@
0 ¹ Å c Ü R ¹ Å £ ;; c ¥ ¹ Å ¹ ÅM W _ Ë Ò Þ (Dielectrophoresis ; DEP) U ê s0 n É ù p § T
Ó Þ X ¢ GaN x ¢Ñ ÷T # a8 ý X N Ëc Ç õ m Í ¹ Å4 ÇÊ Ý² O U ' [8 ý Ö « Ó Þ
T
û B ÷ 7 B · »? ý ¡ · T ç ¡ - ! H ∗
· ¡ ¤ @ / < Æ § ì ø Í ¸^ õ < Æl Õ ü t < Æõ , ì ø Í ¸^ Ó ü t$ í ½ ¨ è, Å Ò 561-756 (2006¸ 9 Z 4 7{ 9 ~ Ã Î6 £ §, þ j7 á x : r 2006¸ 11 Z 4 6{ 9 ~ Ã Î6 £ §)
:
r 7 Hë H \ " f H ¸ü <s # Q\ ¦ & ñ § > = r ~ ´ à º e H ~ ½ ÓZ O × æ _ Ä » l % ò 1 l x (dielectrophoresis ; DEP) ~ ½ ÓZ O ` ¦ ½ ¨ % i Ü ¼ 9 s \ ¦ s 6 x # { 9 " é ¶& h GaN ¸ü <s # Q\ ¦ p o J ) a F G (Ti/Au)
\
& ñ § > =r ( . GaN ¸ü <s # Q_ & ñ § > =\ % ò ¾ Ó` ¦ p u H Ó ü t o & h כ ¹ è H AC · ú õ Å Ò Ã ºe ` ¦ S X
½ + É Ã º e % 3 Ü ¼ 9 ¢ ¸ô Ç AC · ú õ Å Ò Ã º\ " f GaN ¸ü <s # Q J ) a F G \ & ñ § > = ) a ³ ð
+ þ AI _ ¸_ þ v ¸ ² ú f ` ¦ · ú Ã º e % 3 . AC · ú s 7 £ x ½ + ÉÃ º2 ¤ (1 ∼ 20 V
p−p) GaN ¸ü <s # Q
p
o J ) a F G \ & ñ § > =| ¨ c S X Ò ¦ É r 7 £ x % i . 10 kHz, 20 MHz ¿ º â Ä º ¸¿ º GaN ¸ü <s # Q
J
) a F G \ & ñ § > = ) a S X Ò ¦ É r þ j@ / 80 % s © ` ¦ f ` ¦ z ´+ « >& h Ü ¼ Ð S X % i . s Qô Ç DEP ~ ½ ÓZ O Ü
¼ Ð & ñ § > =ô Ç GaN ¸ü <s # Q\ ¦ s 6 x # back-gate > ´ òõ à Ô ½ t Û ¼' ½ ¨ ¸\ ¦ ½ ¨ & ³ % i Ü ¼ 9 l > r _
c o èÕ ªA x ¸¹ ¡ § \ O s ç ß é ß ¦ < H~ 1 > GaN ¸ü <s # Q_ l & h : £ ¤$ í x 9 è _ : £ ¤
$ í
` ¦ 8 £ ¤& ñ ½ + É Ã º e 6 £ §` ¦ S X % i .
PACS numbers: 72.20.-I, 72.80.Ey
Keywords: Ä » l % ò 1 l x, | 9 o° ú µ ¢ § ¸ , > ´ òõ à Ô ½ t Û ¼'
I. " e  ] Ø
&
³F > h> h_ ¸ è \ ¦ @ / & h Ü ¼ Ð | 9 & h o r v ¦ F
g è x 9 è \ 6 £ x6 x l 0 AK " f H s > h> h_
¸ è [ þ t` ¦ ¸ ú ¸ ½ + É Ã º e Ü ¼ 9 & ñ § > =r ~ ´ Ã º e H l Õ
ü
t s ] X @ /& h Ü ¼ Ð 9 כ ¹ [1]. ' & h Ü ¼ Ð Ð ¦ ) a l Õ
ü
t \ H DEP ~ ½ ÓZ O , s ß ¼ ÐÄ »^ G V , ~ ½ ÓZ O (microflu- idic channel), Langmuir-Blodgett ~ ½ ÓZ O 1 p x s e [1-3].
