Nanodot to Nanowire: A strain-driven shape transition in self-organized endotaxial CoSi2 on Si (100)

TL;DR

This paper describes a strain-driven shape transition in self-organized CoSi2 islands on Si (100), leading to nanowire formation with potential applications in nanoelectronics.

Contribution

It reveals a critical size-induced shape transition from square to rectangular nanostructures, resulting in nanowires with high aspect ratios and Schottky diode behavior.

Findings

Square islands grow up to 67 nm before transitioning

Larger islands form nanowires with aspect ratios up to 20:1

Nanowires exhibit Schottky diode characteristics

Abstract

We report a phenomenon of strain-driven shape transition in the growth of nanoscale self-organized endotaxial CoSi2 islands on Si (100) substrates. Small square shaped islands as small as 15\times15 nm2 have been observed. Islands grow in the square shape following the four fold symmetry of the Si (100) substrate, up to a critical size of 67 \times 67 nm2. A shape transition takes place at this critical size. Larger islands adopt a rectangular shape with ever increasing length and the width decreasing to an asymptotic value of ~25 nm. This produces long wires of nearly constant width.We have observed nanowire islands with aspect ratios as large as ~ 20:1. The long nanowire heterostructures grow partly above (~ 3 nm) the surface, but mostly into (~17 nm) the Si substrate. These self-organized nanostructures behave as nanoscale Schottky diodes. They may be useful in Si-nanofabrication and find potential application in constructing nano devices.