EFFECTS OF THE SUBSTRATE POTENTIAL ON THE INCORPORATION MANNER OF HYDROGEN AND IMPURITY IN a-Si : H FILMS

(1)

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EFFECTS OF THE SUBSTRATE POTENTIAL ON THE INCORPORATION MANNER OF HYDROGEN

AND IMPURITY IN a-Si : H FILMS

S. Hotta, Y. Tawada, H. Okamoto, Y. Hamakawa

To cite this version:

S. Hotta, Y. Tawada, H. Okamoto, Y. Hamakawa. EFFECTS OF THE SUBSTRATE POTENTIAL ON THE INCORPORATION MANNER OF HYDROGEN AND IMPURITY IN a-Si : H FILMS.

Journal de Physique Colloques, 1981, 42 (C4), pp.C4-631-C4-634. �10.1051/jphyscol:19814138�. �jpa-

00220758�

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J O U R N A L DE PHYSI()UE

CoZZoque C4, supp26mment czu z0i!7, Tome

4 2 ,

octobre 1981 page

C4-631

EFFECTS OF THE SUBSTRATE P O T E N T I A L ON THE INCORPORATION FlANNER OF HYDROGEN AND I M P U R I T Y I N a - S i : H F I L M S

S. ~ o t t a * , Y. ~ a w a d a Y * , H. Okamoto and Y. Hamakawa

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A b s t r a c t . -

E f f e c t s o f the b i n s voltuge applied t o Lhe su3atrate on the f i l m r;roper-ties o f a-Si:Il have been i n v e s t i g a t e d bg employing t h e cross f i e l d

;lasma d e ~ ~ s i t i o n method.

A

c l e a r and continuous interchange i n t h e i n f r a r e d a b s o ~ i t i o n peaks om 2090*

em-]

t o 2000 has been observed by changing ,polar>ity and magnitude o f the b i a s vol-tage. Mor,eover, d r n s t i c u l change i n t h e im:>urity doping e f f i c i e n c y and optimvn? b i a s v o l f a g e r e l a t e d w i t h r y o v e r have been founi.

13y

means oj' t h e opticrrl m i s s i o n spectr20scopy (OE:;'), i t was zon- firmed Lkat t h e substr.atc: potentiai? is a s m ~ c h e f f e ~ t i v e i n deterwining the J.iZm prot.,r:rLies a s t h e kind oj^ decomposed species i n t h e p o s i t i v e col7mn.

I n t r o d u c t i o n . - I n h y d r o g e n a t e d amorphous S i f i l m s p r e p a r e d by plasma d e p o s i t i o n f r o m m o n o s i l a n e , t h e r e a r e t o o many p a r a m e t e r s i n d e t e r m i n i n g t h e i n c o r p o r a t i o n manner o f h y d r o g e n and i m p u r i t y atorns a n d t h e r e b y s t r u c t u a l a n d e l e c t r o n i c p r o p e r t i e s [ l , 2 , 3 , 4 ] . W h i l e , a s d e m o n s t r a t e d by FRITZSCHE[4], K N I G H T s [ ~ ] , TSAI [ 6 ] a n d OKAMOT0[7], s u r f a c e p o t e n t i a l a t t h e s u b s t r a t e a l s o h a s a s i g n i f i c a n t i n f 1 1 1 e n r . e o n t h e o v e r a l l p r o p e r t i e s o f a - S i : H f i l m s a s w e l l a s o t h e r c o n v e n t i o n a l d e p o s i t i o n p a r a m e t e r s ; s u b s t r a t e t e m p e r - a t u r e , gas p r e s s u r e , gas f l o w r a t e , r f power and so f o r t h . F o r a f u r t h e r d e t a i l e d r e c o g n i t i o n o f s u r f a c e p o t e n t i a l e f f e c t s , we have c o n d u c t e d a s y s t e m a t i c i n v e s t i g a - t i o n s hy e m p l o y i n g t h e c r o s s f i e l d plasnia d e p o s i t i o n m e t h o d [ 7 ] w h i c h makes i t p o s s i b l e t o c o n t r o l t h e s u b s t r a t e p o t e n t i a l s e p a r a t e l y f r o m o t h e r d e p o s i t i o n p a r a m e t e r s .