s
× æ \ " f DEP ~ ½ ÓZ O É r : r ¸È ÓÚ Ô (carbon nanotube
; CNT), F K5 Å q ¸ü <s # Q, ì ø Í ¸^ ¸ü <s # Q, ¸ { 9
[ þ t` ¦ ¸ ¦ & ñ § > =r ~ ´ Ã º e H ¿ ËÒ 6 x ô Ç ~ ½ ÓZ O × æ \
Ð s \ H Ò q t_ < Æ ì r \ " f ´ ú §s 6 x ÷ &# Q M ® o Ü ¼ 9
&
³F H o < Æ x 9 ì ø Í ¸^ ì r \ 6 x H â ¾ Ós e [4- 7]. þ j H \ H DEP ~ ½ ÓZ O ` ¦ s 6 x # ZnO ¸6 \ à Ô (ZnO nanobelts)\ ¦ J ) a F G \ q @ /g A& h Ü ¼ Ð & ñ § > =r & ® é à
Ôv s ¸× ¼\ ¦ ½ ¨ & ³ % i [7]. t ë ß @ / Òì r _ '
½ ¨_ ? /6 x` ¦ Ð DEP ~ ½ ÓZ O ` ¦ s 6 x # ì ø Í ¸^
¸ü <s # Q : r ¸È ÓÚ Ô\ ¦ > h> h_ ¢ ¸ H µ 1 Ï Ð & ñ § > = r
v H כ \ ë ß í& h s ´ ú Æ Ò# Q4 R e % 3 . ¢ ¸ô Ç & ³F t GaN ¸ü <s # Q\ ¦ DEP ~ ½ ÓZ O ` ¦ s 6 x # & ñ § > =r v H
∗
E-mail: sk˙[email protected]
כ
\ @ /K ^ > & h Ü ¼ Ð ½ ¨ s À Ò# Qt t · ú § ¤ .
"
f GaN ¸ü <s # Q\ ¦ s 6 x # @ / & h _ è \ ¦ ë ß [ þ t
¦ F g è x 9 è \ 6 £ x6 x` ¦ l 0 AK " f H GaN
¸ü <s # Q DEP ~ ½ ÓZ O \ _ K & ñ § > =| ¨ c S X Ò ¦ õ F $ í \
@
/ # ^ > & h ½ ¨ 9 כ ¹ . : r ½ ¨\ " f H J s
+ þ A$ í ) a F G \ DEP ~ ½ ÓZ O ` ¦ s 6 x # GaN ¸ü <s
#
Q\ ¦ AC · ú õ Å Ò Ã º\ & ñ § > =r v H / B N& ñ ` ¦ þ j& h
or ( . ¢ ¸ô Ç % 6 £ § Ü ¼ Ð ì ø Í ¸^ ¸ü <s # Q_ l & h
: £ ¤$ í ` ¦ DEP ~ ½ ÓZ O ` ¦ s 6 x # ~ 1 > 8 £ ¤& ñ ½ + É Ã º e H
~
½ ÓZ O ` ¦ è> h % i . Æ Ò& h Ü ¼ Ð GaN ¸ü <s # Q_ F
«
Ñ& h : £ ¤$ í \ @ /K " f ¸ 7 H _ % i .
