Lithography molecular self-assembly

Quantum dots are the engineered counterparts to inorganic materials such as groups IV, III-V and II-VI semiconductors. These structures are prepared by complex techniques such as molecular beam epitaxy (MBE), lithography or self-assembly, much more complex than the conventional chemical synthesis. Quantum dots are usually termed artificial atoms (OD) with dimensions larger than 20-30 nm, limited by the preparation techniques. Quantum confinement, single electron transport. Coulomb blockade and related quantum effects are revealed with these OD structures (Smith, 1996). 2D arrays of such OD artificial atoms can be achieved leading to artificial periodic structures. 

Important techniques for bottom-up nanofabrication include soft lithography and surface self-assembly. Also the use of containers such as carbon nanotubes to confine molecular scale objects in one dimension is a useful tool. 

Nanoscale assembly Self-assembling micellar structures [113,114] Bio-self-assembly and aggregation [115,116] Nanomanipulation [117,118] Soft lithography [119,120] Molecular imprinting [121,122] Layer-by-layer electrostatic deposition [123,124] Chemical vapor deposition [125]... 

Fig. 2 Different paths to obtain hybrid materials from molecular sources. Path A Sol-gel routes (Al conventional route for hybrid nanocomposites, A2 molecularly homogenous hybrids). Path B Assembly of nanobuilding blocks (ANBB), of prefunctionalized or postfunctionalized clusters or nanoparticles. Route C or D involve the use of templates capable of self-assembly, giving rise to organized phases. Path E involves integrative synthesis combining precedent paths from A to D and other processes, such as the use of lithography, casting, organogels or latex beads as templates, controlled phase separations, or external fields. (From Ref. l) (View this art in color at www.dekker.com.)...

Nanocavity electrodes offer particular advantages for molecular detection since the cavity can be easily functionalized, e.g., packed with an enzyme, to create ultralow volume sensors that are mechanically stable under real world conditions. We recently described the use of nanosphere lithography, combined with self-assembly of a blocking surface active agent to create recessed nanocavity electrodes whose radius can be repro-ducibly controlled from 100 nm up to several... 

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