The dynamics of photogenerated electrons and holes in undoped anatase TiO2 were studied by femtosecond absorption spectroscopy from the visible to mid-infrared region (0.1–2.0 eV). The transient absorption spectra exhibited clear metallic responses, which were well reproduced by a simple Drude model. No mid-gap absorptions originating from photocarrier localization were observed. The reduced optical mass of the photocarriers obtained from the Drude-model analysis is comparable to theoretically expected one. These results demonstrate that both photogenerated holes and electrons act as mobile carriers in anatase TiO2. We also discuss scattering and recombination dynamics of photogenerated electrons and holes on the basis of the time dependence of absorption changes.
REFERENCES
1.
A.
Fujishima
and K.
Honda
, Nature
238
, 37
(1972
).2.
B.
O'Regan
and M.
Grätzel
, Nature
353
, 737
(1991
).3.
L.
Forro
, O.
Chauvet
, D.
Emin
, L.
Zuppiroli
, H.
Berger
, and F.
Lévy
, J. Appl. Phys.
75
, 633
(1994
).4.
Y.
Matsumoto
, M.
Murakami
, Z. W.
Jin
, A.
Nakayama
, T.
Yamaguchi
, T.
Ohmori
, E.
Suzuki
, S.
Nomura
, M.
Kawasaki
, and H.
Koinuma
, Proc. SPIE
3941
, 19
(2000
).5.
Y.
Matsumoto
, M.
Murakami
, T.
Shono
, T.
Hasegawa
, T.
Fukumura
, M.
Kawasaki
, P.
Ahmet
, T.
Chikyow
, S.
Koshihara
, and H.
Koinuma
, Science
291
, 854
(2001
).6.
Y.
Furubayashi
, T.
Hitosugi
, Y.
Yamamoto
, K.
Inaba
, G.
Kinoda
, Y.
Hirose
, T.
Shimada
, and T.
Hasegawa
, Appl. Phys. Lett.
86
, 252101
(2005
).7.
T.
Hitosugi
, Y.
Furubayashi
, A.
Ueda
, K.
Itabashi
, K.
Inaba
, Y.
Hirose
, G.
Kinoda
, Y.
Yamamoto
, T.
Shimada
, and T.
Hasegawa
, Jpn. J. Appl. Phys., Part 2
44
, L1063
(2005
).8.
T.
Hitosugi
, H.
Kamisaka
, K.
Yamashita
, H.
Nogawa
, Y.
Furubayashi
, S.
Nakao
, N.
Yamada
, A.
Chikamatsu
, H.
Kumigashira
, M.
Oshima
, Y.
Hirose
, T.
Shimada
, and T.
Hasegawa
, Appl. Phys. Express
1
, 111203
(2008
).9.
Y.
Furubayashi
, N.
Yamada
, Y.
Hirose
, Y.
Yamamoto
, M.
Otani
, T.
Hitosugi
, T.
Shimada
, and T.
Hasegawa
, J. Appl. Phys.
101
, 093705
(2007
).10.
Y.
Hirose
, N.
Yamada
, S.
Nakao
, T.
Hitosugi
, T.
Shimada
, and T.
Hasegawa
, Phys. Rev. B
79
, 165108
(2009
).11.
Y.
Tamaki
, A.
Furube
, M.
Murai
, K.
Hara
, R.
Katoh
, and M.
Tachiya
, J. Am. Chem. Soc.
128
, 416
(2006
).12.
A.
Fujishima
, X. T.
Zhang
, and D. A.
Tryk
, Surf. Sci. Rep.
63
, 515
(2008
).13.
Y.
Kozuka
, T.
Susaki
, and H. Y.
Hwang
, Phys. Rev. Lett.
101
, 096601
(2008
).14.
H.
Okamoto
, T.
Miyagoe
, K.
Kobayashi
, H.
Uemura
, H.
Nishioka
, H.