II. ÷ m Ç ] M ö
: r ½ ¨\ 6 x ) a GaN ¸ü <s # Q Ò re ¦ É r horizontal hot-wall chemical vapor deposition (CVD) ~ ½ ÓZ O Ü ¼ Ð $ í
© ) a ¸ü <s # Qs . $ í © \ 6 x ) a l ó ø Í É r s # Q c-plane l ó ø Ís 9 800 ∼ 1000
◦C \ " f VLS (vapor-liquid- solid) $ í © ` ¦ 0 AK sputter\ ¦ s 6 x # Ni 8 ú ¤ B \ ¦ 2
&
ñ ¸ 7 £ x à Ìr ( . Ga x 9 N èÛ ¼ Ð H Ga F K5 Å q õ NH3
-46-
Û
¼\ ¦ 6 x % i . DEP ~ ½ ÓZ O ` ¦ à º' l 0 AK IPA (iso- propyl alcohol) 10 mL \ GaN ¸ü <s # Q\ ¦ ì r í ß r (
¦ n-type [100] z ´o B H l ó ø Í 0 A\ í Ðo èÕ ªA x l Õ ü t
`
¦ s 6 x # p o Ti/Au (50/100 ) F G` ¦ + þ A$ í % i
. ô Ç > h_ Ò re ¦ \ p o J ) a F G _ Ã º H 200 > hs 9, y y _ F G s _ o H 4 µm s . í Ðo èÕ ª A
x Ð J ) a F G \ s ß ¼ Ðx & Ï @` ¦ s 6 x # GaN
¸ü <s # Q ì r í ß ÷ &# Q e H IPA 6 xÓ o 3 uL\ ¦ b # Qä ¼§ 4
. Õ ª 6 £ § + þ A$ í ) a F G \ AC · ú ` ¦ # QÅ Ò# Q 6 xÓ o s
\ ¦ M : t l 2 ; Ê ê > ~ ½ ÓØ ¦ Å Ò & ³p â s
UV (ultraviolet) & ³p â ` ¦ s 6 x # F G s \ & ñ
§ >
= ) a GaN ¸ü <s # Q_ > hà º\ ¦ 8 £ ¤& ñ % i . : r ½ ¨\
"
f H & ñ § > = ) a GaN ¸ü <s # Q_ > hà º\ ¦ 200 > h_ F G _ Ã
º\ ´ ú Æ Ò# Q S X Ò ¦& h Ü ¼ Ð > í ß ` ¦ % i . # l \ 6 x ) a
&
ñ § > = ) a S X Ò ¦ _ _ p H DEP ~ ½ ÓZ O Ü ¼ Ð & ñ § > = ) a ¸ü <s
#
Q F G 0 A\ \ O & ñ § > =s ÷ &% 3 H t \ ¦ ³ ð & ³ô Ç . 7 £ ¤, 100 % _ _ p H 200 > h_ F G \ ¸¿ º ¸ü <s # Q & ñ
§ >
=÷ &% 3 6 £ §` ¦ _ p 9 ô Ç > h_ ¸ü <s # Q & ñ § > =s ÷ &
%
3 Ü ¼ & ñ § > =s ÷ &% 3 ¦ ó ø Íé ß % i . ¢ ¸ô Ç : r ½ ¨\ " f
H z ´+ « >\ 6 x ) a GaN ¸ü <s # Q_ l & h : £ ¤$ í ` ¦ 8
£ ¤& ñ l 0 AK back-gate + þ AI _ > ´ òõ à Ô ½ t Û ¼' ½ ¨
¸\ ¦ ] j # Õ ª[ þ t _ : £ ¤$ í ` ¦ 8 £ ¤& ñ % i . ] j ) a Ò re ¦ à
Ô ½ t Û ¼' _ l & h 8 £ ¤& ñ É r semiconductor parame- ter analyzer (HP4155) ) a probe station \ " f z ´r
% i Ü ¼ 9 8 £ ¤& ñ ½ + É M :_ : r ¸ H © : r` ¦ Ä »t % i .
