Growth of Al₂O₃ thin film by oxidation of resistively evaporated Al on top of SnO₂, and electrical properties of the heterojunction SnO₂/Al₂O₃

Author： Maciel Jorge Floriano Emerson Scalvi Luis Ravaro Leandro

Publisher： Springer Publishing Company

ISSN： 0022-2461

Source： Journal of Materials Science, Vol.46, Iss.20, 2011-10, pp. : 6627-6632

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Abstract

Aiming for the investigation of insulating properties of aluminum oxide (Al₂O₃) layers, as well as the combination of this oxide with tin dioxide (SnO₂) for application in transparent field effect transistors, Al thin films are deposited by resistive evaporation on top of SnO₂ thin films deposited by sol–gel dip-coating process. The oxidation of Al films to Al₂O₃ are carried out by thermal annealing at 500 °C in room conditions or oxygen atmosphere. X-ray diffraction data indicate that tetragonal Al₂O₃ is indeed obtained. A simple device and electric circuit is proposed to measure the insulating properties of aluminum oxide and the transport properties of SnO₂ as well. Results indicate a fair insulation when four layers or Al₂O₃ are grown on the tin dioxide film, concomitant with thermal annealing between each layer. The current magnitude through the insulating layer is only 0.2% of the current through the semiconductor film, even though the conductivity of the SnO₂ alone is not very high (the average resistivity is 2 Ω cm), because no doping is used. The presented results are a good indication that this combination may be useful for transparent devices.