T h i s p a p e r p r e s e n t s a s e r i e s o f e x p e r i m e n t a l d a t a o n t h e h y d r o g e n and b o r o n i n c o r p o r a t i o n , t h e e l e c t r i c a l , o p t i c a l and o p t o e l e c t r o n i c p r o p e r t i e s o f undoped and i m p u r i t y doped a - S i : H f i l m s d e p o s i t e d u n d e r t h e e x t e r n a l l y b i a s e d c o n d i t i o n . B e s i d e s , s i n c e optical-emission-spectroscopy(0ES) o f a s i l a n e g l o w d i s c h a r g e i s , i n t h e g e n e r a l c o n c e n s u s , e x p e c t e d t o b e a u s e f u l t o o l f o r

u n d e r s t a n d i n g t h e p l a s m a c h e m i s t r y [ 8 ] , we a l s o d i s c u s s t h e r e s u l t s o f OES d u r i n g t h e plasma d e c o m p o s i t i o n w i t h b i a s e d c o n d i t i o n i n c o n - j u n c t i o n w i t h t h e f i l m p r o p e r t i e s .

C r o s s f i e l d plasma d e o s i t i o n s y s t e m . -

F i g u r e I shows a s c h e P a t i c i I l u s t r a t :on o f t h e d e o o s i t i o n s v s t e m ernDloved i n t h e w o r k . The _, _, plesma was e x c i t e d b y 13.56 M H ~ r f o s c i l l a t e r t h r o u g h t h e s y m m e t r i c c o u p l i n g e l e c t r o d e s A a n d B s e t t l e d o u t s i d e t h e r e a c t i o n t u n n e l chamber o f 14 cm i n d i a m e t e r , 2 5 cm i n h i g h t . An a d d i t i o n a l d c e l e c t r i c f i e l d was s u p e r -

imposed p e r p e n d i c u l a r l y t o r f e l e c t r i c f i e l d by u s i n q two p a r a l e l l e l e c t r o d e s C and D

s e p a r a t e d by 14 cm. S u b s t r a t e m a t e r i a l s were

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Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19814138

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C4-632 JOURKAL DE PHYSIQUE

t h i s d e p o s i t i o n system i s t h a t t h e s u b s t r a t e p o t e n t i a l w i t h r e s p e c t t o t h e plasma can be c o n t r o l l e d i n d e p e n d e n t l y f r o m t h e e n e r g y d e n s i t y o f t h e plasma e x c i t e d by r f e l e c t r i c f i e l d [ 9 ] . The d i s t a n c e between t h e c e n t e r o f t h e r f c o u p l i n g e l e c t r o d e s and s u b s t r a t e was f i x e d t o be 1 1 crn t h r o u g h o u t t h e p r e s e n t work. A dc b i a s v o l t a g e Vb a p p l i e d between t h e e l e c t r o d e s C and D, t h a t i s V D - V C , was v a r i e d f r o m -150 t o +150V.

F i g u r e 2 shows t h e Ib-Vb c h a r a c t e r i s t i c s . As t h e e l e c t r o d e C i s l o c a t e d deep i n t h e p o s i t i v e column, t h e i o n c u r r e n t i n t o t h e

-200 -100

e l e c t r o d e C c o u l d c a n c e l o u t t h e s a t u r a t i o n

--.

e l e c t r o n c u r r e n t i n t o t h e e l e c t r o d e D. There-

f o r e , t h e b i a s v o l t a g e Vb i s f a i r l y i d e n t i c a l w i t h t h e s u b s t r a t e p o t e n t i a l VD. R e g a r d i n g t h i s

-

0 35;v c h a r a c t e r i s t i c s a s t h a t o f LANGMUIR plasma

- 2 -

0 5 5 w I l r .

2 5 0 " ~ d i a g n o s t i c p r o b e [ l O ] , t h e v o l t a g e Vb a t lb=0 i n 6 0 ~ ~ 2-3 i.,, F i g . 2 i n d i c a t e s t h e f l o a t i n g p o t e n t i a l V f a t

w h i c h e q u a l number o f e l e c t r o n s and i o n s a r r i v e :.fe. 7 1:

