Ae. Desouza et al., ELECTRICAL AND OPTICAL CHARACTERISTICS OF SNO2 THIN-FILMS PREPARED BYDIP COATING FROM AQUEOUS COLLOIDAL SUSPENSIONS, Journal of materials science. Materials in electronics, 8(4), 1997, pp. 265-270
Starting from aqueous colloidal suspensions, undoped and Nb5+ doped Sn
O2 thin films have been prepared by using the dip-coating sol-gel proc
ess. X-ray diffraction results show that films are polycrystalline wit
h crystallites of average size 1-4 nm. Decreasing the thickness of the
films and increasing the Nb5+ concentration limits the crystallite si
ze growth during firing. Complex impedance measurements reveal capacit
ive and resistive effects between adjacent crystallites or grains, cha
racteristic of electrical potential barriers. The transfer of charge t
hroughout these barriers determines the macroscopic electrical resista
nce of the layer. The analysis of the optical absorption spectra shows
that the samples present more than 80% of their transmittance in the
visible region and the value of the band gap energy increases with dec
reasing crystallite size.