HAL Id: jpa-00219049
https://hal.archives-ouvertes.fr/jpa-00219049
Submitted on 1 Jan 1979
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.
MOTION OF CHARGED DISLOCATIONS IN SEMICONDUCTORS AII BVI
Yu. Ossipyan, V. Petrenko
To cite this version:
Yu. Ossipyan, V. Petrenko. MOTION OF CHARGED DISLOCATIONS IN SEMICON- DUCTORS AII BVI. Journal de Physique Colloques, 1979, 40 (C6), pp.C6-161-C6-167.
�10.1051/jphyscol:1979633�. �jpa-00219049�
JOURmAL DE PHYSIQUE ColZoque C6, suppl6ment au n06, t o n e 40, j u i n 1979, page C6-161
MOTIO,\I OF CHAiiGED DISLOCATIONS I N SEMI CONDUCTORS An B=
Yu. A. Ossipyan and V.F. Pctrenko
S o l i d S t a t e Physics I n s t i t u t e USSR Academy o f S c i e n c e s , 142432 Chemogolovka, U.S. S. R.
Resume.- De nouveaux phenomPnes l i e s au mouvement de d i s l o c a t i o n s chargees pendant l a deformation de c r i s t a u x 0 n o n t e t e mis en evidence ( e f f e t de c o u r t c i r c u i t , courant dir aux d i s l o c a t i o n s , e f f e t s e l e c t r o p l a s t i q u e s " c r o i s e s " ) . L ' e f f e t photoplastique e t l a luminescence due ii l a deformation sont d i s - c u t & en termes de v a r i a t i o n s de l a charge des d i s l o c a t i o n s . I 1 en r e s u l t e que l e s parametres d ' a c t i - v a t i o n du mouvement desdislocationsd@pendent fortement de l e u r @ t a t de charge.
Abstract.- New phenomena connected w i t h movement o f t h e charqed d i s l o c a t i o n s d u r i n g t h e p l a s t i c d e f o r - mation o f m ~m c r y s t a l s have been observed e x p e r i m e n t a l l y ( s h o r t - c i r c u i t i n g e f f e c t , d i s l o c a t i o n c u r r e n t , odd e l e c t r o ~ l a s t i c e f f e c t ) . The p h o t o p l a s t i c e f f e c t and deformation luminescence a r e discussed i n terms o f t h e d i s l o c a t i o n charge v a r i a t i o n . A c t i v a t i o n parameters o f a d i s l o c a t i o n movement t u r n o u t t o be s t r o n g l y dependent on t h e d i s l o c a t i o n l i n e charge.
1. I n t r o d u c t i o n . - At present two groups o f c r y s t a l s qi and moving w i t h d i f f e r e n t v e l o c i t i e s qid a r e i n v o l - are known i n which researchers succeeded i n measuring ved i n t h e deformation. The d i s l o c a t i o n c u r r e n t den- d i s l o c a t i o n charges by d i r e c t experimental methods. s i t y i s
I n t h e former. i n t h e a l k a l i = h a l i d e c r y s t a l s (AHC) +
t h e appearance o f c u r r e n t charge on surface a t olas- 'd = li q i n i v i d (1)
t i c deformation was discovered i n as e a r l y as 1933 where ni - t h e i - t y p e d i s l o c a t i o n d e n s i t y and t h e by Stepanov !I/. Since then extensive s t u d i e s of t h e summation i s performed w i t h a l l tyoes o f moving d i s - d i s l o c a t i o n s charges c a r r i e d o u t i n AHC have a1 lowed l o c a t i o n s . The e l e c t r i c a l c u r r e n t s o c c u r r i n g i n t h e t h e i r n a t u r e (charged jogs and k i n k s ) t o be defined r e g i o n o f p l a s t i c deformation and being p r o p o r t i o n a l and have been described i n d e t a i l i n t h e W h i t w i r t h ' s t o i t s r a t e Gn a r e a c t u a l l y observed i n a l l B=
p e r f e c t review /2/. D i s l o c a t i o n charges i n @ a* h i g h - r e s i s t a n c e compounds (ZnS, ZnSe, ZnO, CdS, CdSe, semiconductors have been r e g i s t e r e d f a i r l y r e c e n t l y CdTe). F i g u r e 1 shows t h e scheme o f r e c o r d i n g t h e /3,4/. However, i t has become e v i d e n t immediately d i s l o c a t i o n c u r r e n t s Id; f i g u r e 2 i l l u s t r a t e s an ex- t h a t they a r e a b l e t o p l a y a s i g n i f i c a n t r o l e i n a l l ample o f t h e i r o b s e r v a t i o n i n ZnS /3/.