.. -

Y. ^Uc h r c c : e ~ ; s t i c s o f ~ i i i ⁴/si ??ow a t a s u r f a c e . The c h a r a c t e r i s t i c v o l t a g e V _; a'isc&zryr a s c . ~ , c r m e t c r of rj- power. so c a l l e d t h e plasma p o t e n t i a l , above w h i c t a

c u r r e n t l b ( m a i n l y e l e c t r o n c u r r e n t t o t h e e l e c t r o d e D) s a t u r a t e s i n t h e f i r s t q u a d r a n t i n F i g . 2 i s t h e space p o t e n t i a l i n t h e plasma. I n t h e case o f a f l a t bed system t r i e d , f o r example,by KNIGHTS e t a l . [ 4 , 5 , 6 ] , t h e s u b s t r a t e p o t e n t i a l i s e s s e n t i a l l y modurated by t h e a p p l i e d r f v o l t a g e [ l 0 ] and c o u l d n o t be e x t e r n a l l y c o n t r o l l e d f r e e l y [ l l ] . On t h e c o n t r a r y , i n o u r system, as t h e e l e c t r o d e s C and D a r e e l e c t r i c a l l y i s o l a t e d f r o m t h e r f c i r c u i t , t h e s u b s t r a t e p o t e n t i a l can be d e f i n i t e l y c o n t r o l l e d s t a b l y by s e t t i n g o f Vb.

Amorphous Si:H f j l r n s were d e p o s i t e d o n t o 7059 C o r n i n g g l a s s o r h i g h r e s i s t i v e c r y s t a l l i n e S i w a f e r f r o m m o n o s i l a n e , m o n o s i l a n e / p h o s p h i n e o r m o n o s i l a n e / d i b o r a n e m i x t u r e d i l u t e d w i t h hydrogen gas t o 3-10 v o l . % a t t h e s u b s t r a t e t e m p e r a t u r e o f 250°C.

T o t a l gas f l o w was m a i n t a i n e d t o be 60-80 sccm w i t h a p r e s s u r e o f 1-2 t o r r and i n p f t power was 55W. Under t h e s e c o n d i t i o n s , t h e d e p o s i t i o n r a t e s were 0.7, 1.2 and 1 . 1 A/

sec f o r P-doped, B-doped and undoped f i l m s , r e s p e c t i v e l y . These d e p o s i t i o n r a t e s a r e a l m o s t independent o f t h e p o l a r i t y and m a g n i t u d e o f t h e b i a s v o l t a g e Vb l e s s t h a n 4 150 V. T h i s f a c t means t h a t t h e b i a s v o l t a g e a p p l i e d between t h e e l e c t r o d e s D and C does n o t d i s t u r b t h e plasma d e c o m p o s i t i o n p r o c e s s i n t h e p o s i t i v e column.

E f f e c t s o f t h e b i a s v o l

t a q e

on hydrogen i n c o r p o r a t i o n . -

As t h e f i r s t s t e p i d e n t i f ic a - t i o n o f a - S i : H f i l m s p r o d u c e d by c r o s s f i e l d method, i r a b s o r p t i o n s p e c t r a measurements were made w i t h f i l m s d e p o s i t e d on h i g h p u r i t y

c r y s t a l l i n e S i w a f e r . F i g u r e 3 shows t h e hydrogen c o n t e n t CH and a b s o r p t i o n c o e f f i c i e n t a a t t h e g r o u p ) and 2000 cm-' ( i s o l a t e d monohydrides) a s a f u n c t i o n o f Vb. As seen i n t h e f i g u r e , a c l e a r s t r e t c h i n g mode f r e q u e n c i e s 2090 cm-1

(

d i h y d r i d e

and c o n t i n u o u s i n t e r c h a n g e o f i r a b s o r p t i o n peaks f r o m 2090 t o 2000cm-~ i s o b s e r v e d i n c o r r e s - pondence w i t h t h e v a r i a t i o n o f Vb f r o m t h e p o s i t i v e t o n e g a t i v e v a l u e , even a t t h e s u b s t r a t e t e m p e r a t u r e o f 250°C. The b e n d i n g mode a b s o r p t i o n peaks n e a r 840 and 890cm-I ( d i h ~ d r i d e g r o u p ) have

been a l s o o b s e r v e d i n f i l m s d e p o s i t e d u n d e r t h e 5 5 W l i c m o i b i a s v o l t a g e more t h a n +100V. R e s u l t s o f P-doped

2

2 5 0 "C

f i l m s a l s o e x h i b i t t h e same tendency w i t h t h e . 0

v a r i a t i o n o f Vb. These f a c t s show t h a t t h e nega- ^-100 0 100 t i v e and p o s i t i v e b i a s v o l t a g e promote hydrogen B i a s Vol!age (

v

) atoms t o be i n c o r p o r a t e d m a i n l y as monohydrides Fig.3 liyhogen content cH and absorption and d i h y d r i des, r e s p e c t i v e l y . I n c o n t r a s t t o t h i s , coe,Fficient at Si-H 2ibrationoL mode fpequ- CH a r e a l m o s t independent o f t h e b i a s v o l t a g e and

t h e y a r e a b o u t 16, 17, 1851 a t

.%

f o r undoped,

P-

as a function O f bias voztage.

