We have fabricated six SiO2 thin films by the spin coating of tetraethyl orthosilicate (TEOS) sol-gel solutions of different concentrations. It was found that the thickness of SiO2 film decreased as the concentration of TEOS decreased. Among six samples, 9 nm thick SiO2 film exhibited the highest secondary electron emission (SEE) yield. Moreover, SEE yields for sol-gel based SiO2 films were found to be higher than those for thermal SiO2 films. In order to confirm the applicability of this method, electron-amplifying microchannel plates (MCPs) with a sol-gel based SiO2 layer as an electron emissive layer were fabricated and their amplifying characteristics were investigated. Reasonably good current gains were obtained for those MCPs suggesting that this SiO2 layer formed by the sol-gel method was a good candidate for a SEE layer.