III. + s ÇÊ Ý õ m Í À X Ø8 ý
Fig.1 _ (a) H Ga B j» 1 Ïõ NH3 Û ¼ì r 0 Al \ " f s
# Q l ó ø Í 0 A\ CVD ~ ½ ÓZ O Ü ¼ Ð ½ + Ë$ í ) a GaN ¸ü <s # Q _
& ³p â ` ¦ Ð# ï r . GaN ¸ü <s # Q
s # Q l ó ø Í\ ^ & h Ü ¼ Ð ¸ ú $ í © ô Ç כ ` ¦ S X ½ + É Ã º e
Ü ¼ 9 t 2 £ § É r 10-300 s 9 U ´s H à º \ " f à ºÑ þ
?
/ü @ s . ¦ì r K 0 p x È Òõ & ³p â õ РÒ' GaN
¸ü <s # Q H [001] » ¡ ¤ Ü ¼ Ð $ í © ÷ &% 3 Ü ¼ 9 wurtzite½ ¨ ¸ _
GaN ¸ü <s # Q\ ¦ S X ½ + É Ã º e % 3 . ¢ ¸ô Ç F g < Æ& h
ì r$ 3 l l × æ © : r photoluminescence (PL) Ð Â
Ò' GaN ¸ü <s # Q_ photoluminescence_ emission peak H 374 nm (3.32 eV) © H % \ " f ' a ¹ 1 Ï H d` ¦ S X
% i . Fig. 1_ (b) H DEP ~ ½ ÓZ O \ " f AC · ú ` ¦ K Å
Òl 0 AK function generatorü < probe-station` ¦ ô Ç
¸_ þ v s . Fig. 1 (c)\ " f H Si/SiO2 l ó ø Í 0 A\ í Ðo è Õ
ªA x \ ¦ s 6 x # p o J ) a 200 > h_ F G` ¦ Ò
re ¦` ¦ S X ½ + É Ã º e . : r z ´+ « >\ " f H K Å Ò H AC
Fig. 1. (a) A SEM image of GaN nanowires grown on a substrate. (b) A image of the dielectrophoresis measure- ment set-up with (c) an enlarged image of the electrodes.
· ú õ Å Ò Ã º\ " f p o J ) a F G \ & ñ § > =÷ & H
&
ñ ¸\ ¦ S X Ò ¦& h Ü ¼ Ð · ú Ð ¦ Ò re ¦ \ GaN ¸ü <s # Q
&
ñ § > = ) a + þ AI _ ¸_ þ v \ @ /K " f · ú Ð H כ \ í& h ` ¦ ´ ú Æ
Ò% 3 . s Qô Ç ¸| ` ¦ ´ ú Æ Òl 0 AK : r ½ ¨\ " f H
)
a Å Ò Ã º y y 10 kHz, 20 MHz s ¦ AC · ú s 1, 5, 10, 15, 20 V
p−p{ 9 M :_ Ò re ¦` ¦ ï r q # z ´+ « >` ¦ z ´r
%
i . Fig. 2_ (a)\ " f y y _ Å Ò Ã ºü < AC · ú \
É r GaN ¸ü <s # Q[ þ t s F G 0 A\ & ñ § > = ) a S X Ò ¦` ¦
?
/# QÅ Ò ¦ e Ü ¼ 9 Õ ªa Ë >\ " f · ú Ã º e 1 p w s 8 Z } É r AC
· ú
` ¦ K Å Ò GaN ¸ü <s # Q & ñ § > =| ¨ c S X Ò ¦ s 8
¹
¡
¤ 8 & f ` ¦ · ú à º e . s z ´+ « >\ " f GaN ¸ü <s # Q
Fig. 2. (a) The yield rate of the aligned GaN nanowires in the gap over the entire array as a function of the ac electric field at the frequencies of 10 kHz and 20 MHz.