t h e phenomena r e l a t e d t o p l a s t i c deformation o f these semiconductors : p h o t o p l a s t i c e f f e c t /5,6/, e l e c t r o - p l a s t i c e f f e c t /3,7,8/, s h o r t c i r c u i t e f f e c t a t p l a s - t i c deformation /3/, deformation luminescence /9-111, i o n i z a t i o n o f t r a p l e v e l s a t t h e d i s l o c a t i o n charge motion /12/. An i m p o r t a n t r o l e of e l e c t r i c a l charge of d i s l o c a t i o n s i n t h e phenomena mentioned above i s : 0C8'q' 1) due t o i t s l a r g e value (up t o u n i t e l e c t r o n charge p e r an i n t e r a t o m i c distance); 2) due t o t h e c a p a c i t y o f the d i s l o c a t i o n charge t o change i t s value under t h e e f f e c t o f i l l u m i n a t i o n , temperature, i n j e c t i o n c a r r i e r s e t c .
2. Transport o f charge b&islocations.- 2 . 1 D j s l o c a - tjgn-currg_n_t_s.- Since t h e p l a s t i c deformation of crys- t a l s i s t h e movement o f d i s l o c a t i o n s , i f t h e d i s l o - c a t i o n s a r e charged, t h e e l e c t r i c a l c u r r e n t s accom- panying t h e p l a s t i c deformation occur i n the c r y s t a l volume / 3 / . I n general d i s l o c a t i o n s o f various types w i t h d i f f e r e n t l i n e a r d e n s i t i e s o f e l e c t r i c a l charge
F i g . 1 -
Logarithmic amplif ler
, 1 : Scheme of d i s l o c a t i o n c u r r e n t measuring /19/
q u a r t z punch, 2 - sample w i t h e l e c t r i c a l contacts, t e n s i o n meter, 4 - a m p l i f i e r , 5 - electrometer, 1 o g a r i thmi c amp1 if i e r , 7 - two pens r e c o r d e r , X-Y recorder.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979633
C 6 - 162 JOUKNAI. 1)E I'HY SIQUI:
' min
F i g . ' 2 : S t r e s s - s t r a i n diagram (upper c u r v e ) and d i s - l o c a t i o n c u r r e n t ( I ) i n ZnSe. The d e f o r m a t i o n r a t e s a r e i n d i c a t e d b y needles (u/min) /3/.
However t h e c o r r e l a t i o n between t h e d i s l o c a t i o n c u r - r e n t magnitude and charge d e n s i t y q i t s e l f i s n o t enough t o determine t h i s d e n s i t y because t h e formula ( 1 ) i n v o l v e s n . and Vid + which a r e u s u a l l y unknown.
The procedurebecomeseasier as t h e e x p r e s s i o n f o r 1
t h e p l a s t i c d e f o r m a t i o n r a t e l n = L has a l s o a d i s - l o c a t i o n f l o w n . v . ; 1
1 1
where bi - t h e Burgers v e c t o r , I#Ii - t h e o r i e n t a t i o n f a c t o r . I n p r a c t i c e v e r y o f t e n e x p r e s s i o n Id/ kn can be s i m p l i f i e d . F o r t h e s i m p l i e s t case f o r t h e m o t i o n o f one t y p e o f t h e d i s l o c a t i o n s which a r e p a r a l l e l t o t h e c o n t a c t s one f i n d s
where bz - t h e p r o j e c t i o n o f t h e Burgers v e c t o r on t h e compression a x i s , d - t h e sample w i d t h . I n case o f t h e movement o f t h e o n l y t y p e o f 60' (a- o r 8 - ) d i s l o c a t i o n s and screw d i s l o c a t i o n s i n (0001) p l a n e s o f w u r t c i t e o r (111) o f s p h a l e r i t e
/13/ and e l c .