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doped and B-doped, r e s p e c t i v e l y .

We have c a r r i e d o u t t h e e l e c t r i c a l , o p t i c a l and o p t o e l e c t r o n i c measurements

i n o r d e r t o u n d e r s t a n d how t h e s e d i f f e r e n t i n c o r p o r a t i o n manner o f hydrogen atoms r e f l e c t on t h e p r o p e r t i e s o f a - S i : H f i l m s . F i g u r e

4

show5 t h e n o r m a l i z e d p h o t - o c o n d u c t i v i t y q g r under 1.9eV i l l u m i n a t i o n

(3x 1014photons/sec/cm2) and t h e d a r k con- d u c t i v i t y od a t room t e m p e r a t u r e as a f u n c t i o n o f Vb. As can be seen i n t h e f i g u r e , t h e r e e x i s t s t h e optimum b i a s v o l - t a g e Vop f o r t h e p h o t o c o n d u c t i v e p r o p e r t y o f undoped f i l m s and a t t h i s b i a s v o l t a g e od e x h i b i t s minimum. Vop i s r e l a t e d w i t h r f power as a l s o shown i n F i g . 4 , and t h e v a l u e s o f Vop a r e about 0 and

+

50 V f o r t h e power o f

35W

and

55W,

r e s p e c t i v e l y . The plasma p o t e n t i a l V,, as a l r e a d y r e f e r e d

P:

-,.<

ijoormaLizei s%otcconduc:i.;ic ;n,r cn.' &yi( c y t - i n t h e p r e v i o u s s e c t i o h , was a b o u t +6OV and + l l O V f o r 35W and 55W, r e s p e c t i v e l y . I t i s uot ivi t? od n : rgom tr..nperai!<ra .?or imdqes' filnc n s

c o n c l u d e d comoarina w i t h t h e s e d a t a t h a t

I .=u'urction o f b i a s v o l t a g e . t h e optimum s u b s t r a t e p o t e n t i a l w i t h r e s p e c t t o t h e plasma i s about -60V c o n s t a n t f o r b o t h t h e powers.

The most f a v o u r a b l e b i a s v o l t a g e f o r p h o t o c o n d u c t i v e p r o p e r t y does n o t a g r e e w i t h t h a t m i n i m i z i n g t h e SiH2 a b s o r p t i o n mode as can be found i n F i g s .

3

and

4 . Namelr, ^Fhe

f o l l o w i n g s t a t e m e n t m i g h t n o t a l w a y s be v a l i d ; t h e r a t i o a ( 2 0 0 0 crn-l)/a(2090 cm- ) ^{I S} a good measure o f t h e f i l m q u a l i t y f o r a s o l a r c e l l m a t e r i a l [ l 2 ] . I t w o u l d be imagined t h a t a p r o b a b l e e f f e c t o f i o n damage p l a y s a more dominant r o l e on d e t e r m i n i n g t h e p h o t o c o n d u c t i v e p r o p e r t y t h a n t h e l o c a l b o n d i n g manner o f hydrogen i n a - S i : H . O p t i c a l - e m i s s i o n - s p e c t r o s c o p y 1neasureti.ents.- I n o r d e r t o c l a r i f y t h e b a s i c plasma k i n e t i c s and s u r f a c e r e a c t i o n s e n c o u n t e r e d i n b i a s e d plasma d e p o s i t i o n , we have rneas- u r e d t h e o p t i c a l - e m i s s i o n - s p e c t r a (OES) from t h e s i l a n e plasma' as a f u n c t i o n o f Vb. The o p t i c a l - e m i s s i o n i n t e n s i t i e s o f t h e r e a c t i v e s p e c i e s SiH, H2 and H i n t h e p o s i t i v e column o f plasma were n o t a f f e c t e d by Vb. On t h e o t h e r hand, t h o s e j u s t above t h e sub- s t r a t e were s t r o n g l y i n f u l e n c e d by Vb. F i g u r e 5 shows t h e i n t e n s i t y r a t i o o f r a d i c a l s SiH(413nm). H2(493nm) and HB(486nm) as a f u n c t i o n o f Vb. A l l t h e r a t i o s [ ~ i H l / [ H l ,

