SnO2:Sb transparent conducting coatings made by different sol-gel processes

Abstract

Single and multilayer sol-gel coatings of transparent antimony-doped tin oxide (SnO2:Sb) have been prepared on borosilicate and fused silica substrates using either a 5 mole% SbCl3 doped 0.5 M solution of SnCl2(OAc)2 in ethanol or a water suspension of crystalline Sb-doped tin oxide nanoparticles. The nanoscale morphology and the electrical parameters of the layers have been determined after different firing procedures and heating rates varying from 0.2 to 4300 K/s obtained either in a furnace or by cw carbon- dioxide laser irradiation. For a given sintering temperature (approximately 540 degrees Celsius) a slow heating process in furnace leads to porous, homogeneous single and multilayers consisting of small crystallites. They present a high resistivity of about Ρ=4 X 10-2 Ωcm. With increasing heating rate the layers become denser with larger crystallites and the resistivity value decrease down to approximately 7 X 10-3 Ωcm for 4300 K/s (carbon-dioxide laser sintering). It is proposed that the densification of the coatings is determined by a competition between nucleation at low temperatures and the growth of the crystallites at high temperatures.