TCM 2016 ABSTRACT BOOK - page 135

Low temperature Pulsed Laser Deposited Highly Transparent and Conductive
vanadium-doped Zinc Oxide (VZO) Thin Films
A. Smaali-Lafane1 *, S. Abdelli-Messaci1 , S. Lafane1, M. Kechouane2, J. Lenzner3,
S. Richter4, O. Nemraoui5, K. Ellmer 6
1) Division Milieux Ionisés et Laser, Centre de Développement des Technologies Avancées,
Cité 20 août 1956, B. P. 17, Baba Hassen, Algiers, Algeria
2) Faculté de Physique, Université des Sciences et Technologies Houari Boumediene, BP 32
EL ALIA 16111 BabEzzouar, Algiers, Algeria
3)Universität Leipzig, Fakultätfür Physikund Geowissenschaften Abteilung Halbleiterphysik
Zimmer 211 Linnestrasse 5, D-04103 Leipzig, Germany
4)Universität Leipzig, Institutfür Experimentelle Physik II, Linnéstra ße 5, 04103 Leipzig,
Germany
5)Mechatronics, Cape Peninsula University of technology P.O. Box 1906, Bellville 7535,
South Africa
6)Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Solar Fuels,
Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
*A.Smaali-Lafane, Cité 20 août 1956, B. P. 17, Baba Hassen, Algeria, asmaali@cdta.dz,
In the last decade, vanadium had been introduced as a new dopant for transparent and
conductive ZnO thin films. Up to now, only few reports on this new dopant have been
published showing that depending on the preparation conditions wide resistivities variation of
VZO films can be obtained for different deposition methods. The pulsed laser deposition
(PLD) technique, so far, has not been used to prepare VZO films as a TCO material although
its attractive advantages consisting of high film quality and easy control of the composition.
In this work, we deposited transparent and conductive VZO films using the PLD technique
by systematically varying the dopant concentration. Vanadium doped ZnO films were
deposited on corning glass substrates by ablating ceramic ZnO-V2O5 targets using a KrF
excimer laser (248 nm, 25 ns) under oxygen ambience. Besides the temperature growth (from
200°C to 600°C) influence on the properties of a series of pure ZnO films, the study
evaluated the effect of the doping amount on the crystal structure, surface morphology,
electrical and optical properties of two series deposited at 500°C and 200°C with doping
amounts varying from 0.4 to 1.8 at.%. Films thickness is around 500 nm.
While varying temperature from 200°C to 600°C, there is no much influence impact on the
electrical and optical properties of the pure ZnO films. The films have an average
transmittance of 80% within the visible-NIR region. The free carrier concentration is around
2 1019 cm-3 and the Hall mobility lying between 41 and 49 cm2/Vs yielding to a resistivity
around 7 10-3 Ωcm.
On the other hand, by reducing the substrate temperature from 500°C to 200°C for VZO
films, low growth temperature with comparable electrical and optical properties to ITO are
obtained. The VZO films are transparent (~ 75%) in the 400-1200 nm wavelength range. The
resistivity decreases with increasing vanadium content up to 0.9 at.% doping with a minimum
of 1.1 10-3 Ωcm at 500°C while it reaches 5 10 -4 Ωcm at 200°C substrate temperature. The
carrier concentration and Hall mobility are of (2.3 1020 cm-3, 30 cm2/Vs) and (7 1020 cm-3,
17 cm2/Vs) at 500 and 200°C, respectively. The structure analysis and layers morphology,
strongly influenced by the doping amount, will be also discussed in detail.
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