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Layer-by-Layer Construction of Metal Oxide and Nitride Thin Films by Non-Hydrolytic Condensation

Susannah L. Scott*

Departments of Chemical Engineering and Chemistry, University of California at Santa Barbara,
Santa Barbara CA 93106-5080 USA

This is an abstract for a presentation given at the
11th Foresight Conference on Molecular Nanotechnology


Molecular layer epitaxial growth of transition metal-containing thin films is usually based on hydrolysis of a grafted layer to create additional sites for condensation of the subsequent layer. In order to avoid the complex hydrolysis reactions which lead to uncontrolled aggregation of metal sites, we have designed molecular layer growth reactions based on non-hydrolytic condensations. In some cases, these reactions are spontaneous as well as self-limiting, as in the reaction of M(OR)4 (M is Ti, Zr) with the surface hydroxyls of silica, which results in formation of oxo-bridged sites with elimination of ROH + R(-H), or the analogous reaction of Mo(NEt2)4 which yields imine-bridged sites via formation of HNEt2 + HN(CHCH3)Et. In other cases, the condensation can be induced either by (a) thermolysis, or (b) ligand metathesis. An example of the former is the thermally-induced (100°C) C-H activation of surface dialkylamido complexes of titanium to generate imine and imido sites which bind Ti(NR2)4. The latter include reactions of surface metal chlorides with alcohols, creating metal alkoxo sites which condense further with metal chlorides by elimination of RCl. This approach has allowed us to prepare metal oxide and nitride overlayers of atomically precise composition and thickness and which presumably can be made to reproduce the morphology of any siliceous substrate.

Abstract in Microsoft Word® format 20,806 bytes

*Corresponding Address:
Susannah L. Scott
Departments of Chemical Engineering and Chemistry, University of California at Santa Barbara
Santa Barbara CA 93106-5080 USA
Phone: (805) 893-5606 Fax: (805) 893-4731


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