GavaghanCommunications | Science for scientists. Issue 9, 5.10 - 11.10.10


Item 1, keywords:
single silicon crystal,

Order of magnitude improvement in feature size within homo and heteroepitaxic silicon-silicon and silicon-NiSi single crystal nanostrucures, to achieve features of 30 to 35 nanometre distance.

The researchers created single crystal nanostructures at an order of magnitude 10 times less than in previous efforts. The structures were both like-to-like (homoepitaxic) and like-to-unlike epitaxic (hereoepitaxic) structures. In this case silicon-to-silicon and silicon-to-nickel silicon respectively.

The structures were made by laying amorphous silicon or amorphous nickel silicon onto a surface of crystalline silicon that had been shaped by a laser melting the crystalline silicon base through a template of high molecular weight organic and inorganic polymers. The result was either a base of stand alone crystalline silicon pillars or pillars forming a structure of silicon pillars distributed on a base, depending on the thickness of the base.

Melting the amorphous coatings resulted in a resolidification of the amorphous silicon (or nickel silicon) such that a single crystal structure of matching crystal lattices (epitaxy) was created. In the case of silicon to nickel silicon the latter, being a molecule formed from a transition metal and a group 4B element and having differing valency wave functions, led to a slight lattice misalignment (0.5 to 0.6%) of the silicon and NiSi crystal lattices. But both the homoepitaxy (silicon to silicon) and heteroepitaxy (silicon to nickel silicon) led to single nano structures in which the boundary layers of polycrystallinity that block mobile charge carriers had in large part been removed in addition to being structures with features an order of magnitude less than accomplished previously. Item published by GC 11.10.10.

Based on a paper in Science: Block copolymer, self assembly-directed single-crystal homo and heteroepitaxial nanostructures by Hitesh Arora et al. DOI: 10:1126/science.1193369.

Further basic reading: The crystal structure of solids by PJ Brown and JB Forsyth.

Useful reference reading:
Encyclopaedia of Molecular Biology, Blackwell, 1994, Ed-in-chief Sir John Kendrew.

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