Thus, t h e v a l u e o f t h e d i s l o c a t i o n l i n e a r charge q can be determined b y f o r m u l a e l i k e ( 3 ) , ( 4 ) f r o m mea- surements o f t h e Id d i s l o c a t i o n c u r r e n t magnitude and d e f i n i n g In by t h e d e f o r m a t i o n diagram. The t e c h n i - que d e s c r i b e d p e r m i t s q t o be d e f i n e d i n t h e case t h e m o b i l i t y o f one t y p e charged d i s l o c a t i o n s i s o n l y much h i g h e r t h a n t h a t o f a l l t h e o t h e r charged d i s l o c a t i o n s . T h i s method was used t o d e f i n e q o f 60" 6 - d i s l o c a t i o n s i n CdS /13/, CdSe and a - d i s l o c a - t i o n s ZnSe /14/. However, t h e method does n o t a l l o w t h e measure q i n case OF simultaneous m o t i o n o f se- v e r a l t y p e s o f charged d i s l o c a t i o n s . One can mention so& o t h e r reasons w h i c h r e s t r i c t o f t h i s t e c h n i q u e use /15/. F o r t h e d i s l o c a t i o n c u r r e n t Id t o be equal t o t h e c u r r e n t i n measuring c i r c u i t i t i s necessary :
Rbx << Ro6. Otherwise, Id = 1 ( 1 + Rbx/Ro6)
h e r e Rbx - t h e i n o u t r e s i s t a n c e o f t h e measuring i n s - trument, Ro6 - o f t h e sample. I n a d d i t i o n , i t i s ne- cessary t h a t t h e s c r e e n i n g r a d i u s Rak s h o u l d be l a r g e r t h a h t h e d i s t a n c e between t h e charged d i s l o c a t i o n s . Otherwise, n e u t r a l o b j e c t s (charged d i s l o c a t i o n s +
s c r e e n i n g charge) move i n t h e sample and t h e d i s l o c a - t i o n c u r r e n t does n o t occur.
2.2. Thq-yot jo~-of-djslo_ca_~fofi-bafld_s. - I t i s known t h a t i n case o f homogeneous e l a s t i c s t r e s s e s d i s l o c a - t i o n s o f d i f f e r e n t types move i n d i f f e r e n t d i r e c t i o n s . I n f a c t , t h e 60" a- and B- d i s l o c a t i o n s move, i n op- p o s i t e d i r e c t i o n s i n p o l a r A= B= c r y s t a l s . These v e r y c o n s i d e r a t i o n s a r e t h e background o f t h e s ~ e t h o d i l l u s t r a t e d i n f i g u r e 3.
Electrometer
i 3
! ' ~ i n ~ . m : l . ' i n d e n t c r
HQ . Jn I I.isuid c o n t a c t '
6
F i g . 3 : a) I l l u s t r a t i o n of d i s l o c a t i o n bands method.
o - s t r e s s s : b ) G l i d e - p l a n e (0001) o f sample w i t h e x t e n d i n g d i s l o c a t i o n l o o p /13/.
D i s l o c a t i o n sources o n t h e sample surfaces a r e p r o - duced by i n d e n t i n g o r s c r a t c h i n g t h e surfaces. The h i g h d i s l o c a t i o n d e n s i t y l a y e r i s removed b y chemi- c a l p o l i s h i n g . The change o f t h e sample l e n g t h ( A l ) and t h e charge v a l u e (LQ) a r e r e g i s t e r e d when t h e d i s l o c a t i o n band has passed ( F i g . 4 ) .
and f o r t h e geometry o f f i g u r e 3 one has const. = 2 b
-.-A . T h i s method has been used t o determine q i n d
CdS f o r d i f f e r e n t d i s l o c a t i o n s : a,B and screw a t (0001) piane, and edge and screw d i s l o c a t i o n s a t (1070) o l ane.
