r o d e s and t h e doped l a y e r .

A n u c l e a r r e a c t i o n was used i n o r d e r t o d e t e r m i n e t h e hydrogen p r o f i l e . The m i c r o a n a l y s i s was done a t t h e I n s t i t u t de Physique N u c l k a i r e de Lyon w i t h t h e h e l p o f a beam of doubly charged n i t r o g e n i o n s produced i n a 4 MeV Van de G r a a f .

I11 - STABILITY TOWARDS I O N I C I R R A D I A T I O N

During t h e i m p l a n t a t i o n t h e a c c e l e r a t e d p a r t i c l e s l o o s e t h e i r k i n e t i c e n e r g y i n t h e t a r g e t a c c o r d i n g t o v a r i o u s mechanisms which a r e respon- s i b l e of t h e d e f e c t c r e a t i o n . The e n e r g y exchanges depend upon t h e masses and r e l a t i v e e n e r g i e s o f i n c i d e n t and t a r g e t p a r t i c l e s and may be c o n s i d e r e d a r e q u i t e s i m i l a r f o r two s u c c e s s i v e e l e m e n t s i n t h e p e r i o d i c a l t a b l e . Then same r a t e s o f d e f e c t c r e a t i o n a r e t o be e x p e c t e d f o r i m p l a n t a t i o n s , w i t h c h l o r i n e and argon i o n s a t t h e same e n e r g y , and d i f f e r e n c e s i n t h e p r o p e r t i e s o f two samples implanted i n such c o n d i t i o n s must be a t t r i b u t e d t o t h e n a t u r e o f t h e implanted chemical s p e c i e s . F i g u r s 1 phows t h e c u r r e n t - v o l t a g e c u r v e s of two samples i m p l a n t e d w i t h 3 . 1 0 C 1 and I- i o n s a t 50 keV on a l o g - l o g s c a l e . We o b s e r v e two main p r o p e r t i e s :

- a m o d i f i c a t i o n o f t h e c o n t a c t p r o p e r t i e s which become ohmic and which may be connected t o t h e i r r a d i a t i o n i t s e l f

- d i f f e r e n t e l e c t r i c a l a c t i v i t i e s o f t h e two implanted s p e c i e s showing e v i d e n c e f o r a doping e f f e c t o f c h l o r i n e i o n s

However polymers a r e r e p u t e d t o be v e r y s e n s i t i v e t o i r r a d i a t i o n s and a d e g r a d a t i o n o f t h e m a t e r i a l h a s been shown t o o c c u r , i n some c a s e s w i t h a complete c a r b o n i z a t i o n o f t h e samples / 9 / . A s example o f an a p p l i - c a t i o n o f such an e f f e c t , i o n beams have been used a s t h e i n c i d e n t r a d i a - t i o n i n l i t h o g r a p h y f o r t h e e t c h i n g o f q e s i s t s / l o / . I n o r d e r t o e v a l u a t e t h e maximum damage which may be met i n such i r r a d i a t i o n s , we h a v f 7 d e t e r - mined t h ~ hydrogen composition o f a ( C H ) f i l m implanted w i t h 1 0 A r i o n s / cm a t 50 keV. The l o c a l c o n c e n t r a f i o n o f Argon atoms i s t h e n of

t h e l s r d e r o f 2 0 % . For t h a t purpose we u s e d t h e resonance a t 6 3 8 5 keV o f N on t a r g e t hydrogen a c c o r d i n g t o t h e n u c l e a r r e a c t i o n :

1 5 + ~'H -t 12c + a + ^y

By v a r y i n g t h e i n c i d e n t energy o f t h e n i t r o g e n beam i t i s t h e n p o s s i b l e t o s h i f t t h e resonance d e e p e r i n s i d e t h e sample and t h e v a r i a t i o n o f t h e i n t e n s i t y o f t h e e m i t t e d y s i g n a l a l l o w s t h e r e c o n s t r u c t i o n of t h e hydrogen p r o f i l e . A non i r r a d i a t e d sample i s used a s r e f e r e n c e . The p r o f i l e p r e s e n t e d i n f i g u r e 3 shows t h a t a l l t h e i r r a d i a t e d t h i c k - n e s s h a s been s e v e r e l y damaged s i n c e t h e hydrogen d e f i c i t i s l a r g e r t h a n 5 0 % . I n t h e i m p l a n t a t i o n t h i c k n e s s t h e hydrogen c o n c e n t r a t i o n i s reduced o f about one h a l f . Another s u r p r i s i n g f a c t i s t h e e x t e n t o f t h e d e f i c i t zone which i s 10 t i m e s l a r g e r t h a n t h e i o n range and which i s n o t c o n s i s - t e n t w i t h t h e assumption o f an e q u a l d e p t h used by t h e Motorola Group i n t h e s t u d y o f t h e d e g r a d a t i o n o f v a r i o u s o r g a n i c r e s i s t s by t h e measurt o f t h e g a s o u t g a s s i n g from t h e sample /lo/.

