Contact resistance plays an important role in amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). In this paper, the surface potential distributions along the channel have been measured by using Kelvin probe force microscopy (KPFM) on operating a-IGZO TFTs, and sharp potential drops at the edges of source and drain were observed. The source and drain contact resistances can be extracted by dividing sharp potential drops with the corresponding drain to source current. It is found that the contact resistances could not be neglected compared with the whole channel resistances in the a-IGZO TFT, and the contact resistances decrease remarkably with increasing gate biased voltage. Our results suggest that the contact resistances can be controlled by tuning the gate biased voltage. Moreover, a transition from gradual channel approximation to space charge region was observed through the surface potential map directly when TFT operating from linear regime to saturation regime.

1.
M.
Kim
,
J. H.
Jeong
,
H. J.
Lee
,
T. K.
Ahn
,
H. S.
Shin
,
J. S.
Park
,
J. K.
Jeong
,
Y. G.
Mo
, and
H. D.
Kim
,
Appl. Phys. Lett.
90
(
21
),
212114
(
2007
).
2.
H. H.
Hsieh
,
T. T.
Tsai
,
C. Y.
Chang
,
H.-H.
Wang
,
J.-Y.
Huang
,
S.-F.
Hsu
,
Y.-C.
Wu
,
T.-C.
Tsai
,
C. S.
Chuang
,
L.-H.
Chuang
, and
Y.-H.
Lin
,
SID Symp. Dig. Tech. Pap.
41
(
1
),
140
143
(
2010
).
3.
T.
Matsuo
,
S.
Mori
,
A.
Ban
, and
A.
Imaya
,
SID Symp. Dig. Tech. Pap.
45
(
1
),
83
86
(
2014
).
4.
E.
Fortunato
,
P.
Barquinha
, and
R.
Martins
,
Adv. Mater.
24
,
2945
(
2012
).
5.
K.
Nomura
,
H.
Ohta
,
A.
Takagi
,
T.
Kamiya
,
M.
Hirano
, and
H.
Hosono
,
Nature
432
,
488
(
2004
).
6.
K.
Nomura
,
H.
Ohta
,
K.
Ueda
,
T.
Kamiya
,
M.
Hirano
, and
H.
Hosono
,
Science
300
,
1269
(
2003
).
7.
T. J.
Richards
and
H.
Sirringhaus
,
J. Appl. Phys.
102
,
094510
(
2007
).
8.
P. V.
Necliudov
,
M. S.
Shur
,
D. J.
Guundlach
, and
T. N.
Jackson
,
Solid-State Electron.
47
,
259
(
2003
).
9.
H.
Wang
,
L.
Li
,
Z.
Ji
,
C.
Lu
,
J.
Guo
,
L.
Wang
, and
M.
Liu
,
IEEE Electron Device Lett.
34
(
1
),
69
71
(
2013
).
10.
W.
Wang
,
L.
Li
,
Z.
Ji
,
T.
Ye
,
N.
Lu
,
Z.
Li
,
D.
Li
, and
M.
Liu
,
IEEE Electron Device Lett.
34
(
10
),
1301
1303
(
2013
).
11.
K. P.
Puntambekar
,
P. V.
Pesavento
, and
C. D.
Frisbie
,
Appl. Phys. Lett.
83
,
5539
(
2003
).
12.
L.
Burgi
,
H.
Sirringhaus
, and
R. H.
Friend
,
Appl. Phys. Lett.
80
,
2913
(
2002
).
13.
J. A.
Nichols
,
D. J.
Gundlach
, and
T. N.
Jackson
,
Appl. Phys. Lett.
83
,
2366
(
2003
).
14.
V.
Coropceanu
,
J.
Cornil
,
D. A.
da Ailva Filho
,
Y.
Olivier
,
R.
Silbey
, and
J.-L.
Bredas
,
Chem. Rev.
107
,
926
(
2007
).
15.
S. F.
Nelson
,
Y.-Y.
Lin
,
D. J.
Gundlach
, and
T. N.
Jackson
,
Appl. Phys. Lett.
72
,
1854
(
1998
).
16.
H.
Klauk
,
G.
Schmid
,
W.
Radlik
,
W.
Weber
,
L.
Zhou
,
C. D.
Sheraw
,
J. A.
Nichols
, and
T. N.
Jackson
,
Solid-State Electron.
47
,
297
(
2003
).
17.
G. B.
Blanchet
,
C. R.
Fincher
,
M.
Lefenfeld
, and
J. A.
Rogers
,
Appl. Phys. Lett.
84
,
296
(
2004
).
18.
X.
Huang
,
C.
Wu
,
H.
Lu
,
F.
Ren
,
D.
Chen
,
R.
Jiang
,
R.
Zhang
,
Y.
Zheng
, and
Q.
Xu
,
Solid-State Electron.
86
,
41
(
2013
).
19.
J. K.
Jeong
,
H.-J.
Chung
,
Y.-G.
Mo
, and
H. D.
Kim
,
J. Electrochem. Soc.
155
,
H873
(
2008
).
20.
C.
Chen
and
J.
Kanicki
,
J. Appl. Phys.
108
,
114508
(
2010
).
21.
W.
Wang
,
L.
Li
,
C.
Lu
,
H.
Lv
,
G.
Xu
,
Z.
Ji
, and
M.
Liu
,
Appl. Phys. Lett.
107
,
063504
(
2015
).
22.
S.
Sadewasser
and
T.
Glatzel
,
Kelvin Probe Force Microscopy
(
Springer
,
2012
).
23.
B.
Popescu
,
M.
Hundhausen
, and
L.
Ley
,
J. Non-Cryst. Solids
283
(
1–3
),
155
(
2001
).
24.
V.
Vinciguerra
,
M.
La Rosa
,
D.
Nicolosi
,
G.
Sicurella
, and
L.
Occhipinti
,
Org. Electron.
10
,
1074
(
2009
).
25.
M.
Marinkovic
,
D.
Belaineh
,
V.
Wagner
, and
D.
Knipp
,
Adv. Mater.
24
,
4005
(
2012
).
You do not currently have access to this content.