Integrating functional oxide nanomaterials in silicon technology by chemical solution deposition
Résumé
In the past years, great efforts have been devoted to combine the functionality of oxides with the performances of semiconductor platforms for the development of novel and more efficient device applications. However, further incorporation of functional oxide nanostructures as active materials in electronics critically depends on the ability to integrate crystalline metal oxides into silicon structures. In this regard, the presented work takes advantage of all the benefits of soft chemistry to overcome the main challenges for the monolithic integration of novel nanostructured functional oxide materials on silicon including (i) epitaxial piezoelectric α-quartz thin films with tunable textures on silicon wafers [1] and (ii) 1D single crystalline phases of manganese oxide based nanostructures with enhanced ferromagnetic properties on silicon wafers that share common growth mechanisms [2]. Importantly, these mechanisms are governed by a thermally activated devitrification of the native amorphous silica surface layer assisted by a heterogeneous catalysis under atmospheric conditions driven by alkaline earth cations present in the precursor solution. Quartz films are made of perfectly oriented individual crystallites epitaxially grown on (100) face of Si substrate with a controlled porosity after using templating agents. Moreover, a quantitative study of the converse piezoelectric effect of quartz thin films through piezoresponse force microscopy shows that the piezoelectric coefficient d33 is between 1.5 and 3.5 pm/V which is in agreement with the 2.3 pm/V of the quartz single crystal d11. Manganese based molecular sieve nanowires growth mechanism, involves the use of track-etched nanoporous polymer templates combined with the controlled growth of quartz thin films at the silicon surface, which allowed OMS nanowires to stabilize and crystallize. All together, the methodology presented here exhibits a great potential and offers a pathway to design novel oxide compounds on silicon substrates by chemical routes with unique optical, electric, or magnetic properties. [1] A.Carretero-Genevrier et al. Science 340, (2013) 827 [2] A.Carretero-Genevrier et al. Chem.Soc.Rev. (2014) DOI: 10.1039/C3CS60288E,