IV - O X I D A T I O N O F IMPLANTED POLYACETYLENE

The o x i d a t i o n o f two samples, a r e f e r e n c e and a ~ p p l e . o r i g i n a t i n g ₂ i n t h e same f i l m which h a s been i m p l a n t e d w i t h 5.10 i o d l n e i o n s / cm a t 1 0 0 keV, w a s s t u d i e d by R u t h e r f o r d B a c k s c a t t e r i n g S p e c t r o s c o p y . I n t h i s t e c h n i q u e , a beam o f l i g h t p a r t i c l e s a c c e l e r a t e d a t some MeV i s u s e d a s a probe t o determine t h e d i s t r i b u t i o n o f heavy atoms i n a l i g h t m a t r i x . From t h e energy d i s t r i b u t i o n o f t h e e l a s t i c a l l y s c a t t e r e d p a r t i c l e s i t i s p o s s i b l e t o deduce t h e p r o f i l e o f t h e i m p u r i t i e s such a s t h e implan- t e d i o n s o r t h e oxygen due t o t h e sample c o n t a m i n a t i o n a f t e r exposure t o t h e a i r . I n t a b l e 1 we have g a t h e r e d t h e oxygen c o n c e n t r a t i o n s (oxygen t o m a t r i x c a r b o n r a t i o ) a s a f u n c t i o n o f t h e t o t a l time o f exposure t o t h e a i r f o r an implanted and a p r y s t i n e sample. These con- c e n t r a t i o n s h a v e b e e n c a l c u l a t e d by t h e i n t e g r a t i o n o f t h e t o t a l number o f oxygen atoms and i t s r a t i o t o t h e c o r r e s p o n d i n g number of c a r b o n atoms t a k e n i n t o two d i f f e r e n t zones:

- one r e f e r r e d a s t h e s u r f a c e , c o r r e s p o n d i n g t o t h e i r r o a d i a t e d l a y e r , t h e t h i c k n e s s of whicQ h a s been chosen e q u a l t o 4000 A (mean range o f i m p l a a t e d i o n s : 3 0 0 0 A , h a l f w i d t h o f t h e d i s t r i b u t i o n o f doping i o n s : 1 0 0 0 A ) .

- t h e o t h e r a s t h e volume, which must m o s t l y r e f l e c t t h e e r o p e r t i e s of t h e b u l k , t h e w i d t h o f which h a s been l i m i t e d t o 1 5 0 0 0 A.

-

I n c l d e n t beam 15N

D e t e c t o r

.I

1 1 0 l 0 0 V 6 ⁰ ;o 0 :o 0 0 $0 &cm2

Figure 1: current-voltage curves of 6.3 6 . 5 7 7.5 8 MeV

(CH) samples: ( I ) pristine, (2) im-

planred with 3.1 015 C1 /cm2 at 50 keV Figure 2: hydrogen profile of a (CH)x (3) implanted with 3. loi5 I-/cm2 at sample:( A) pristine, (.) implanted

100 keV. with 10" ~r~on/cm' at 50 keV.

JOURNAL DE PHYSIQUE

I I I I I I

Table 1: comparison between the oxidation rates of an implanted and pristine (CH)x sample versus time of exposition to air

I I IMPLANTED (CH)X INON-IMPLANTED (CH) I

I

I I

I I I surface1 volume I

Two main properties may be deduced from these results:

- polyacetylene doped by implantation with iodine is less sensitive to the oxidation of the air than the undoped sample. The reduction of sensitivity to the oxygen is however small and this observation is con- tradictory with the results of Weber et al. /11/ based on conductivity measurements.

- two stages may be distinguished: a fast oxidation stage and a saturation state reached after 4 hours exposure to the air.

The change of the oxidation rate corresponds to a redistribution of the oxygen which is initially purely superficial and diffuses into the bulk during the second stage. Bulk oxidation becomes larger than the surface oxidation in this stage.

The conductivity of these two samples has also been studied according to the exposure time to the air. Figure 3 clearly shows the two stages revealed by the RBS. We also find the lower rate of saturation of the implanted sample. However an inversion of the relative conductivities of the two samples may be observed in the very initial stage. In fact the larger conductivity of the implanted sample at the origin corresponds to a larger oxidation state in RBS. A possible explanation is that the irradiation produces a large number of dangling bonds by a radiolysis mechanism, which are saturated very quickly by the residual oxygen pre-

sent in the vacuum system or during the transfer in the various measure cells.

