Confined Sol-Gel route to epitaxial Octahedral Molecular Sieve nanowires on silicon
Résumé
Manganese oxides octahedral molecular sieves (OMS) with mixed-valence frameworks have been widely used as bulk material in catalysis, semiconductor industry, and batteries. Monolithic direct integration of OMS with vertically oriented crystals on a semiconductor platform is challenging due to difficulties on preserving epitaxy, crystalline phase, and composition. Here, we developed a new strategy to produce vertical epitaxial single crystalline OMS nanowires with tunable composition and enhanced ferromagnetic properties on Si substrates by using a chemical solution deposition approach [1]. The nanowire growth mechanism involves the use of track-etched nanoporous polymer templates combined with the controlled growth of α-quartz thin films at the Si surface, which allowed OMS nanowires to stabilize and crystallize. α-quartz layers were obtained by thermally activated devitrification of the native amorphous silica surface layer assisted by a heterogeneous catalysis driven by alkaline earth cations (Sr2+, Ba2+ or Ca2+) present in the precursor solution [2]. Therefore, the combination of soft-chemistry and epitaxial growth opens new opportunities for the effective integration of novel technological functional tunneled complex oxides nanomaterials on Si substrates [3]. [1] A. Carretero-Genevrier et al. Chem.Soc.Rev. 10.1039/C3CS60288E (2013) [2] A. Carretero-Genevrier et al. Science 340, 827 (2013) [3] A. Carretero-Genevrier et al. Chem.Mater. 10.1021/cm403064u (2013)