The SEM images of the aligned GaN nanowires in the gap over the entire array for ac 1 V
p−p, 5 V
p−p, 10 V
p−p, 15 V
p−p, and 20 V
p−pat the frequencies of (b) 10 kHz and (c) 20 MHz. The solid-line denotes the fitting line as a visual guide.
DEP j Ë µ ? /\ " f # Qb G> ¹ ¡ §f s H t · ú l 0 AK " f H · ú
9 ç H{ 9 ô Ç " é ¶: x+ þ Aõ | ¸ü <s # Q\ AC · ú ` ¦
K
ï r ¸4 S q` ¦ ¦ 9 # [ O " î s 0 p x . DEP j Ë µ É r 6 £ § õ
° ú s Å Ò# Q [5].
F ~
DEF= πr
2l
2 ε
mK(ω) ~ ∆( ~ E
rms2) (1) K(ω) ≡ Re[ ε
∗n− ε
∗mε
∗m], ε
∗≡ ε − i σ ω
#
l " f E
rms~ l © _ root mean square° ú כs ¦ K(ω) H Clausius-Mossotti s 9 ε
m É r B | 9 _ Ä » © Ã ºs .
¢
¸ô Ç r õ l É r GaN ¸ü <s # Q_ ì ø Ít 2 £ § õ U ´s \ ¦
?
/ 9 d (1)\ " f (*) ³ ðr H Ä » © à º_ 4 ¤ èà º ½ Ó` ¦
· p . Fig. 2 (a)\ " f DEP j Ë µ É r l © _ l Ö ¦ l \ q Y
V Ù ¼ Ð 8 Z } É r AC · ú s ÷ &# Qt GaN ¸ü <
s
# Q & ñ § > =| ¨ c S X Ò ¦ ¸ Z } f ` ¦ · ú Ã º e . Ä ºo H Å Ò
à º 10 kHz, 20 MHz, AC · ú 15 V
p−p, 20 V
p−p\ " f
&
ñ § > =| ¨ c S X Ò ¦ s þ j@ / 80 % & ñ ¸ t H d` ¦ · ú Ã º e % 3 .
Fig. 2 (b) H Å Ò Ã º 10 kHz, 20 MHz { 9 M : AC · ú s
1 V
p−p\ " f 20 V
p−p Ð 7 £ x < Ê\ & ñ § > =÷ &# Qt H GaN ¸ü <s # Q_ à º 7 £ x H ¸_ þ v` ¦ · p
&
³p â s . s ° ú É r õ H AC · ú _ ß ¼l \ ¦ ¸ ] X
# p o J ) a F G s \ & ñ § > =÷ & H GaN ¸
Fig. 3. The distribution of the yield rate for aligned GaN nanowires in the gap over the entire 200 electrode array with (a) 10 V
p−pand (b) 15 V
p−pat the frequencies of 10 kHz and 20 MHz.
