Self-assembly Nanostructure and Lithography Prepared by Thu Nguyen

Self-Assembled Nanostructures Self-assembled epitaxical quantum nanostructures are a class of nanostructures created by exploiting naturally occurring forces between the constituents, usually atoms and/or molecules, and a crystalline substrate such that the atoms of the resulting nanostructure have a definite spatial relationship with the underlying substrate atoms. Since the nanostructures form during a film growth process, rather than through post-growth patterning and etching on the nanoscale, these have been dubbed self-assembled (or self-organized) nanostructures.

The directed self-assembly process can produce large, virtually perfect arrays of bent lines at the nanoscale. Such arrays could form the basis of nanoscale electronic devices.

Electron-beam Lithography The technique in brief consists of scanning a beam of electrons across a surface covered with a resist film sensitive to electrons, thus depositing energy in the desired pattern on the resist film. Write lines with widths of only a few nanometers in a layer of photoresist on a silicon substrate. Electron beams do not cause blurring of the edges of features because at atomic scale they don’t diffract. Can be done at nano-scale, as compared to photolithography, which is done at micro-scale. Expensive and impractical for large-scale manufacturing because the beam of electrons is needed to fabricate each structure, thus the process can be done with one line at a time.

Applications: Application areas of e-beam lithography span a wide range from cryo-electric devices, opto-electronic devices, quantum structures, transport mechanism studies of semiconductor/superconductor interfaces, microsystem techniques, optical devices. The use of electron-beam lithography on pentacene and poly(3-hexylthiophene) field-effect transistor to achieve device isolation and enable the realization of nanoscale organic circuits. Can be used in the fabrication process by soft lithography.

Soft Lithography Soft lithography uses an elastomeric mold to shape soft materials. This technique has been recently developed as a tool for micro- and nano-fabrication (optoelectronic components)