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S. H. C A R P E N T E R

D i s l o c a t i o n m o b i l i t y has b e e n s t u d i e d in heavily doped s i l i c o n single c r y s t a l s by kilohertz i n t e r n a l f r i c t i o n m e a s u r e m e n t s . The dopant effect on d i s l o c a t i o n m o b i l i t y p r e v i o u s l y r e p o r t e d in g e r m a n i u m and s i l i c o n u n d e r p l a s t i c d e f o r m a t i o n has now b e e n s e e n i n s i l i c o n u n d e r the i n f l u ence of much lower applied s t r e s s e s . The low s t r a i n s and only m o d e r a t e l y e l e v a t e d t e m p e r a t u r e s used in the p r e s e n t i n v e s t i g a t i o n allow the d i s l o c a t i o n s to o s c i l l a t e only s l i g h t l y about t h e i r e q u i l i b r i u m p o s i t i o n s . The r e s u l t s from the slight d i s l o c a t i o n e x c u r s i o n s have led to a unified kink model of d i s l o c a t i o n d a m p i n g in s i l i c o n . The dopant effect on d i s l o c a t i o n m o b i l i t y is a t t r i b u t e d d i r e c t l y to the s u r p l u s e l e c t r o n i c c a r r i e r s in the i m m e d i a t e v i c i n i t y of the d i s l o cation kink. The i n t r i n s i c c a r r i e r c o n c e n t r a t i o n in the local v i c i n i t y of the d i s l o c a t i o n has b e e n found to be 100 t i m e s g r e a t e r than the c o r r e s p o n d i n g bulk value. / H E d i s l o c a t i o n m o b i l i t y under the influence of p l a s tic d e f o r m a t i o n in e l e m e n t a l s e m i c o n d u c t o r s has b e e n p r e v i o u s l y studied by other i n v e s t i g a t o r s . 1'2 In the case of g e r m a n i u m where etch pitting of the s u r f a c e was f e a s i b l e the method of Stein a n d Low was used. 3 F o r the case of s i l i c o n where r e p r o d u c i b l e etch pitting was not a m m e a n a b l e , Lang X - r a y topography was used to locate the position of the d i s l o c a t i o n s which i n t e r s e c t e d the s u r f a c e . In e i t h e r case the location of p a r t i c u l a r d i s l o c a t i o n s u r f a c e i n t e r s e c t i o n s was known b e f o r e and a f t e r the application of a s t r e s s pulse of known magnitude and d u r a t i o n . The r e l a t i v e l o c a t i o n s were used to a s c e r t a i n the a v e r a g e d i s l o c a t i o n v e l o c i t y for individual d i s l o c a t i o n s . As a r e s u l t of the p r e v i o u s work, c h a r g e d dopant i m p u r i t y c o n c e n t r a t i o n s have b e e n o b s e r v e d to m a r k edly effect the d i s l o c a t i o n v e l o c i t y in the h e a v i l y doped s e m i c o n d u c t o r c r y s t a l s . As an a c c e p t o r i m p u r i t y level is i n c r e a s e d in s u c c e s s i v e c r y s t a l s the v e l o c i t y i s obs e r v e d to d e c r e a s e . C o n v e r s e l y , if a donor doping l e v e l is i n c r e a s e d the d i s l o c a t i o n velocity i n c r e a s e s . The effect has been r e p o r t e d in n - a n d p - t y p e g e r m a n i u m 1 and n - t y p e s