Charge mobility is a key parameter for understanding the performance of organic semiconductor devices and materials. A range of techniques is available that can measure charge mobility with varying accuracy and precision. In this paper we analyze the dark injection transient current (DITC) method from a metrology perspective. We carried out a systematic study of the sensitivity of single carrier analogues of organic light-emitting diodes (OLEDs) to small changes in electrical input and environmental conditions. We observed that the experimental results depend strongly on the previous history of the device under test, with both long term and short term effects in evidence. Our findings demonstrate the need for caution in interpreting the results of single experiments to determine the charge mobility of OLEDs and the difficulty of associating uncertainty statements with the results of charge mobility measurements.

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Charge mobility is a key parameter for understanding the performance of organic semiconductor devices and materials. A range of techniques is available that can measure charge mobility with varying accuracy and precision. We review the dark injection transient current method from a metrology perspective with a particular emphasis on quantification of uncertainties that arise from the technique itself and from the inherent variability of devices and materials. We have carried out a systematic study of the space-charge-limited dark injection transient current technique as a method of measuring charge mobility in polymer organic light emitting diodes, paying particular attention to varying the amplitude, duration and repetition rate of the applied voltage and to environmental factors such as changes in the ambient temperature. We show that the results of the experiment depend strongly on the previous history of the device and that both long-term and short-term effects can be identified. As a result, we are able to quantify the contribution of these effects to the uncertainties associated with estimates of charge mobility obtained using the dark injection method.

I n t e l C o r p o r a t i o n 3 6 0 1 J u l i e t t e Lane Santa Clara, Ca. 95051 (408) 496-7294 I n t h e F l o t o x ( f l o a t i n g -g a t e t u n n e l o x i d e ) EEPROM t e c h n o l o g y , ( 2 ) a n u l t r a t h i n t h e r m a l o x i d e (around 110 i) h a s b e e n u s e d a s t h e F~w l e r -N o r d h e i m (~) t u n n e l p a t h . B o t h erase and write a r e accomp l i s h e d by t u n n e l i n g t h e e l e c t r o n b e t w e e n t h e f l o a t i n g p o l y s i l i c o n g a t e a n d N d r a i n r e g i o n . The i n t e g r i t y o f t h e t u n n e l o x i d e becomes i n a d e q~a t e '~) f o r a d i e l e c t r i c t h i c k n e s s b e l o w 8 0 w h i c h i s a n e s s e n t i a l r e q u i r e m e n t f o r a 12 V e r a s e / w r i t e EEPROM. High temperature ammonia-annealed oxide h a s b e e n s u g g e s t e d ( 7 ) a s a n a l t e r n a t i v e t u n n e l d i e l e c t r i c b e c a u s e t h e n i t r i d i z e d o x i d e h a s a h i g h breakdown c a p a b i l i t y a n d l o w e r t u n n e l b a r r i e r . U n f o r t u n a t e l y , t h i s n i t r i d i z e d o x i d e e x h i b i t s h y t e r s i s i n s t a b i l i t y d u e t o n i t r i d a t i o n -i n d u c e d t r a p s .+ ( 5 ) ( 6 ) ( 8 ) I n o r d e r t o l o w e r t h e programming voltage and improve the endurance of EEPROM, o x i d i z e d -n i t r i d i z e d o x i d e (ONO) (') has been developed and demonstrated in 16 kb EEPROM. E v a l u a t i o n t e c h n i q u e s ( l O ) a r e based on ( i ) l o g I -V a t c o n s t a n t ramp r a t e t o d e t e r m i n e t h e t r a p b e h a v i o r v s . c u r r e n t s t r e s s . ( i i ) C-V t o d e t e r m i n e t h e s u r f a c e s t a t e b e h a v i o r a n d d i f f e r e n t i a t e i t f r o m t r a p p i n g . ( i i i ) V ( t ) a c r o s s t h e t h i n d i e l e c t r i c f o r a c o n s t a n t s t r e s s t o d e t e r m i n e t h e t o t a lamount of charge trapped b e f o r e d i e l e c t r i c b r e a k d o w n . ( i v ) J . t u n d e r c o n s t a n t c u r r e n t stress t o d e t e r m i n e t h e t o t a l c h a r g e p a s s e d t h r o u g h d i e l e c t r i c p e r u n i t a r e a b e f o r e d i e l e c t r i c b r e a k d o w n . Charge trapping was c o r r e l a t e d w i t h n i t r i d a t i o n t e m p e r a t u r e / t i m e , o x i d a t i o n t e m p e r a t u r e / t i m e and J ' t y i e l d . It will be shown t h a t t h e t h r e s h o l d window, d e f i n e d a s t h e d i f f e r e n c e b e t w e e n t h e e r a s e and write t h r e s h o l d , r e m a i n s a l m o s t c o n s t a n t u n t i l 1 0 e r a s e / w r i t e c y c l e s owing t o t h e e x t r e m e l y l o w c h a r g e t r a p p i n g i n ON0 f i l m s u n d e r h i g h -f i e l d stress. 65 ON0 f i l m s show s i g n if i c a n t l y b e t t e r J -t y i e l d t h a n o x i d e o r n i t r i d i z e d o x i d e , t h e ON0 f i l m a p p e a r s v e r y p r o m i s s i n g a s a t u n n e l d i e l e c t r i c i n t h e I2 V e r a s e / w r i t e EE...

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