ü
<s # Q_ Ã º\ ¦ ¸] X ½ + É Ã º e H > p w s . " f AC
· ú
` ¦ & h ] X > ¸] X ` ¦ # # Q t è G ' p" f\ 6 £ x 6
x` ¦ ½ + É Ã º e . ¢ ¸ô Ç d (1) \ " f Ð K Å Ò H Å Ò Ã
º ¸ GaN ¸ü <s # Q & ñ § > =÷ & H X < ¦ 9K ½ + É Ó ü t o
&
h כ ¹ è . # l " f @ / & h è ´ ú § É r ª _ è \ ¦ % 3 l
0 AK " f H ¸ü <s # Q & ñ § > =÷ & H S X Ò ¦ _ ì r íü < F
$ í s # QÖ ¼ & ñ ¸ e # Q ô Ç . Õ ª QÙ ¼ Ð Ä ºo H ¿ º t
Å Ò Ã º\ @ /K " f & ñ § > =÷ & H S X Ò ¦ õ ³ ð + þ AI _ ¸_ þ v
\
@ /K " f z ´+ « >` ¦ % i . z ´+ « >\ 6 x ) a Ò re ¦ É r 10 > hm 1 [ jà Ô Ð 8 ú x 4 [ jà Ô_ Ò re ¦ s 6 x ÷ &% 3 . y y ô Ç [ jà Ôm
É r ¸| Ü ¼ Ð Å Ò Ã ºü < AC · ú ` ¦ K Å Ò% 3 . % 6 £ §
¿
º [ jà Ô H AC · ú 10 V
p−p{ 9 M : Qt ¿ º [ jà Ô H 15 V
p−p{ 9 M : y y 10 kHz, 20 MHz_ Å Ò Ã º\ " f z ´+ « >` ¦
' % i . Fig. 3 (a), (b) H 10 kHz, 20 MHz{ 9 M : AC
· ú 10 V
p−p, 15 V
p−p\ " f_ GaN ¸ü <s # Q 200> h _
p o J ) a F G \ & ñ § > =| ¨ c S X Ò ¦` ¦ ? /# QÅ Ò ¦ e
Fig. 4. Low-magnitude SEM images of the electrodes subjected to 10 V
p−pat the frequency of (a) 10 kHz and (b) 20 MHz and for the 15 V
p−pat the frequencies of (c) 10 kHz and (d) 20 MHz.
Ü
¼ 9 ¨ î ç H& h Ü ¼ Ð Å Ò Ã º 10 kHz{ 9 M : & ñ § > =| ¨ c S X Ò ¦ s 20 MHz{ 9 M :_ & ñ § > =| ¨ c S X Ò ¦ Ð 2C & ñ ¸ Z }6 £ §` ¦ · ú Ã
º e . DEP j Ë µ\ " f Å Ò Ã º\ " f K(ω)_ ° ú כ ß ¼l
² ú t l M :ë H s . Fig. 4 H 10 kHz, 20 MHz y y _ Å
Ò Ã º\ " f AC · ú (10 V
p−p, 15 V
p−p) \ É r ³ ð + þ
AI _ ¸_ þ v` ¦ Ð# Å Ò ¦ e H Å Ò & ³p â s .
± ú
É r Å Ò Ã º (= 10kHz) { 9 M : GaN ¸ü <s # Q F G
s _ © o \ ¸ ú & ñ § > =÷ &# Q e H ¸_ þ v` ¦ S X ½ + É Ã º e
. Z } É r Å Ò Ã º (f = 20 MHz) { 9 â Ä º\ H & h É r à º_ GaN ¸ü <s # Q ¢ ¸ H { 9 [ þ t ë ß s ' a ¹ 1 Ï H d` ¦ · ú à º e .
s
° ú É r õ Ð K & ñ § > =÷ & H S X Ò ¦ õ ³ ð + þ AI _ ¸_ þ v
É r ÷ & H Å Ò Ã º\ B Ä º _ > r < Ê` ¦ · ú Ã º e . s ° ú É r
õ \ ¦ s K l 0 AK " f H d (1)\ " f B | 9 õ ¸ü <s
#
Q_ conductivityü < y Å Ò Ã º\ @ /K É r ° ú כ` ¦ t H K(ω) \ @ /K " f s K \ ¦ K ô Ç . B | 9 s IPAs ¦ GaN
¸ü <s # Q{ 9 M : _ s : r ° ú כ É r Å Ò Ã º 1 kHz ∼ 80 MHz\
"
f1.7 × 10
7< K(ω/2π) < 1.0 s . GaN ¸ü <s # Qü <
B
| 9 _ conductivityü < Ä » © Ã º H y y σ
n= 104 S/m [1], ε
n= 12.2 ε
0[8], σ
m= 6 × 10
−6S/m, ε
m= 18.3 ε
0[9] s . z ´+ « >& h Ü ¼ Ð ½ ¨ô Ç GaN ¸ü <s # Q_ K(ω)° ú כ
