Transparent semiconducting ZnO : Al thin films prepared by spray pyrolysis

Aluminum doped zinc oxide (ZnO:Al) films which can be used as transparent e lectrodes or heating layers have been deposited by the low cost spray pyrol ysis technique. Undoped and Al-doped ZnO films deposited using various prep aration conditions and on different substrates (soda lime glass, quartz gla ss and crystalline quartz, respectively) have been studied. The effect of s ubstrate type, temperature, deposition time and doping concentration on ZnO :Al thin layers have been investigated by analysing the optical and structu ral properties of the films. A substrate temperature of 770 K allows the pr eparation of nanosized ZnO:Al crystals with preferred [002] orientation. Fi lms with optical transmission T > 85% and a adjustable resistivity rho betw een 2 and 100 Omega cm have been obtained. The resistivity value of the fil ms can be adjusted by tuning suitable processing parameters. The feasibilit y of the spray pyrolysis technique for the preparation of thin semiconducti ng ZnO:Al films on conventional soda lime glass substrates is demonstrated. (C) 1999 Elsevier Science Ltd. All rights reserved.