Title

Electrical conductivity mechanisms in zinc oxide thin films deposited by pulsed laser deposition using different growth environments

Authors

Authors

S. P. Heluani; G. Braunstein; M. Villafuerte; G. Simonelli;S. Duhalde

Comments

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Abbreviated Journal Title

Thin Solid Films

Keywords

zinc oxide; electrical properties; conduction mechanisms; P-TYPE ZNO; DEVICES; Materials Science, Multidisciplinary; Materials Science, Coatings &; Films; Physics, Applied; Physics, Condensed Matter

Abstract

The mechanisms of electrical conduction in zinc oxide thin films, grown by pulsed laser deposition, have been investigated as a function of preparation conditions. The films were deposited on glass and silicon nitride coated silicon, using oxygen rich, oxygen deficient, or nitrogen atmospheres. The substrates were held at 473 K during deposition, and subsequently cooled down to room temperature in oxygen rich atmosphere of 4 Pa, or oxygen deficient atmosphere of 2 x 10(-3) Pa. Films deposited and cooled in an oxygen deficient atmosphere exhibited very high donor concentration, originated in intrinsic defects, and an impurity band related mechanism of conduction. Films deposited under relatively high oxygen pressure were highly resistive and showed, upon ultraviolet light irradiation, gain boundary controlled electrical transport. An enhancement of the conductivity was observed when using a nitrogen atmosphere during the deposition, and oxygen atmosphere during cooling. In this case, the dependence of the conductivity with temperature followed Mons' Law of variable range hopping, characteristic of a material with localized states randomly located in space. Since the density of hopping centers appears to be much larger than the density of nitrogen incorporated in this sample, it is suggested that the nitrogen induces defects in the zinc oxide lattice that behave as localized hopping centers, as well as carrier suppliers, giving rise to the observed conductivity. (c) 2006 Elsevier B.V. All rights reserved.

Journal Title

Thin Solid Films

Volume

515

Issue/Number

4

Publication Date

1-1-2006

Document Type

Article

Language

English

First Page

2379

Last Page

2386

WOS Identifier

WOS:000242931900183

ISSN

0040-6090

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