2.3. Ihe-gffect-of-tpe-e1g~trj~-f1e3_d~.- The f o r c e a c t i n g on t h e u n i t l e n g t h o f t h e charged d i s l o c a t i o n i s :
Yu. A . Ossipyan and V.F. P c t r e n k o C6- 163
t i o n c u r r e n t i s due t o d r a g g i n g o f t h e c o n d u c t i o n
L
As can be seen f r o m t r r b l e I t h e charge o f a l l t h e oar
O5
10
is
F i g . 4 : Time diagram o f AQ and A1 d u r i n g a- and d i s l o c a t i o n s i s n e g a t i v e , t h o s e o n l y d i s l o c a t i o n s 8- d i s l o c a t i o n bands motion. Moments o f s c r a t c h i n g being charged which have in their cores the dangling a r e i n d i c a t e d by needles /13/.
bonds /17,18/. The d i s l o c a t i o n l i n e charge q p r o v e d The magnitude q can be determined by formula ( 7 ) aP- to be very sensitive to some Dhysical conditions p l y i n g t h e e l e c t r i c a l f i e l d t o t h e samples and mea- ( i 11 urnination, temperature, motion velocity). Figure s u r i n g t h e parameters o f mechanical ~ r o o e r t i e s . The Shows the dependence o f on the incident light parameters can be t h e d i s l o c a t i o n v e l o c i t i e s o r t.he wavelength /14/ in ZnSe. As it is seen from the figu- p l a s t i c d e f o r m a t i o n r a t e . T h i s method has been employ- re the dislocation charge increases on being
e d t o measure d i s l o c a t i o n charges i n ZnS /3,15/ ( F i g . nated by light the wave length o f which is close to 5 ) . Thus* a s we have seen the O f the
t h e edge o f fundamental a b s o r ~ t i o n (hv z 2.6 eV).
l i n e a r charge determines b o t h t h e d i s l o c a t i o n c u r r e n t s and t h e f o r c e a f f e c t i n g a charged d i s l o c a t i o n i n t h e ,
e x t e r n a l e l e c t r i c f i e l d . That i s t o say, t h a t t h e d i s l o c a t i o n charge i s " a t t a c h e d " t o t h e d i s l o c a t i o n l i n e .
3
1
3 m
4 -
- 2 ~ v on
F i g . 6 : Dependence o f q i n ZnS on wave-length o f i n c i d e n t l i g h t /14/.
T h i s l i g h t e f f e c t t a k e s p l a c e uo t o t h e photon ener- g i e s w h i c h a r e a p p r o x i m a t e l y e q u a l , t o a h a l f o f t h e gap. A s i m i l a r i n c r e a s e o f q d u r i n g i l l u m i n a t i o n has a l s o been r e g i s t e r e d i n ZnS /15/, CdS /19/ and CdSe.
0 5 LO is
20 ImIn - I n case o f a t e m p e r a t u r e i n c r e a s e t h e d i s l o c a t i o n charge decreases and t h e dependence q (T) b e i n g p r a c - F i g . 5 : E f f e c t o f e l e c t r i c f i e l d on d e f o r m a t i o n t i c a l l y l i n e a r /14/. I t i s a l s o o f i n t e r e s t t h e s t r e s s i n ZnS /3/. dependence o f q o n d e f o r m a t i o n r a t e in % V d i . e . t h e
d i s l o c a t i o n speed ( F i g . 7 ) /14/
Yet t o f i n d o u t whether some p o r t i o n o f t h e d i s l o c a - A q 2, A l n (T) v d
0 ( 8 )
0 1 2 3 4 5
f - $rn~n) non-doped n - t y p e s i n g l e c r y s t a l s a t room temperature.
-
- d - band -
I
I I
I I
I I
- - - -
1 I I I I I I
?- e l e c t r o n s by t h e moving d i s l o c a t i o n s , we have made
- 1 s '& - measurement o f t h e H a l l e f f e c t i n cases o f b o t h t h e
1 c o n d u c t i o n c u r r e n t s and d i s l o c a t i o n c u r r e n t s . These a measurements made i n ZnSe have shown t h e c o n t r i b u t i o n
10 i s f r e e e l e c t r o n s t o t h e d i s l o c a t i o n c u r r e n t s exceeds 2% n e i t h e r i n darkness n o r i n l i g h t .