É r 10 kHz, 20 MHz ¿ º Å Ò Ã º\ " f ¸¿ º ª _ K(ω) ° ú כ` ¦ (positive DEP) ° ú H . Õ ª QÙ ¼ Ð Fig. 4\ " f ^ ¦ à º e 1 p w s
p o J ) a F G _ = å Q Â Òì r \ " f & ñ § > = ) a . Fig. 3_ (a), (b) \ " f K ï r Å Ò Ã º 10 kHz{ 9 M : GaN ¸ ü
<s # Q J ) a F G \ & ñ § > =| ¨ c S X Ò ¦ s 20 MHz{ 9 M : Ð
_ ¿ º C & ñ ¸e ` ¦ · ú Ã º e . s Qô Ç & ³ © É r DEP j Ë
µ\ " f 10 kHz{ 9 M : K(ω)_ ° ú כs 20 MHz{ 9 M :_ ° ú כ Ð
107C & ñ ¸ ß ¼l M :ë H s . כ ¹ 10 kHz, 20 MHz
¿
º t Å Ò Ã º ¸¿ º\ " f GaN ¸ü <s # Q J ) a
Fig. 5. A schematic diagram of the process for fabri- cation of GaN nanowire back-gate field effect transistor (FET) structure which were formed by dielectrophoresis on n-Si (100) wafer.
Fig. 6. Current-voltage characteristics of the many GaN nanowire devices contacted with Ti/Au electrodes for the different back gating from -40 V to 40 V. The Inset is a SEM image of a two-terminal GaN nanowire device.
F
G _ © o  Òì r \ " f ¸ ú ¸s ¦ & ñ § > =s ) a . Fig. 3, 4 \ " f 10 V
p−p, 15 V
p−p{ 9 M : & ñ § > =| ¨ c S X Ò ¦ õ ³ ð + þ AI
¸_ þ v _ q 5 p w ô Ç õ \ ¦ ? /# QÅ Ò ¦ e . DEP ~ ½ ÓZ O Ü ¼
Ð & ñ § > =ô Ç GaN ¸ü <s # Q_ l & h : £ ¤$ í ` ¦ ~ 1 ¦ ç ß
¼
# > 8 £ ¤& ñ l 0 AK " f back-gate > ´ òõ à Ô ½ t Û ¼'
½
¨ ¸\ ¦ ½ ¨ & ³ % i Ü ¼ 9 3-probe system` ¦ s 6 x # 8 £ ¤& ñ
`
¦ % i . Fig. 5\ " f J ) a F G \ DEP ~ ½ ÓZ O ` ¦ s 6 x
# & ñ § > = ) a GaN ¸ü <s # Q_ back-gate > ´ òõ à Ô ½ t
Û ¼' ½ ¨ ¸\ ¦ ½ ¨ & ³ô Ç ¸d ¸\ ¦ ^ ¦ Ã º e . Fig. 6\ " f
èÛ ¼-× ¼Y U · ú s -10 V ∼ 10 V{ 9 M : > s à Ô · ú ` ¦ -40 V ∼ 40 V t 10 V é ß > Ð GaN ¸ü <s # Q & ñ § > =
)
a Ò re ¦ _ l & h : £ ¤$ í ` ¦ 8 £ ¤& ñ % i . GaN ¸ü <s
#
Q_ conductance 0 Ð H > s à Ô · ú \ " f H 7 £ x
¦ 0 Ð É r > s à Ô · ú \ " f H y è % i . s õ
\ ¦ : x K z ´+ « >\ 6 x ) a GaN ¸ü <s # Q H à ºH o
#
Q n-type ì ø Í ¸^ e ` ¦ · ú Ã º e % 3 . ´ ú § É r bulk GaN \ @ /ô Ç ' ½ ¨ õ \ Ø Ô ¸i ç ` ¦ Ð t
· ú
§ ¸ GaNs n-typeÜ ¼ Ð $ í © s ÷ & H X < s H / B N& ñ ` ¦
H 1 l x î ß | 9 è 4 R ¢ ¸ H í ß è B j» 1 Ïs Ô ¦ í
HÓ ü t Ð 6 x` ¦ ½ + É Ã º e l M :ë H s [1,2]. : r ½ ¨\ " f æ ¼
¸ü <s # Q_ l & h : £ ¤$ í 8 £ ¤& ñ ~ ½ ÓZ O É r c o
èÕ ªA x / B N& ñ \ O s ~ 1 ¦ ç ß ¼ # > 8 £ ¤& ñ ½ + É Ã º e H ´ òõ
&
h ~ ½ ÓZ O × æ e ` ¦ · ú Ã º e .
