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Effects of Thermal Processing on Transparent Conducting Oxides (TCO) Used in Optoelectronic Devices



Author(s)

Zakia Fekkai

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DOI:10.17265/2161-6221/2013.03.001

Department of Physics, Al Imam Mohammad Ibn Saud Islamic University, Riyadh 11623, Saudi Arabia

Due to its high electrical conductivity and high transparency in the visible light wavelength range, transparent conductive oxide thin films are able to be used as semiconductor materials on electronic devices. Among these films/materials, zinc oxides (ZnO), indium oxides (In2O3) and tin oxide thin films (SnO2) which are particularly attractive due to their optical, electrical and mechanical properties. In this investigation, the metal oxide films were prepared by pulsed laser deposition technique (PLD) using the same deposition parameters. The electrical, structural, and optical properties of these films were examined. The resistivity of the films were calculated based on the sheet resistance Rs measured by the standard four-point probe technique at room temperature. Concerning the structural properties, all films presented uniform, dense and smooth surface. The films were annealed for 1 hour at different temperatures (200-600 °C) in an argon atmosphere. Annealing greatly decreased the resistivity of the films. Atomic Force microscopy (AFM) measurements revealed an increase in surface roughness of the annealed films with temperature. Improvement to the crystallinity was observed from the double layers (SnO2)/(ZnO) annealed at 300-400 °C and above with a slight decrease in the optical transmittance. The transmittance of these films was measured in the spectrum range 200-2,000 nm using a spectrophotomer. High transmittance above (85%) in the visible region was exhibited by the films annealed at 400 °C and above. A lower resistivity and better spectra selectivity is a measurement of the quality and potential use of indium/tin oxides onto intrinsic zinc oxide deposited on cleaned glass substrates, for the application as transparent electrodes of electronic devices such as solar cells and organic light- emitting diodes.

Transparent conducting oxides, optical properties, annealing, pulsed laser deposition, optoelectronic devices.