3. The d i s l o c a t i o n charges i n A= BPI compounds.- T a b l e I g i v e s summarized r e s u l t s o f measurements o f
l i n e a r d e n s i t y o f t h e d i s l o c a t i o n charge i n A= BE compounds. A1 1 t h e v a l u e s correspond t o t h e measure-
- 0 ments c a r r i e d o u t w i t h n o n - i l l u m i n a t e d and s p e c i a l l y
C 6 - 164 JOURNAL D E PHYSIQUE
As i t ' s seen ( F i g . 7 ) the slope o f s t r a i g h t l i n e s i n -
creases w i t h temperature. f = 1 1 + exp L - 1 - l
, where 9 = = 7 i s - the f i l l i n g c o e f f i c i e n t , a-
I
C
the d i s t a n c e between dangling bonds, c - t h e d i s t a n c e
05 - between t h e e l e c t r o n s trapped i n these bonds. The
, 2'i': < value o f t h e l e v e l E d r i s e s q u i c k l y t o t h e value o f
chemical p o t e n t i a l v , because of t h e Coulomb i n t e r a c - t i o n so t h a t i t s occupation stops. I t gives r i s e t o small values of t h e e x p e r i m e n t a l l y observed f i l l i n g c o e f f i c i e n t f 5 0.1 f o r the immovable d i s l o c a t i o n s . However, one may assume, t h a t i n t h e case o f t h e moving d i s l o c a t i o n f cannot be c a l c u l a t e d by the e q u i l i b r i u m f u n c t i o n (formula 9 ) . Perhaps i t i s due t o t h e f a c t t h a t t h e e l e c t r o n s l o c a l i z e d on t h e p o i n t
I I s , ] d e f e c t s have no time t o come t o thermal e q u i l i b r i u m
W 2 3 4 5 10 20 30 40 50
\ w i t h t h e conduction band when t h e charged d i s l o c a t i o n
(ZV%! - -
m,n asses c l o s e t o them. Namely, t h e occupation o f these l o c a l centers by e l e c t r o n s i n the v i d i n i t y o f t h e Fig. 7 : E f f e c t o f the deformation r a t e on d i s l o c a - moving d i s l o c a t i o n t u r n s o u t t o be much h i g h e r than
t i o n charge i n ZnSe. The En - a x i s i s l o g a r i t h m i c t h e electron occupation near t h e immova- /14/.
b l e d i s l o c a t i o n . One o f t h e p o s s i b l e techniques t o
Table I
M a t t e r i G l i d e i Burgers i D i s l o c a t i o n i q. b/e
(compound) i p l a n e i v e c t o r a x i s
-
1 CdS : (0001) i 1/3 [1210] ( a ) C1120] i 0.39-0.88""w u r t c i t e i (0001) i 1/3 [1210]($) [ l l ? O ] 0.19-0.48'~
j (0001) i 1/3 [ l ~ l O ~ s c r e w s i [1?10] i uncharged
i ( i i o o ) i 1/3 E1210]edge j [ O O O ~ ] i 0 . 1 % ~
i ( l i 0 0 ) i 1/3 [l'ilO]screw i L 1 2 1 0 ] j uncharged
CdSe i (0001) i 1/3 ~ 1 2 1 0 ] ( $ ) i [ l l 2 0 ] 0.14+0.17**
w u r t c i t e i (Cool) i 1/3 1 ~ 1 0 ~ s c r e w i [1210] i uncharged
ZnS (111) 1/6 ~ 1 2 1 1 i ~ i i o a i 0.7+0.gX**
s p h a l e r i t e * i (1111 j 1/2 r . 1 1 0 1 screw uncharged**
; E l i 0 7 i
ZnSe i (111) i 1/2 E l 0 1 1 ( a ) 60" 0.45+0.6*'
s p h a l e r i t e i (111) i 1/2 E l i 0 1 i [lie] i
f ; screw i uncharged
i [ i i o ] i
* S p h a l e r i t e w i t h h i g h d e n s i t y o f (111) s t o c k i n g f a l t s 1161
*x Dangling bonds i n t h e d i s l o c a t i o n core
xxr D i s l o c a t i o n type i s unknown
4. The n a t u r e o f d i s l o c a t i o n charges i n A= Bn Corn- c a l c u l a t e the f i l l i n g c o e f f i c i e n t J f o r t h e moving pounds.- As i t has been p o i n t e d o u t above, i n A~ B~ d i s l o c a t i o n has been developed 191. I n the s i m p l i e s t compounds o n l y t h e d i s l o c a t i o n s w i t h "dangling bonds" a p p r o x i m a t i o n ' i t has been based on t h e assumption have e l e c t r i c a l charges. I n case of t h e O C C U P ~ ~ ~ O ~ t h a t i n a s t a t i o n a r y case t h e e l e c t r o n f l o w from t h e o f t h e d i s l o c a t i o n l e v e l s by e l e c t r o n s p o i n t centers onto t h e d i s l o c a t i o n Ptd i s equals t o
t h e flow from t h e d i s l o c a t i o n s t o t h e conduction band
Y u . A . Ossipyan and V.F. Petrenko
P , . I n t h i s case : t i o n luminescence" /4.9.11/.
