Electronic structures and stability of substitutional Ti3+ clusters in Al2O3 were investigated by first-principles pseudopotential calculations using large supercells. It was found that a substitutional Ti3+ defect induces an extra defect level in the band gap, and the defect levels have strong bonding interactions in the cluster formation. In addition, binding energies of Ti3+ clusters increased with increasing numbers of Ti3+ ions, indicating that cluster formation is energetically favorable. The resulting impurity band within the band gap of Al2O3 will contribute to the significant electronic conduction of Ti-doped Al2O3 observed experimentally.

1.
R. H.
French
,
J. Am. Ceram. Soc.
73
,
477
(
1990
).
2.
M. L.
Boltz
and
R. H.
French
,
Appl. Phys. Lett.
55
,
1955
(
1989
).
3.
A.
Nakamura
,
K.
Matsunaga
,
J.
Tohma
,
T.
Yamamoto
, and
Y.
Ikuhara
,
Nat. Mater.
2
,
453
(
2003
).
4.
S. K.
Mohapatra
and
F. A.
Kröger
,
J. Am. Ceram. Soc.
60
,
381
(
1977
).
5.
K.
Matsunaga
,
A.
Nakamura
,
T.
Yamamoto
, and
Y.
Ikuhara
,
Phys. Rev. B
68
,
214102
(
2003
).
6.
W. D.
McKee
, Jr.
and
E.
Aleshin
,
J. Am. Ceram. Soc.
46
,
54
(
1963
).
7.
W. M.
Chen
,
I. A.
Buyanova
,
A. V.
Buyanov
, and
T.
Lundstrom
,
Phys. Rev. Lett.
77
,
2734
(
1996
).
8.
W. M.
Chen
,
P.
Dreszer
,
A.
Prasad
,
A.
Kurpiewski
,
W.
Walukiewicz
,
E. R.
Weber
,
E.
Sorman
,
B.
Monemar
,
B. W.
Liang
, and
C. W.
Tu
,
J. Appl. Phys.
76
,
1
(
1994
).
9.
T. M.
Schmidt
,
R. H.
Miwa
,
A.
Fazzio
, and
R.
Mota
,
Phys. Rev. B
60
,
16475
(
1999
).
10.
G. Kresse, thesis, Technische Universität Wien, 1993.
11.
G.
Kresse
and
J.
Furthmüller
,
Comput. Mater. Sci.
6
,
15
(
1996
).
12.
D.
Vanderbilt
,
Phys. Rev. B
41
,
7892
(
1990
).
13.
G.
Kresse
and
J.
Hafner
,
J. Phys.: Condens. Matter
6
,
8245
(
1994
).
14.
S. B.
Zhang
and
J. E.
Northrup
,
Phys. Rev. Lett.
67
,
2339
(
1991
).
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