Preparation Of Barium Titanate Nanodot Arrays On Si Substrate Through Sol-gel-template Way

BaTiO₃ is one of the most typical ferroelectric materials. Devices with ultrahigh density integration is becoming a dominant research direction, hence, BaTiO₃ nanodot arrays have attracted great interests.General ways of preparing nanodot arrays are photolithography, molecular beam epitaxy, sputtering, self-assembly, chemical vapor deposition and so on. In this paper, the sol-gel-template method, combined sol-gel way with nanochannel alumina templates, was proposed to prepare BaTiO₃ nanodot arrays. Compared with the other ways, this method owns two important and unique characters. One is the sol-gel-template way is very fit for multicomponent oxides, the other is no special request for substrate. During the experiment, silicon was used as a substrate, which could make sense in integrated circuits and chips.Formation of nanodot arrays has a close relation with gelation time. In this paper, changing trend of the gelation time with some factors were studied and discussed, such as temperature, pH value, concentration and so on. The results can provide a suitable sol for preparing nanodot arrays through sol-gel-template way. The results were showed as follows:1, the gelation time decreased with temperature increasing, and declined sharply between 60℃ and 70℃, then kept descending slowly.2, the gelation time decreased with pH increasing from 4.25 to 5.25, and showed a sudden descending form 4.50 to 4.75.3, the gelation time decreased with the concentration of BaTiO₃ increasing at a certain temperature. The lower temperature was, the more obviously it showed, while the gelation time showed a minor decline when the temperature was higher than 60X2BaTiO₃ nanodot arrays were prepared under appropriate sol conditions. By controlling the amount of sol, the substrate temperature and the sol concentration, the structure parameters of nanodot arrays changed orderly in a certain range. Theparameters include nanodot shape, distribution, size, size distribution. The changes were showed as follows:1, HOCH2CH2OCH3 was solvent, with increasing sol amount, the nanostructures changed from nanodot array to bulk thin film. The nanostructures were nanodot array, a mixture of nanodots and short rods, a mixture of rod and bulk thin film when the amount of sol were 2uL, 4uL, 8uL, respectively.2, HOCH2CH2OCH3 was solvent, with increasing temperature, dot density became larger( from 0.747x1014n/m2 to 2.64x1014n/m2), dot distribution was more uniform, dot size was smaller (average size is from 28nm to 21nm) and dot size distribution was more narrow, respectively.3, the influence trend of sol concentration was the same as substrate temperature. The differences were changing extent of dot density and dot size (dot density changed from 1.36xl014n/m2 to 2.44xl0Hn/m2 and dot size from 24nm tol8nm)4, when the solvent of sol was ethanol, there was a similar influence of preparation parameters as HOCH2CH2OCH3, but in the same condition dot density of the former was smaller than the one of the latter(from 1.04xl014 n/m2 to 2.44x1014 n/m2) and dot size bigger(from 37nm to 18nm).Finally, X-ray photoelectron spectroscopy confirmed that the dots were BaTiO3.