where Vd i s t h e d i s l o c a t i o n v e l o c i t y , Wdc - t h e f r e - quency f o r d i s l o c a t i o n - c o n d u c t i o n band t r a n s i t i o n s ; n - t h e e l e c t r o n c o n c e n t r a t i o n on t h e t r a p l e v e l s ,
t
Rlt - " t h e i n t e r a c t i o n r a d i u s " o f t h e l o c a l c e n t e r w i t h t h e d i s l o c a t i o n determined from t h e equation :
RI Wtd(l-f)
Rlt = r o t In [ Vd ] % l o e 6 cm (11)
where rot - o f t h e o r d e r o f i n t e r a t o m i c d i s t a n c e and Wtd i s t h e frequency f o r t h e d i s l o c a t i o n - c e n t e r t r a n - s i t i o n s :
a' - e.h .n -@
- 4 ' Z ' z (12) I
0 10 20 a -
Summation i n formula (10) i s o n l y f o r those centers LO
whose energy l e v e l exceeds the d i s l o c a t i o n l e v e l po-
Fig. 8 : Short-circuit effect in ZnS. 295 K. The
s i t i o n by t h e value : deformation r a t e i s 20 u/min. A t t h e moments 1.3 -
2 e2 r " t d r o t the surfaces o f sample were shorted, a t t h e moments
E -E 5- f I n (A I n ( ---) = 0.4 eV
t d ~ a a 2.4 - were unshorted /3/.
vd 1 - 9 1
l J ) I t has been found t h a t two kinds o f fluorescence -
The deeper t r a p p i n g l e v e l s do n o t g i v e t h e i r elec- t r o n s t o t h e d i s l o c a t i o n . Thus, t h e s t a t i o n a r y elec- t r o n occupation o f t h e moving d i s l o c a t i o n i s accom- p l i s h e d when two kinds f l o w s o f e l e c t r a n s are equal
- from t h e c e n t r e s t o t h e d i s l o c a t i o n and from t h e d i s l o c a t i o n t o t h e conduction band. T h i s model des- c r i b e s experimental dependencies f on I n (Vd) and on T observed i n ZnSe s u f f i c i e n t l y w e l l .
5. The p h y s i c a l phenomena due t o t h e movement o f char- ged d i s l o c a t i o n s . - D i s l o c a t i o n c u r r e n t s (Fig. 2) and t h e odd e l e c t r o p l a s t i c e f f e c t (Fig. 5 ) described above, can be considered as t h e s i m p l i e s t o f t h i s k i n d of phenomena. T h i s group i n c l u d e s a l s o t h e so- c a l l e d " s h o r t - c i r c u i t e f f e c t " / 3 / . I n comparison w i t h t h e usual deformation, t h e e f f e c t c o n s i s t s i n decrea- se o f t h e f l o w s t r e s s i n t h e case o f t h e s h o r t c i r - c u i t i n g t h e opposite surfaces i n t h e specimen (Fig.
8). ~t i s due t o a dependence o f t h e e l e c t r i c f i e l d E on boundary c o n d i t i o n s o r i g i n a t i n g when transpor- t i n g t h e charge by d i s l o c a t i o n s . I n t h e case of s h o r t c i r c u i t E=O, w h i l e f o r t h e usual deformation i t can reach t h e value E%lOS V/cm. Thus, t h e phenomenon can be considered as a v a r i e t y o f the odd e l e c t r o - p l a s t i c e f f e c t (Fig. 5 ) .
