InSb MIS structures for infrared imaging devices

Abstract

General I2leci:ric C0mpan.y Imaging Devices Operation Syracuse, New York InSb metal-insulator-semiconductor (MIS) s t r u c t u r e s w i t h e x c e l l e n t i n t e r f a c e p r o p e r t i e s , measured a t 7 7 O R , have been developed. From t h e dark current measurements, the storage-time for CCD o r C I D t y p e o p e r a t i o n was determined to be in the 0.2 seconds range. The 6-t measurements of t h e most r e c e n t d e v i c e s i n d i c a t e a d a r k c u r r e n t s t o r a g e time of up %o 0.7 seconds. The s t o r a g e mode of c h a r g e i n j e c t i o n o p e r a t i o n (CID) w i t h s i n g l e c e l l InSb MIS s t r u c t u r e s h a s b e e n d e m o n s t r a t e d u s i n g i n f r a r e d i r r a d i a t i o n . However, f o r t h e s t o r a g e d e v i c e s t o o p e r a t e i n ER a p p l i c a t i o n s , t h e b a c kground photon flux i s a major problem since i t i n t e g r a t e s b o t h t h e b a c k g r o u n d a n d s i g n a l i r r a d i at i o n . A new approach t o r e d u c e t h e e f f e c t of background photon flux on the charge storage operation of t h e devLce i s proposed, along with a d e s c r i p t i o n of t h e p e r t i n e n t i n t e r f a c e p r o p e r t i e s . T h i s new t e c h n i q u e u s e s m u l t i -g a t e e l e c t r o d e s t r u c t u r e s combined wit:h t h e c h a r g e -c o MOS s t r u c t u r e s , have received considerable attent i o n i n t h e l a s t few y e a r s , and considerable prog r e s s h a s b e e n made i n b o t h l i n e a n d a r e a imaging d e v i c e s i n t h e v i s i b l e s p e c t r u m . F o r I R a p p l ic a t i o n s a similar approach, using the narrow-bandgap semiconductor, T.nSb, h a s b e e n i n v e s t i g a t e d . Based on o u r r e c e n t r e s e a r c h and development work w i t h t h e In.Sb metal-insulator-semiconductor (MIS) technology, we ha.ve f a b r i c a t e d MIS s t r u c t u r e s w i t h e x c e l l e n t i n t e r f a c e p r o p e r t i e s . T h e s e s t r u c t u r e s a l s o o p e r a t e i n t h e c h a r g e s t o r a g e mode based on t h e s u r f a c e c h a r g e -c o u p l i n g p r i n c i p l e . The r e s u l t s of the,se i n i t i a l e f f o r t s w i l l . b e p r e s e n t e d and a new a p p r o a c h t o s t o r a g e o p e r a t i o n i n t h e I R r e g i o n will be proposed. Typi.ca1. c a p a c i t a n c e -v o l t a g e c h a r a c t e r i s t i c s of a11 n-type InSb MIS c a p a c i t o r a t v a r i o u s f r e q u e nc i e s a r e shown i n F i g u r e 1. The measurements were made a t 7 7 O R i n t h e d a r k , s o t h a t no photon flux cou1.d c o n t r i b u t e t o t h e m i n o r i t y c a r r i e r r e l a x a t i o n process. As shown, t h e C-V c h a r a c t e r i s t i c s f o l l o w t h e s i m p l e i d e a l MIS capacitance model. The low measurement frequency a t w h i c h t h e c a p a c i t a n c e , a t t h e o n s e t of t h e s t r o n g i n v e r s i o n , c o i n c i d e s w i t h t h e i n s u l a t o r c a p a c i...