Patterning nanoporous materials

Nanomaterials and Device Fabrication by Nanochemistry

The activity consists in the fabrication of complex hierarchical nano and micro nanostructured materials from combined approaches bottom-up / top-down.

Patterning Metal Organic Frameworks colloids

In this work we describe a soft-lithographic approach to fabricate sub-micrometer MOF- based 2D photonic structures. Nanometric Zeolitic Imidazole Framework material ZIF-8 (zinc) was chosen as the sensible MOF material because of its chemical stability and its vapor selective adsorption properties. Two different systems were fabricated: nanopatterned colloidal ZIF-8 homo- and ZIF-8/TiO2 hetero-structures. Several features (stripes, squares, etc.) with dimension as small as 200 nm, were replicated on different substrates such as silicon, flexible plastics and even on aluminum cans, over relatively large surfaces (up to 1 cm2).

 

Making photonic sensors out of cracks!

Formation of cracks in colloidal films is generally considered as major drawback for the fabrication of photonic devices. However, in controlled conditions the controlled drying of colloidal droplets results in the formation of parallel periodic cracks oriented by the evaporation front-line as observed in mud’s cracks.
In this contribution, we demonstrate for the first time that colloidal photonic devices can be fabricated by engineering cracks. In particular Metal-Organic Framework colloidal films (sub-50 nm MIL 101 or ZIF-8) can be crack-patterned during dip-coating deposition where the crack propagation is oriented by the evaporation front.

Have a look to the crack self-assembly mechanism here!


Patterning Sol-Gel based Materials

 

 Here some examples:

(a) UV or X-ray Lithography, (c) soft Nano Imprinting Lithography and (e) Reactive Ion Etching applied to inorganic nanostructured coatings. SEM images of (b) nano-in-micro titania patterned surface by DXRL, (d) nano-imprinted mesoporous titania by s-NIL and (f) silicon nanowells from RIE though a self-assembled mask. 

Degassing-Assisted Patterning
A simple, device-free technique called ” Degassing-Assisted Patterning” was developed in collaboration with Dr. A. Cattoni. This strategy allows imprinting sol-gel based materials at the sub-100 nm scale. The hierarchical materials can find application in photonics or controlled wetting.
Self-assembled sol-gel mask for nano lithography
This work aims extending and diversifying the toolbox of nano fabrication methods by using bottom-up approaches.The projet consists in preparing ultra-thin self-assembled nanoperforated titanium calcium oxide  reactive nanomasks for selective dry etching of silicon. This  nanomask is composed of TiO2 in which up to 50% of Ti was replaced by Ca (CaxTi(1−x)O(2−x)). The system was prepared by evaporation induced self-assembly of dip-coated solution of CaCl2, TiCl4 and poly(butadiene-block-ethylene oxide). The mask exhibits enhanced selectivity by forming a CaF2 protective layer in the presence of a chemically reactive fluorinated plasma. In particular, ordered nano-arrays of dense Si pillars, or deep cylindrical wells can be formed. Both wells and pillars were formed by tuning the morphology and the homogeneity of the deposited mask.  Its combination with reactive ion etching constitutes one of the first examples of what can be achieved when sol–gel chemistry is coupled with top–down technologies.