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S. KULKARNI,

D. P. POPE,

C. D. GRAHAM,

Jr., AND

C y l i n d r i c a l s a m p l e s of p o l y c r y s t a l l i n e s e m i c o n d u c t o r - g r a d e s i l i c o n have been c o m p r e s sed 30 pct at 1380~ at a r a t e of 0.08 s -1. The s t a r t i n g m a t e r i a l had a s t r o n g (110} fiber texture, r e s u l t i n g f r o m its growth by c h e m i c a l vapor deposition; the f i b e r axis was p e r p e n d i c u l a r to the c o m p r e s s i o n axis. The c o m p r e s s i o n texture is v e r y c l e a r l y defined after only 30 pct deformation, and has a (110) axis p a r a l l e l to the c o m p r e s s i o n axis and a (111} axis p a r a l l e l to the o r i g i n a l (110} f i b e r axis (perpendicular to the c o m p r e s s i o n axis). Annealing for 10 min a t 1380~ causes r e c r y s t a l l i z a t i o n . The r e c r y s t a l l i z a t i o n t e x t u r e has a (100} axis p a r a l l e l to the c o m p r e s s i o n axis, and a (110} axis p a r a l l e l to the o r i g i n a l (110) f i b e r axis. C o m p r e s s i o n of a r e c r y s t a l t i z e d s a m p l e gives the s a m e deformation texture as does c o m p r e s s i o n of the o r i g i n a l m a t e r i a l . A S p a r t of a r e s e a r c h p r o g r a m to d e t e r m i n e the f e a s i b i l i t y of h o t - r o l l i n g s i l i c o n sheet for photovoltaic power generation, we have i n v e s t i g a t e d the d e f o r m a tion of p o l y c r y s t a l l i n e s i l i c o n by c o m p r e s s i o n at t e m p e r a t u r e s f r o m ll00~ to the melting point (1420~ for a s e r i e s of s t r a i n r a t e s up to about 0.1 s -x. In this p a p e r we r e p o r t on the c r y s t a l l o g r a p h i c t e x t u r e s p r o duced by c o m p r e s s i o n and by r e c r y s t a l l i z a t i o n ; the m e c h a n i c a l p r o p e r t y data and m e t a l l o g r a p h i c r e s u l t s will be r e p o r t e d s e p a r a t e l y . SAMPLE

PREPARATION

The s t a r t i n g m a t e r i a l was s e m i c o n d u c t o r grade p o l y c r y s t a l l i n e s i l i c o n p r e p a r e d by c h e m i c a l vapor deposition (CVD) f r o m t r i c h l o r o s i l a n e . The s i l i c o n was in the f o r m of a "log" o r cylinder about 150 mm in diam. The growth d i r e c t i o n is r a d i a l , and the growth p r o c e s s r e s u l t s in columnar grain s t r u c t u r e with the long axis of the g r a i n s e v e r y w h e r e p a r a l l e l to the log r a d i u s . P r e v i o u s work 1 has shown that t h e r e is a s t r o n g (110) f i b e r t e x t u r e whose axis is p a r a l l e l to the r a d i a l growth d i r e c t i o n . T h i s texture is not changed by annealing for t i m e s up to s e v e r a l hours at 1380~ although the grain s i z e is substantially i n c r e a s e d (see F i g . 1). C o m p r e s s i o n s a m p l e s in the f o r m of c y l i n d e r s 12 mm long mad 8 mm in diam were cut f r o m the polyc r y s t a l l i n e log using a diamond c o r e d r i l l . The axis of the s a m p l e cylinder