Influence of indium concentration and substrate temperature on the physical characteristicsof chemically sprayed ZnO:In thin films deposited from zinc pentanedionate and indiumsulfate

Abstract

Chemically sprayed indium-doped zinc oxide thin films (ZnO:In) were deposited on glasssubstrates starting from zinc pentanedionate and indium sulfate. The influence of both thedopant concentration in the starting solution and the substrate temperature on thetransport, morphology, composition, linear and nonlinear optical (NLO) properties ofthe ZnO:In thin films were studied. The structure of all the ZnO:In thin filmswas polycrystalline, and variation in the preferential growth with the indiumcontent in the solution was observed: from an initial (002) growth in films withlow In content, switching to a predominance of (101) planes for intermediatedopant regime, and finally turning to a (100) growth for heavily doped films. Thecrystallite size was found to decrease with doping concentration and range from 36 to23 nm. The film composition and the dopant concentration were determined byRutherford backscattering spectrometry; these results showed that the films are almoststoichiometric ZnO. The optimum deposition conditions leading to conductiveand transparent ZnO:In thin films were also found. In this way a resistivity of4 × 10−3 Ω cm and an average transmittance in the visible spectra of 85%, with a (101) preferentialgrowth, were obtained in optimized ZnO:In thin films.