Atomic Layer Deposition of Electroactive V
2
O
5
Layers for Potential Energy Storage
and Electrochromic Applications
D. Vernardou
1
, M. Apostolopoulou
1
, N. Katsarakis
1,2,3
, E. Koudoumas
1,2
,
I.I. Kazadojev
4
, I.M. Povey
4
, S. O’Brien
4
and M.E. Pemble
4,5
*
1
Center of Materials Technology and Photonics, School of Applied Technology,
Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece
2
Electrical Engineering Department, School of Applied Technology, Technological
Educational Institute of Crete, 710 04 Heraklion, Crete, Greece
3
Institute of Electronic Structure and Laser, Foundation for Research & Technology-
Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete, Greece
4
Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork,
Ireland
5
Department of Chemistry, University College Cork, Lee Maltings, Prospect Row, Cork,
Ireland
*corresponding author,
Vanadium pentoxide (V
2
O
5
) has attracted a lot of attention as a cathode due to its reversible
redox reactions between valence states and an open framework layered structure offering
high capacity capabilities. However, the electrochemical response regarding charge capacity
and durability is limited by the low diffusion coefficient of Li ions in V
2
O
5
matrix. Although
improvements have already been demonstrated by various techniques such as chemical
vapour deposition, sputtering and hydrothermal process, films deposited by these methods
can suffer from low cycling stability and lack of uniformity over the entire substrate.
Consequently, atomic layer deposition (ALD), which enables uniform, highly-conformal film
growth at low temperature over the entire substrate may offer opportunities to improve
electrical properties.
In this study, ALD was used to grow V
2
O
5
films by using tertrakis(dimethylamino)vanadium
(IV) (V(NMe
2
)
4
) as the precursor at 300
o
C for 400 ALD cycles, followed by an annealing
step at 400
o
C in air for 1 h. Films were grown on ITO coated glass substrates with a surface
resistivity of 30-60 Ω/sq (Sigma-Aldrich). Thin films were deposited using a Cambridge-
Nanotech Fiji system. Thermal and Plasma growth processes were utilized for the growth of
V
2
O
5
films and will be described in detail.
In the case of ‘as-grown’ films, samples prepared using a plasma process were observed to be
polycrystalline, however ‘as-grown’ samples prepared by thermal ALD were largely
amorphous, with only very low intensity XRD features observed during characterization. The
effects of these different growth processes on V
2
O
5
thin film microstructure and resulting
electrochemical properties is discussed, in addition to possible applications as cathodes in
electrochromics and in lithium ion batteries.
PS1 12
-168-
