The conductive atomic force microscope (CAFM) has become an essential tool for the nanoscale electronic characterization of many materials and devices. When studying photoactive samples, the laser used by the CAFM to detect the deflection of the cantilever can generate photocurrents that perturb the current signals collected, leading to unreliable characterization. In metal-coated semiconductor samples, this problem is further aggravated, and large currents above the nanometer range can be observed even without the application of any bias. Here we present the first characterization of the photocurrents introduced by the laser of the CAFM, and we quantify the amount of light arriving to the surface of the sample. The mechanisms for current collection when placing the CAFM tip on metal-coated photoactive samples are also analyzed in-depth. Finally, we successfully avoided the laser-induced perturbations using a two pass technique: the first scan collects the topography (laser ON) and the second collects the current (laser OFF). We also demonstrate that CAFMs without a laser (using a tuning fork for detecting the deflection of the tip) do not have this problem.

1.
D.
Kajewski
,
R.
Wrzalik
,
M.
Wojtyniak
,
M.
Pilch
,
J.
Szade
,
K.
Szot
,
C.
Lenser
,
R.
Dittmann
, and
R.
Waser
,
Phase Transitions
84
(
5-6
),
483
488
(
2011
).
2.
M.
Lanza
,
M.
Porti
,
M.
Nafría
,
X.
Aymerich
,
G.
Benstetter
,
E.
Lodermeier
,
H.
Ranzinger
,
G.
Jaschke
,
S.
Teichert
,
L.
Wilde
, and
P.
Michalowski
,
IEEE Trans. Nanotechnol.
10
(
2
),
344
351
(
2011
).
3.
R.
Garcia
,
R. V.
Martinez
, and
J.
Martinez
,
Chem. Soc. Rev.
35
(
1
),
29
38
(
2006
).
4.
M.
Lanza
,
Materials
7
(
3
),
2155
2182
(
2014
).
5.
W.
Frammelsberger
,
G.
Benstetter
,
J.
Kiely
, and
R.
Stamp
,
Appl. Surf. Sci.
252
(
6
),
2375
2388
(
2006
).
6.
G. H.
Buh
and
J. J.
Kopanski
,
Appl. Phys. Lett.
83
(
12
),
2486
2488
(
2003
).
7.
M. N.
Chang
,
C. Y.
Chen
,
W. J.
Huang
, and
T. C.
Cheng
,
Appl. Phys. Lett.
87
(
2
),
023102
(
2005
).
8.
M. N.
Chang
and
C. Y.
Chen
,
Appl. Phys. Lett.
89
(
13
),
133109
(
2006
).
9.
M. K.
Hota
,
M. N.
Hedhili
,
Q.
Wang
,
V. A.
Melnikov
,
O. F.
Mohammed
, and
H. N.
Alshareef
,
Adv. Electron. Mater.
1
(
3
),
1400035
(
2015
).
10.
D.
Kim
,
J.
Yoon
,
J.
Park
,
H.
Hwang
,
Y. M.
Kim
,
S. H.
Kwon
, and
K. H.
Kim
,
Appl. Phys. Lett.
98
(
15
),
152107
(
2011
).
11.
A. G.
Scheuermann
,
J. D.
Prange
,
M.
Gunji
,
C. E. D.
Chidsey
, and
P. C.
McIntyre
,
Energy Environ. Sci.
6
(
8
),
2487
2496
(
2013
).
12.
H. R.
Moutinho
,
R. G.
Dhere
,
C. S.
Jiang
,
M. M.
Al-Jassim
, and
L. L.
Kazmerski
,
Thin Solid Films
514
(
1-2
),
150
155
(
2006
).
13.
J.
Alvarez
,
J. P.
Kleider
,
F.
Houze
,
M. Y.
Liao
, and
Y.
Koide
,
Diamond Relat. Mater.
16
(
4-7
),
1074
1077
(
2007
).
14.
F.
Giannazzo
,
S.
Sonde
,
V.
Raineri
, and
E.
Rimini
,
Appl. Phys. Lett.
95
(
26
),
263109
(
2009
).
15.
X.
Sun
and
Z.
Ding
,
J. Phys. D: Appl. Phys.
38
(
3
),
456
459
(
2005
).
16.
S.
Kremmer
,
S.
Peissl
,
C.
Teichert
,
F.
Kuchar
, and
H.
Hofer
,
Mater. Sci. Eng. B
102
(
1-3
),
88
93
(
2003
).
17.
I.
Horcas
,
R.
Fernández
,
J. M.
Gómez-Rodríguez
,
J.
Colchero
,
J.
Gómez-Herrero
, and
A. M.
Baro
,
Rev. Sci. Instrum.
78
(
1
),
013705
(
2007
).
18.
See supplementary material at http://dx.doi.org/10.1063/1.4960597 for: (i) topographic and current maps for the Ir/TiO2/SIO2/n-Si sample in air and vacuum, (ii) CAFM current maps and the corresponding cross sections in the Ni/SiO2/n-Si, and (iii) SEM images, CAFM current maps and cross sections in the Ni/SiO2/n-Si.
19.
M. J.
Kenney
,
M.
Gong
,
Y.
Li
,
J. Z.
Wu
,
J.
Feng
,
M.
Lanza
, and
H.
Dai
,
Science
342
(
6160
),
836
840
(
2013
).
20.
T.
Wang
and
J.
Gong
,
Angew. Chem., Int. Ed.
54
(
37
),
10718
10732
(
2005
).
21.
D.
Nocera
,
Acc. Chem. Res.
45
(
5
),
767
776
(
2012
).
22.
D. V.
Esposito
,
I.
Levin
,
T. P.
Moffat
, and
A. A.
Talin
,
Nat. Mater.
12
(
6
),
562
568
(
2013
).
23.
M.
Lanza
,
A.
Bayerl
,
T.
Gao
,
M.
Porti
,
M.
Nafria
,
G.
Jing
,
Y.
Zhang
,
Z.
Liu
, and
H.
Duan
,
Adv. Mater.
25
,
1440
1444
(
2013
).
24.
M.
Lanza
,
M.
Porti
,
M.
Nafría
,
X.
Aymerich
,
E.
Wittaker
, and
B.
Hamilton
,
Rev. Sci. Instrum.
81
,
106110
(
2010
).

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