I

1 0 - ~

I

.

^I

Figure 3: Evolution of the conductance with exposure time tp6air of 2 (CH)x samples: ( Q ) pristine, ( A ) implanted with 5.10 I /cm 2

I

V - THERMAL STABILITY OF IMPLANTED POLYACETYLENE

We compared t h e s t a b i l i t y o f v a r i o u s doping s p e c i e s : I o d i n e , c h l o r i n e and Fe i o n s implanted t o g e t h e r i n a f i l m o f t r a n s p o l y a c e t y l e n e . For t h a t purpose t h e implanted sample was h e a t e d a t Z O O o C i n t h e a n a l y z i n g chamber and t h e RBS spectrum was r e c o r d e d a t d i f f e r e n t a n n e a l i n g t i m e s ( s e e f i g u r e 4 ) . The t o t a l number o f t h e d i f f e r e n t chemical s p e c i e s was deduced from t h e i n t e g r a t e d a r e a s of t h e d i f f e r e n t p e a k s and p l o t t e d v e r s u s time i n f i g u r e 5. T h i s f i g u r e shows t h a t t h e s t a b i l i t y remains remarkable f o r t i m e s o f t h e o r d e r of 1 0 h o u r s whereas t h e dopant concen- t r a t i o n had a l r e a d y been reduced by more t h a n a f a c t o r 2 d u r i n g t h i s time i n p o l y a c e t y l e n e c h e m i c a l l y doped w i t h i o d i n e / 1 2 / . However t h e comparison w i t h t h e dopant d e s o r p t i o n k i n e t i c s o f t h e M o n t p e l l i e r Group shows t h a t t h e mechanism i s more c o m p l i c a t e d i n implanted samples what i s q u i t e u n d e r s t a n d a b l e s i n c e i m p l a n t a t i o n i s b a s i c a l l y a b u l k doping p r o c e s s i n v o l v i n g two p r o c e s s e s f o r d e s o r p t i o n : d i f f u s i o n from t h e b u l k t o t h e s u r f a c e o f f i b r i l s and t h e n d e s o r p t i o n from t h e f i b r i l s u r f a c e .

..-.*

... 721 min 2 MeV

00 959 min a t 100' C 4 ~ e + ;e+y

3

d e t e c t o r

E = E - E '

-

9 . 0 x

u p = ( S I X

epu . C lq&

;

Icl ,IFe ,I'

0 *.

'?

d%ew;d G Q , ~ o a i a . B w 6 ~

channel number -+

T

- - - ^{-Fe I}

I- 1015!y2!

3 ---C1

-

. '

- 2

1 -

'0..

o,-o-, -

0 . 2 ^{I I} I I 4 , 0 . 7

0 100 200 300 400 500 600 700 800 900 1000 time (min.)-

F i g u r e s 4 and 5: RBS spectrum and e v o l u t i o n o f t h e number o f t h e d i f f e r e n t i m p l a n t e d s p e c i e s v e r s u s a n n e a l i n g time a t 100° C

JOURNAL DE PHYSIQUE

V I - CONCLUSION

N u c l e a r m i c r o a n a l y s i s f o r h e a v i e r e l e m e n t s )

t e c h n i q u e s ( n u c l e a r r e a c t i o n s f o r hydrogen and RBS have a l l o w e d t h e c h a r a c t e r i z a t i o n o f i m p l a n t e d p o l y a c e t y l e n e f i l m s and t h e s t u d y of t h e i r s t a b i l i t y . T h e c o m b i n a t i o n o f t h e s e techniques w i t h e l e c t r i c a l c o n d u c t i v i t y m e a s u r e m e n t s c l e a r l y s h o w s t h a t t w o c o m p e t i t i n g processes are i n v o l v e d i n t h e i m p l a n t a t i o n p r o c e s s : m a t e r i a l degradation a n d c h e m i c a l doping. F r o m t h e p o i n t o f v i e w o f e l e c t r i c a l p r o p e r t i e s t h e doping e f f e c t i s d o m i n a t i n g , b u t t h e r a t e o f d a m a g e m a y be severe f o r l a r g e f l e n c e s and should p r o b a b l y be a l i m i t i n g f a c t o r of t h e e l e c t r i c a l a c t i v i t y . H o w e v e r t h e i m p r o v e d resis- tance t o o x i d a t i o n and t h e t h e r m a l s t a b i l i t y a r e very i n t e r e s t i n g r e s u l t s . T h e f i r s t s h o w s t h a t the n u m b e r of dangling bonds c r e a t e d by t h e r a d i o - l y s i s r e m a i n s l i m i t e d w h e r e a s t h e second i n d i c a t e s t h a t t h e s t a b i l i t y o f t h e dopant s t a y s a c c e p t a b l e f o r o r d i n a r y o p e r a t i n g t e m p e r a t u r e s o f e l e c t r o n i c d e v i c e s . A l a s t r e m a r k i s t h a t F e appears t o b e a v e r y s t a b l e and e l e c t r i c a l l y a c t i v e s p e c i e i n i m p l a n t e d s p e c i m e n s .

