This study examined the optical and electronic properties of post-annealed Al-doped ZnO (ZnO:Al) thin films. The lowest resistivity was observed after annealing a sputter-deposited ZnO:Al film at . X-ray photoelectron spectroscopy revealed a shift in the Fermi level when the carrier concentration was increased to by Al doping and annealing. The optical band gap increased from 3.2 eV for insulating ZnO to 3.4 eV for conducting ZnO:Al, and was associated with conduction-band filling up to in a renormalized band gap. Schematic band diagrams are shown for the ZnO and ZnO:Al films.
REFERENCES
1.
T.
Minami
, Semicond. Sci. Technol.
20
, S35
(2005
).2.
L.
Schmidt-Mende
and J. L.
MacManus-Driscoll
, Mater. Today
10
, 40
(2007
).3.
C.
Jeong
, H. -S.
Kim
, D. -R.
Chang
, and K.
Kamisako
, Jpn. J. Appl. Phys.
47
, 5656
(2008
).4.
C.
Agashe
, O.
Kluth
, J.
Hüpkes
, U.
Zastrow
, B.
Rech
, and M.
Wuttig
, J. Appl. Phys.
95
, 1911
(2004
).5.
B. -Y.
Oh
, M. -C.
Jeong
, W.
Lee
, and J. -M.
Myoung
, J. Cryst. Growth
274
, 453
(2005
);M. -J.
Lee
, T. -I.
Lee
, J.
Lim
, J.
Bang
, W.
Lee
, T.
Lee
, and J. -M.
Myoung
, Electron. Mater. Lett.
5
, 127
(2009
).6.
K.
Kim
, K.
Park
, and D.
Ma
, J. Appl. Phys.
81
, 7764
(1997
).7.
J. G.
Lu
, Z. Z.
Ye
, Y. J.
Zeng
, L. P.
Zhu
, L.
Wang
, J.
Yuan
, B. H.
Zhao
, and Q. L.
Liang
, J. Appl. Phys.
100
, 073714
(2006
).8.
K. -K.
Kim
, H.
Tampo
, J. -O.
Song
, T. -Y.
Seong
, S. -J.
Park
, J. -M.
Lee
, S. -W.
Kim
, S.
Fujita
, and S.
Niki
, Jpn. J. Appl. Phys., Part 1
44
, 4776
(2005
).9.
G. J.
Fang
, D. J.
Li
, and B. -L.
Yao
, Phys. Status Solidi A
193
, 139
(2002
).10.
C.
Lennon
, R. B.
Tapia
, R.
Kodama
, Y.
Chang
, S.
Sivananthan
, and M.
Deshpande
, J. Electron. Mater.
38
, 1568
(2009
).11.
K. -K.
Kim
, S.
Niki
, J. -Y.
Oh
, J. -O.
Song
, T. -Y.
Seong
, S. -J.
Park
, S.
Fujita
, and S. -W.
Kim
, J. Appl. Phys.
97
, 066103
(2005
).12.
B. -Y.
Oh
, M. -C.
Jeong
, D. -S.
Kim
, W.
Lee
, and J. -M.
Myoung
, J. Cryst. Growth
281
, 475
(2005
).13.
O.
Bamiduro
, H.
Mustafa
, R.
Mundle
, R. B.
Konda
, and A. K.
Pradhan
, Appl. Phys. Lett.
90
, 252108
(2007
).14.
S. -S.
Lin
, J. -L.
Huang
, and P.
Šajgalik
, Surf. Coat. Technol.
185
, 254
(2004
).15.
J. I.
Pankove
, Optical Processes in Semiconductors
(Dover
, New York
, 1975
), pp. 93
–94
.16.
J.
Tauc
, Mater. Res. Bull.
5
, 721
(1970
).17.
E.
Burstein
, Phys. Rev.
93
, 632
(1954
).18.
B. E.
Sernelius
, K. -F.
Berggren
, Z. -C.
Jin
, I.
Hamberg
, and C. G.
Granqvist
, Phys. Rev. B
37
, 10244
(1988
).19.
Y.
Gassenbauer
, R.
Schafranek
, A.
Klein
, S.
Zafeiratos
, M.
Hävecker
, A.
Knop-Gericke
, and R.
Schlögl
, Phys. Rev. B
73
, 245312
(2006
).20.
D. -R.
Jung
, D.
Son
, J.
Kim
, C.
Kim
, and B.
Park
, Appl. Phys. Lett.
93
, 163118
(2008
).21.
K.
Ellmer
, A.
Klein
, and B.
Rech
, Transparent Conductive Zinc Oxide: Basics and Applications in Thin Film Solar Cells
(Springer
, Berlin
, 2008
), pp. 140
–147
.22.
L.
Ley
, R. A.
Pollak
, F. R.
McFeely
, S. P.
Kowalczyk
, and D. A.
Shirley
, Phys. Rev. B
9
, 600
(1974
).23.
J. A.
Sans
, J. F.
Sánchez-Royo
, A.
Segura
, G.
Tobias
, and E.
Canadell
, Phys. Rev. B
79
, 195105
(2009
).24.
J. G.
Lu
, S.
Fujita
, T.
Kawaharamura
, H.
Nishinaka
, Y.
Kamada
, T.
Ohshima
, Z. Z.
Ye
, Y. J.
Zeng
, Y. Z.
Zhang
, L. P.
Zhu
, H. P.
He
, and B. H.
Zhao
, J. Appl. Phys.
101
, 083705
(2007
).25.
See supplementary material at http://dx.doi.org/10.1063/1.3419859 for the binding energies, XRD patterns, grain size, and lattice constant of the ZnO and ZnO:Al films.
© 2010 American Institute of Physics.
2010
American Institute of Physics
You do not currently have access to this content.