IV. + s Ç Â ] Ø
: r 7 Hë H \ " f H GaN ¸ü <s # Q DEP ~ ½ ÓZ O Ü ¼ Ð J
) a F G \ & ñ § > =÷ & H S X Ò ¦ õ & ñ § > =÷ & H Ò re ¦ ³ ð + þ AI _
¸_ þ v É r F G \ K Å Ò H AC · ú ÷ r ë ß m Å Ò
à º_ % ò ¾ Ó ¸ ~ à ΠH H כ ` ¦ S X ½ + É Ã º e % 3 ¦ Z } É r AC · ú ` ¦ # QÅ Ò GaN ¸ü <s # Q & ñ § > =÷ & H S X Ò ¦ s
Z } t H כ ` ¦ · ú Ã º e % 3 . s H DEP j Ë µ_ ß ¼l
l © [ jl _ l Ö ¦ l \ q Y V l M :ë H s . Õ ªo ¦ GaN ¸ü <s # Q J ) a F G \ & ñ § > =| ¨ c S X Ò ¦ É r Å Ò Ã
º 10 kHz { 9 M : 20 MHz { 9 M : Ð 2C & ñ ¸ Z } ¤ ¦ s
& ³ © É r DEP j Ë µ y y _ Å Ò Ã º\ @ /ô Ç K(ω)° ú כ` ¦ q
§K Ð [ O " î s ) a . : r ½ ¨\ ¦ : x # ì ø Í ¸^ ¸ ü
<s # Q\ @ /K " f ¸ DEP s : r s { 9 u H d` ¦ · ú Ã º e % 3 .
¢
¸ô Ç DEP ~ ½ ÓZ O Ü ¼ Ð J ) a F G \ & ñ § > = ) a GaN
¸ü <s # Q_ l & h : £ ¤$ í ` ¦ 8 £ ¤& ñ l 0 AK back- gate > ´ òõ à Ô ½ t Û ¼' ½ ¨ ¸\ ¦ ½ ¨ & ³ % i ¦ l & h 8
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Gallium Nitride Nanowire Alignment Using Dielectrophoresis and Its Application to Field-Effect Transistors
Seung-Yong Lee, Tae-Hong Kim and Sang-Kwon Lee
∗Department of Semiconductor Science and Technology, SPRC, Chonbuk National University, Jeonju 561-756 (Received 7 September 2006, in final form 6 November 2006)
We report a systematical investigation of the ac dielectrophoresis (DEP) force of the n-type gallium-nitride nanowires (GaN NWs) across patterned Ti / Au electrodes for various types of the DEP force and the frequency. We observed that the ability of the alignment strongly depended on the magnitude of the ac electric field and frequency. For a higher ac peak-to-peak electric field (up to 20Vp-p), the GaN nanowires had a better alignment across the patterned Ti / Au electrodes with a high yield rate of 80 % over the entire array (200) in the chip at 10 kHz and 20 MHz. We also discuss the electrical properties of the aligned GaN nanowires in the gap with a gate-modulated current-voltage characterization.
PACS numbers: 72.20.-I, 72.80.Ey
Keywords: Dielectrophoresis (DEP), GaN nanowire, Field-effect transistor
∗
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