Preferred growth of siliceous MEL zeolite film on silicon wafer

Continuous and dense siliceous MEL type zeolite films were prepared by seeding methods on a silicon (100) substrate in the clear solution of TBAOH-TEOS-H2O. The effects of the precursor layer adsorbed on the substrate surface, the content of water in the reactant solution, the reaction period and the substrate position on the morphology and the orientation of MEL zeolite crystallites in the films were investigated. The zeolite films are composed of a monolayer of well-intergrowth zeolite crystallites grown preferentially along the (101) direction. The films less than 2 mu m in thickness are oriented, regardless of the wafer being covered with a precursor layer or not. The reaction period has an important effect on zeolite film orientation whether in the concentrate or in the dilute synthesis solution. The shorter reaction period is preferred. The oriented zeolite films grow either on the vertically placed substrates or on the horizontally placed substrates. (c) 2005 Elsevier Inc. All rights reserved.