Structural, optical and electrical properties of low temperature grown undoped and (Al, Ga) co-doped ZnO thin films by spray pyrolysis

Journal article

Authors / Editors

Mbaiwa, Foster

Research Areas

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Publication Details

Author list: Makuku O, Mbaiwa F, Sathiaraj TS

Publisher: Elsevier

Place: OXFORD

Publication year: 2016

Journal: Ceramics International (0272-8842)

Journal acronym: CERAM INT

Volume number: 42

Issue number: 13

Start page: 14581

End page: 14586

Number of pages: 6

ISSN: 0272-8842

eISSN: 1873-3956

Languages: English-Great Britain (EN-GB)

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Abstract

Aluminum and gallium co-doped ZnO (AGZO) thin films were grown by simple, flexible and cost-effective spray pyrolysis method on glass substrates at a temperature of 230 degrees C. Effects of equal co-doping with aluminum (Al) and gallium (Ga) on structural, optical and electrical properties were investigated by X-ray diffraction (XRD), UV-vis-NIR spectrophotometry and Current-Voltage (I-V) measurements, respectively. XRD patterns showed a successful growth with high quality polycrystalline films on glass substrates. The predominant orientation of the films is (002) at dopant concentrations <= 2 at% and (101) at higher dopant concentrations. Incorporation of Al and Ga to the ZnO crystal structure decreased the crystallite size and increased residual stress of the thin films. All films were highly transparent in the visible region with average transmittance of 80%. Increasing doping concentrations increased the optical band gap, from 3.12 to 3.30 eV. A blue shift of the optical band gap was observed from 400 nm to 380 nm with increase in equal co-doping. Co-doping improved the electrical conductivity of ZnO thin films. It has been found from the electrical measurements that films with dopant concentration of 2 at% have lowest resistivity of 1.621 x 10(-4) SL cm. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Keywords

AGZO films, Electrical properties, Optical properties, ZnO

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