[ s ~ H ] / [ H ~ ] and [ H ] / [ H 2 ] have t h e extremes n e a r Vb 3

-

=O; i n c r e a s i n g t h e a b s o l u t e v a l u e o f b i a s v o l t a g e

-

6 O W l l c m causes t h e r a t i o o f [ s ~ H ] / [ H ] and [ s ~ H ] / ( H ~ ] t o 250 "C d e c r e a s e a p p r e c i a b l y , w h i l e a s m a l l i n c r e a s e i s

5

n o t e d i n t h a t o f [ H I / [ H Z ] . These b i a s v o l t a g e iSi H31fH3 dependences o f t h e i n t e n s i t y r a t i o a r e s i m i l a r t o

t h a t o f t h e e l e c t r i c a l and p h o t o c o n d u c t i v e p r o p e r -

E

t i e s o f P-doped (as can be seen i n t h e f o l l o w i n g s e c t i o n ) and undoped a - S i : H f i l m s . T h i s i m p l i e s t h a t i n c r e a s i n g t h e r a t i o o f [ S i H ] / [ H ] , [ S i H I / [ t i 2 ] G a n d / o r d e c r e a s i n g t h a t o f [t4]/[H2] a r e f a v o r a b l e 3

E

-

f o r t h e p h o t o c o n d u c t i v e and e l e c t r i c a l p r o p e r t i e s

o f undoped and P-doped f i l m s . I n c o n t r a s t t h e [14Y[H21

m o n o t o n i c a l b i a s dependence o f t h e r a t i o d-

~(2090cm-l)/o(ZOOOc.-I) i s n o t c o n s i s t e n t w i t h t h e o

l -

t r e n d o f r e s u l t s i n OES measurements. So i t can be

.z

c o n c l u d e d t h a t t h e c o n c e p t " d e c r e a s i n g t h e r a t i o

o f [ s ~ H ] / [ H ] o r i n c r e a s i n g t h a t o f [ H ] / [ t i 2 ] i n 0 -

H 4 8 6 n m

-

H 2 : 493 nln

. S i H ,

4 1 3 n m

I I I I

plasma causes a h i g h c o n c e n t r a t i o n o f SiH2 mode i n

d o p o s i t e d f i l m s " [ l 3 ] i s n o t v a l i d i n g e n e r a l .

-

100 0 100 B i a s Voltage ( V )

~ i a s e f f e c t s on i m p u r i t y do-- S i n c e hydrogen pis.5 palio ^cfo ? t i c n ~ - e m i s s i o n i r , t e n s i c i s s i n c o r p o r a t i o n manner was c o n f i r m e d t o be s t r o n g l y

a f f e c t e d by b i a s , i t might be r a t h e r n a t u r a l to of Si!!, 3,. CX'! Ba Line i n S ' u / ? _"'4 gZcw d i s -

' 2 zicarge as a .?xfction o f bias v o l l c g e .

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C4-634 .;OUENAI.

DE

PHYSIQUE

-

c o n s i d e r t h a t t h e i n c o r p o r a t i o n manner o f t h e im- p u r i t y atoms i s a l s o c o r r e l a t e d w i t h Vb. Based on t h i s s p e c u l a t i o n , we have c a r r i e d o u t a s e r i e s o f e x p e r i m e n t a l i n v e s t i g a t i o n s on t h e e l e c t r i c a l and o p t o e l e c t r o n i c p r o p e r t i e s o f doped a - S i : H f i l m s d e p o s i t e d under t h e e x i s t e n c e o f Vb. F i g u r e

6

d e m o n s t r a t e s b i a s f u n c t i o n a l d a t a o f ud and npr

5

f o r P and 6-doped a - S i : H f i l m s d e p o s i t e d w i t h

1 ⁸

gaseous r a t i o o f PHj/SiHz,=O.i vo1.0 and B2H6/SiHq=

j10''G 0.2 v o l . % , r e s p e c t i v e l y . As seen i n t h e f i g u r e , ud

u

- &

and nu^ o f P-doped f i l m s have t h e e x t r e m e a t a b o u t

0-+50V b i a s e d c o n d i t i o n w h i c h wa5 s i m i l a r t r e n d t o u t h e r e s u l t s o f undoped one. Vhi l e , r h o s e o f €5-doped