The o t h e r group o f ' t h e e f f e c t s due t o t h e mo- vement o f charged d i s l o c a t i o n s i n A= B= compounds covers phenomena which we have c a l l e d " t h e deforma-
the p u l s e and continuous - occur i n A= B* c r y s t a l s , subjected t o mechanical s t r e s s pulses producing a weak p l a s t i c deformation. Both k i n d s o f fluorescence
proved t o be caused by the movement o f charged d i s l o - c a t i o n s . The mechanism o f t h e p u l s e fluorescence i s due t o t h e f o l l o w i n g f a c t o r s : t h e t r a n s p o r t o f e l e c - t r i c charge by d i s l o c a t i o n s i n t o t h e c r y s t a l surface, the generation o f a s t r o n g e l e c t r i c f i e l d t h e r e and t h e electroluminescence by t h e a c t i o n o f t h i s f i e l d . I f the c r y s t a l i s placed i n t o t h e e l e c t r o c o n d u c t i v e o p t i c a l l y t r a n s p a r e n t l i q u i d (KC1 s o l u t i o n ) - t h e e1ectroconductivit.y of which prevents t h e charge from accumulating on the c r y s t a l surface, t h e p u l s e luminescence d i s a p ~ e a r s . I n case o f the absence o f t h e ~ u l s e luminescence the c r y s t a l r e v e a l s c l e a r l y t h e s t a t i o n a r y deformation luminescence. I t i s asso- c i a t e d w i t h t h e i o n i z a t i o n o f l o c a l centers by char- ged d i s l o c a t i o n s i n s i d e t h e c r y s t a l and then w i t h processes o f the recombination.
We succeeded i n observing t h e l i g h t / l o / and e l e c t r i c a l f i e l d e f f e c t /4/ on t h e deformation lumi- nescence i n t e n s i t y . T h i s e f f e c t probablv has t h e same n a t u r e as t h e . p h o t o p l a s t i c and e l e c t r o p l a s t i c e f f e c t s .
The d i s l o c a t i o n movement influences a l s o the.
c o n d u c t i v i t y and the p h o t o c o n d u c t i v i t y o f t h e A II:
compounds.
C6-166 JOURNAL DE PHYSIQUE
I t has t u r n e d o u t t h a t as t h e d i s l o c a t i o n s move i n ZnSe t h e dark c o n d u c t i v i t y r i s e s and the photocon- d u c t i v i t y decreases. The dark c o n d u c t i v i t v increase i s l i k e l y t o be due t o t h e i o n i z a t i o n o f t h e deep im- p u r i t y l e v e l s i n e l e c t r i c f i e l d s o f the movinq char- qed d i s l o c a t i o n s . A t o t a l number o f the i o n i z e d imou- r i t i e s ( l o 7 t l o 9 ~ m - ~ ) i n t h i s k i n d o f processes i s o n l y a small p a r t o f t h e i r c o n c e n t r a t i o n ( l o 1 * a 1016 cm- 9).
The d i s l o c a t i o n c u r r e n t measurinq enables one t o determine very small values o f the p l a s t i c defor- ination and i t s r a t e s ;%lo-' cm-l. T h i s can be performed by a p p l y i n g t h e expression Id % En.
Studies o f the charged d i s l o c a t i o n movement bv means o f measuring the d i s l o c a t i o n c u r r e n t s a l l o w s one t o o b t a i n dependencies on temperature, a p p l i e d s t r e s - ses i n c i d e n t l i g h t wavelength and etc. The f i n d i n g s o f these i n v e s t i g a t i o n s (Figs. 9-10) have demonstra- t e d t h a t t h e v e l o c i t y o f d i s l o c a t i o n movenent i n A TI
compounds i s o f a thermoactivated c h a r a c t e r and i t can be described by formula :
vd % exp C- E o + a Tq - yT7
Fig. 9 : Dependence o f t h e p l a s t i c f l a w s t r e s s T on t h e value o f d i s l o c a t i o n chargb. A,e - a t darkness,
A,O - a t i l l u m i n a t i o n /14/.