ACKNOWLEDGMENTS

I t i s a p l e a s u r e t o a c k n o w l e d g e D r . J P . THOMAS f r o m t h e I n s t i t u t e o f P h y s i q u e N u c l e a i r e de L y o n f o r p e r f o r m i n g t h e hydrogen p r o f i l i n g e x p e r i m e n t and f o r h e l p f u l d i s c u s s i o n s .

REFERENCES

1 - ^WN. ALLEN, P . BRANT, CA. CAROSELLA, J J . de CORPO, C T . EWING, F E . SAALFELD a n d D C . WEBER S y n t h e t i c M e t a l s , 1 ( 1 9 7 9 / 8 0 ) 151 2 - J S . ABEL, H . MAZUREK, DR. DAY, EW. MABY, S D . S E N T U R I A , G. and MS.

DRESSELHAUS M e t a s t a b l e M a t e r i a l s F o r m a t i o n by Ion I m p l a n t a t i o n E l s e v i e r S c i e n c e P u b l i s h i n g C o , I n c ( 1 9 8 2 ) S T . P i c r a y x and WJ. C h o y k e E d i t o r s

3 - J . DAVENAS,C. DUPUY, XU X I N G LONG, M. MAITROT, J J . ANDRE e t B. FRANCOIS LATDIC C o n f e r e n c e D u b l i n ( 1 9 8 2 ) t o be p u b l . i n R a d . E f f e c t s

4 - H. MAZUREK, DR. DAY, EW. MABY, J S . A B E L , S D . S E N T U R I A , G. and MS.

DRESSELHAUS IBMM C o n f e r e n c e G r e n o b l e ( 1 9 8 2 ) t o be p u b l . i n N u c l . I n s t . and M e t h o d s

5 - H. SHIRAKAWA, S . I K E D A , P o l y m . J . 2 ( 1 9 7 1 ) 3

T . I T O , H. SHIRAKAWA, S . IKEDA, J . P o l y m . S c i . L e t t . , P o l y m . C h e m . E d . 1 2 ( 1 9 7 4 ) 11

6 - B. F R A N C O I S , M. BERNARD and J J . ANDRE J . C h e m . P h y s . 75 ( 1 9 8 1 ) 4 1 4 2 7 - M. GAMOUDI, J J . ANDRE, B . FRANCOIS and M. MAITROT J . de P h y s i q u e

43 ( 1 9 8 2 ) 953

8 - J P . THOMAS, C . P I J O L A S e t M. FALLAVIER R e v u e de P h y s i q u e A p p l i q u k e 13 ( 1 9 7 8 ) 433

9 - T . VENKATESAN, S R . FORREST, ML. KAPLAN, P H . SCHMIDT, A.LOVINGER CA. MURRAY, R. ROBERTS and H. SCHONHORN IBMM C o n f e r e n c e G r e n o b l e

( 1 9 8 2 ) t o be p u b l . i n N u c l . I n s t . and M e t h o d s

1 0 - I L E S A N M I A D E S I D A IBMM C o n f e r e n c e G r e n o b l e ( 1 9 8 2 ) t o be p u b l . i n N u c l . I n s t . and M e t h o d s

TC. S M I T H I n t . C o n f . I o n I m p l a n t a t i o n ( E q u i p m e n t and T e c h n i q u e s ) B e r c h t e s g a d e n ( 1 9 8 2 ) t o be p u b l . by S p r i n g e r V e r l a g

11 - DC. WEBER, P. BRANT and CA. CAROSELLA M e t a s t a b l e M a t e r i a l s F o r m a t i o n by Ion I m p l a n t a t i o n E l s e v i e r P u b l i s h i n g Co, I n c ( 1 9 8 2 ) S T . P i c r a u x and W J . C h o y k e E d i t o r s

1 2 - M . ROLLAND, S . LEFRANT, M. A L D I S S I , P . B E R N I E R , E . RZEPKA and F. SCHUE J . o f E l e c t r o n i c M a t e r i a l s 10 ( 1 9 8 1 ) 4