Properties of tantalum oxide thin films grown by atomic layer deposition

doi:10.1016/0040-6090(94)06388-5

Thin Solid Films

Volume 260, Issue 2, 15 May 1995, Pages 135-142

https://doi.org/10.1016/0040-6090(94)06388-5 Get rights and content

Abstract

Thin tantalum oxide films were deposited using atomic layer deposition from TaCl₅ and H₂O at temperatures in the range 80–500 °C. The films deposited at temperatures below 300 °C were predominantly amorphous, whereas those grown at higher temperatures were polycrystalline containing the phases TaO₂ and Ta₂O₅. The oxygen to tantalum mass concentration ratio corresponded to that of TaO₂ at all growth temperatures. The optical band gap was close to 4.2 eV for amorphous films and ranged from 3.9 to 4.5 eV for polycrystalline films. The refractive index measured at λ = 550 nm increased from 1.97 to 2.20 with an increase in growth temperature from 80 to 300 °C. The films deposited at 80 °C showed low absorption with absorption coefficients of less than 100 cm⁻¹ in the visible region.

References (34)

F. Rubio et al.
Thin Solid Films
(1982)
S.B. Desu
Mater. Chem. Phys.
(1992)
K. Gürtler et al.
Thin Solid Films
(1989)
S.-O. Kim et al.
Thin Solid Films
(1991)
Y. Nishimura et al.
Thin Solid Films
(1993)
H. Kattelus et al.
Thin Solid Films
(1993)
J. Aarik et al.
Appl. Surf. Sci.
(1994)
J. Aarik et al.
J. Cryst. Growth
(1994)
J. Aarik et al.
Appl. Surf. Sci.
(1994)
E.E. Khawaja et al.
Thin Solid Films
(1975)

H. Demiryont et al.

Appl. Opt.

(1985)

A.J. Waldorf et al.

Appl. Opt.

(1993)

H.O. Sankur et al.

Appl. Opt.

(1989)

G.Q. Lo et al.

Appl. Phys. Lett.

(1993)

P.A. Murawala et al.

Jpn. J. Appl. Phys.

(1993)

K. Shimizu et al.

J. Appl. Phys.

(1993)

M. Matsui et al.

Jpn. J. Appl. Phys.

(1990)

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Properties of tantalum oxide thin films grown by atomic layer deposition

Abstract

Thin Solid Films

Mater. Chem. Phys.

Thin Solid Films

Thin Solid Films

Thin Solid Films

Thin Solid Films

Appl. Surf. Sci.

J. Cryst. Growth

Appl. Surf. Sci.

Thin Solid Films

Appl. Opt.

Appl. Opt.

Appl. Opt.

Appl. Phys. Lett.

Jpn. J. Appl. Phys.

J. Appl. Phys.

Jpn. J. Appl. Phys.