For ZnSe : Eo = 0.00 + 0.03 eV, a = 5 x loi3 (e/b) erg, y = (20 + 2 ) b3. The standard a n a l y s i s u s u a l l y
made d u r i n g t h e s i m i l a r s t u d i e s has shown t h a t t h e most probably mechanism o f t h e d i s l o c a t i o n movement i n A= B= compounds i s t h e P e i e r l s mechanism. Pecu- 1 i a r i t y o f A= B* comnounds c o n s i s t s i n depending o f t h e h e i g h t o f t h e P e i e r l s b a r r i e r s on t h e l i n e a r char- ge o f t h e d i s l o c a t i o n charge (see formula 14).
Fig. 10 : Deoendences of l i n e a r d e n s i t y o f d i s l o c a - t i o n charges q and p l a s t i c f l o w stresses on tempera- t u r e f o r ZnSe /14/.
To i n t e r p r e t t h i s dependence t h e model was o f f e r e d /19/ assuming t h e P e i e r l s b a r r i e r s are formed by e l e c - t r o s t a t i c i n t e r a c t i o n between t h e charged d i s l o c a - t i o n and c r y s t a l l i n e l a t t i c e ions. T h i s model a o ~ l i - ance allows t o describe a l l t h e p l a s t i c e f f e c t s known i n A* B* : p h o t o p l a s t i c /5/, e l e c t r o p l a s t i c /7/, negative photopl a s t i c /6/, i m p u r i t y p h o t o p l a s t i c /21/, deformation 1 uminescence /9/, s h o r t - c i r c u i t e f f e c t 131.
References
/1/ Stepanov, A.V., Z. Phys., 81 (1933) 560.
/2/ Whitworth, R.W., Adv. Phys., 24 (1975) 203.
/3/ Ossipyan, Yu. A., Petrenko, V.F., JETP, 69
(1975) 1362-1371.
/4/ B r e d i k h i n , S. I . , Shmurak, S.Z., Pisma v JETP, 21 (1975) 342.
-
/5/ Ossipyan, Yu. A., Savchenko, 1.6. , Pisma c JETP, 7 (1968) 130-132.
-
/6/ Ossipyan, Yu. A., Shikhsaidov, Y.Sh., FTT, -5l (1973) 3711-3713.
/7/ Ossipyan, Yu. A., Petrenko, V. F., Pisma v JETP, 17 (1973) 555-557.
-
/8/ S a r e c k i i , A.V., Ossipyan, Yu. A. and Petrenko, V.F., FTT, - 20 (1978) 1442.
/9/ B r e d i k h i n , S.I., Shmurak, S.Z., Pisma JETP, 2
(1974) 709.
/ l o / Bredi k h i n , S. I. , Ossipyan, Yu. A. and Shmurak, S.Z., JETP, 68 (1975) 750.
/11/ B r e d i k h i n , S. I., Shmurak, S.Z., JETP, 73 (1977)
1460.
Yu. A . Ossipyan and V.F; Petrenko
/12/ S a r e c k i i , A.V., Petrenko, V.F., FTT, (1978) 1167 /13/ S a r e c k i i , A.V., Ossipyan, Yu. A., Petrenko, V.F.
and Strukova, G. K. , FTT, 19 (1977) 418-423.
/14/ Kirichenko, L . G . , Petrenko, V.F. .and Uimin, G.V., JETP, 74 (1978).
/15/ Ossipyan, Yu. A., Petrenko, V.F., DAN, 226 N4 (1976) 802-805.
/16/ Abdikamalov, B.A., Bredikhin, S.I., Kulakov, Y.
P., Shekhtman, V.Sh. and Shmurak, S.Z., FTT. 2
(1976) 2448.
/17/ H o l t , D.B., 3. Phys. Chem. S o l i d s , 23 (1962) 1353.
/18/ Ossipyan, Yu. A., Smirnova, I.S., Phys. Status S o l i d i , 3 (1968) 19-29.
/19/ Ossipyan, Yu.A., Petrenlo, V.F., JETP, 74
(1978).
/20/ Read, W . , P h i l o s . Mag., 45, (1954) 1119; P h i l o s . Mag. , 45 (1954) 775.
/21/ Ossipyan, Yu. A., Petrenko, V.F. and Shikhsaidov, 3. Sh., Pisma JETP, (1974) 363.