2

one e x h i b i t r ~ ~ o n o t o n i c a l change w i t h Vb. E s p e c i a l l y , t h e d a r k c o n d u c t i v i t y d r a s t i c a l l y i n c r e a s e s w i t h p o s i t i v e b i a s v o l t a g e above +5OV. There may be t h r e e f a c t o r s r e s p o n s i b l e f o r t h e enhancement o f - 1 0 G 3 103 od

,

t h a t i s , i n c r e a s e o f b o r o n atoms i n c l u d e d i n

BIAS V O L T A G E ~ V )

f i l m s , improvement o f t h e p r o b a b i l i t y t h a t boron atoms a r e i n c o r p o r a t e d i n an e l e c t r i ; a l l y a c t i v e F i p . 6 No.maLized p b t o c m d u c t i u i t ~ rlur and

s u b s t i t u t i o n a l s i t e ( = d o ~ i n o . . - e f f i c i e n c v ) and dark co?lrcct-lvit ³

.

a t rnon ten?srz:Ar,e ;^or reduct ion o f gap s t a t e dens i t y w h i c h a~ lows t h e boron dcrsd n l d pJ!ospiior*us h z 7 e 2 a-St::/ as a Fermi l e v e l t o eas i l y s h i f t toward e i t h e r e x t e n d e d /unction o f bins v o i t q e . band. I n t h e c o u r s e o f t h e p r e l i m i n a r y s t u d y o f

I M A and E S R , i t has been deduced t h a t t h e f o r m e r two i n t e r p r e t a t i o n s a r e more a c c e p t a b l e . These f a c t s mean t h a t t h e s u r f a c e p o t e n t i a l a t t h e s u b s t r a t e has a s i g n i f i c a n t i n f l u e n c e n o t o n l y on t h e b o r o n i n c l u d i n g e f f i c i e n c y b u t a l s o on t h e d o p i n g e f f i c i e n c y r e l a t e d t o t h e i m p u r i t y i n c o r p o r a t i o n manner i n a - S i : H f i l m s .

Summary.-

A s e r i e s o f e x p e r i m e n t a l i n v e s t i g a t i o n s on t h e mechanism o f plasma decomposi- t i o n and amorphous S i d e p o s i t i o n have been made by t h e c r o s s f i e l d f u r n a c e . The r e s u l t can be sumnarized as t h e f o l l o w i n g : f i ) E f f e c t s o f p r e p a r a t i o n c o n d i t i o n on t h e f i l m p r o p e r t y s h o u l d be d e v i d e d i n t o t h r e e s e p a r a t e p r o c e s s e s o f t h e d e p o s i t i o n mechanism, t h a t i s , a ) p l a s ~ n a d e c o m p o s i t i o n o f s o u r c e gases ( d i r e c t l y a f f e c t e d by gas p r e s s u r e , d i s c h a r g e power d e n s i t y and k i n d o f s o u r c e g a s e s ) , b) d i f f u s i o n o f i o n i z e d and n e u t r a l s p e c i e s t o t h e v i c i n i t y o f s u b s t r a t e , and c ) d e p o s i t i o n o f s p e c i e s on t o s u b s t r a t e

(

a f f e c t e d by k i n e t i c e n e r g y and e x c i t a t i o n e n e r g y o f s p e c i e s v e r y s e v c r l y ) . The sub- s t r a t e p o t e n t i a l does c o r r e l a t e w i t h t h e p r o c e s s e s b) a n d / o r c ) . The d e p o s i t i o n p a r a - m e t e r s such as plasma d i s c h a r g e power and gass p r e s s u r e a f f e c t a l l t h e p r o c e s s e s a ) , b) and c ) t h r o u g h c h a n g i n g t h e s u b s t r a t e p o t e n t i a l o r o t h e r f a c t o r s . ( i i ) As t h e e x p e r i m e n t a l c o n d i t i o n , s u r f a c e p o t e n t i a l a t t h e s u b s t r a t e , d i s t a n c e between p o s i t i v e column and s u b s t r a t e , and s u b s t r a t e t e m p e r a t u r e d e t e r m i n e t h e c o m p i l i n g manner o f hydrogen and i m p u r i t y atoms i n t o t h e aniorphous n e t w o r k , c o n s e q u e n t l y , d e c i d e t h e f i l m p r o p e r t y . ( i i i ) To have t h e c o n t r o l l a b i l i t i e s on t h e above t h r e e s e p a r a t e p r o c e s s e s , t h e c r o s s f i e l d plasma d e p o s i t i o n method i s one o f t h e most c o n v e n i e n t d e p o s i t i o n t e c h n o l o g y .

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