Matsuzaki
, A.
Sawa
, and Y.
Tokura
, Phys. Rev. B
82
, 060513
–R
(2010
).15.
H.
Okamoto
, T.
Miyagoe
, K.
Kobayashi
, H.
Uemura
, H.
Nishioka
, H.
Matsuzaki
, A.
Sawa
, and Y.
Tokura
, Phys. Rev. B
83
, 125102
(2011
).16.
T.
Asahi
, A.
Furube
, and H.
Masuhara
, Chem. Phys. Lett.
275
, 234
(1997
).17.
N. A.
Anderson
and T.
Lian
, Coord. Chem. Rev.
248
, 1231
(2004
).18.
P.
Tiwana
, P.
Parkinson
, M. B.
Johnston
, H. J.
Snaith
, and L. M.
Herz
, J. Phys. Chem. C
114
, 1365
(2010
).19.
Y.
Tamaki
, K.
Hara
, R.
Katoh
, M.
Tachiya
, and A.
Furube
, J. Phys. Chem. C
113
, 11741
(2009
).20.
J. K.
Burdett
, T.
Hughbanks
, G. J.
Miller
, J. W.
Richardson
, and J. V.
Smith
, J. Am. Chem. Soc.
109
, 3639
(1987
).21.
J. Y.
Vinet
, M.
Combescot
, and C.
Tanguy
, Solid State Commun.
51
, 171
(1984
).22.
R. J.
Gonzalez
, R.
Zallen
, and H.
Berger
, Phys. Rev. B
55
, 7014
(1997
).23.
The error in μ comes from the error in the evaluation of NC(0). The carrier density NC(0) was calculated from NC(0) = 2xph = Ip(1 − Rp)/lp, and thus the error in NC(0) can originate from the errors in the three parameters Ip, Rp, and lp. The errors in Ip and lp were estimated to be ±2%. The error in lp comes from the measurement of the film thickness. The error in Rp was smaller than ±0.5%. Therefore, the error of NC(0) was estimated to be within ±4%. This gave μ = (0.37 ± 0.015)m0.
24.
L.
Thulin
and J.
Guerra
, Phys. Rev. B
77
, 195112
(2008
).25.
H.
Kamisaka
, T.
Hitosugi
, T.
Suenaga
, T.
Hasegawa
, and K.
Yamashita
, J. Chem. Phys.
131
, 034702
(2009
).26.
H. A.
Huy
, B.
Aradi
, T.
Frauenheim
, and P.
Deák
, Phys. Rev. B
83
, 155201
(2011
).27.
H.
Okamoto
, Y.
Ishige
, S.
Tanaka
, H.
Kishida
, S.
Iwai
, and Y.
Tokura
, Phys. Rev. B
70
, 165202
(2004
).28.
H. M.
Ma
, Y. X.
Liu
, Y.
Fei
, and F. M.
Li
, J. Appl. Phys.
65
, 5031
(1989
).29.
Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light
, edited by M.
Born
and E.
Wolf
(Cambridge University Press
, New York
, 1999
).30.
D. B. M.
Klaassen
, Solid State Electron.
35
, 953
(1992
).31.
E.
Hendry
, M.
Koeberg
, J.
Pijpers
, and M.
Bonn
, Phys. Rev. B
75
, 233202
(2007
).32.
J.
Bardeen
and W.
Shockley
, Phys. Rev.
80
, 72
(1950
).33.
G. D.
Sanders
, C.-K.
Sun
, B.
Golubovic
, J. G.
Fujimoto
, and C. J.
Stanton
, Phys. Rev. B
54
, 8005
(1996
).34.
B. Q.
Hu
, X. M.
Wang
, T.
Zhou
, Z. Y.
Zhao
, X.
Wu
, and X. L.
Chen
, Chin. Phys. Lett.
18
, 278
(2001
).© 2014 AIP Publishing LLC.
2014
AIP Publishing LLC
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