Controlling the formation of endotaxial CoSi₂ nanowires and nanodots on Si(001)

We investigated the selective formation and growth of endotaxial CoSi₂ nanowires and nanodots on Si(001) through reactive deposition endotaxy using substrate temperature control. By studying the nucleation behaviour and change in number densities (N) of the nanostructures in the pre-coalescence regime using scanning tunnelling microscopy (STM), the probability of nucleating flat-type nanodots or ridge-type nanowires was found to exhibit an Arrhenius-like dependence with growth temperature. Considering the surface distribution of cobalt adatoms in the steady growth regime, ridge-type nanowires are found to have a lower energy barrier (E_R) compared to flat-type nanodots (E_F) by 0.51 ± 0.08 eV. In other words, it is endotaxially and kinetically more favourable to nucleate and grow ridge-type nanowires over flat-type nanodots at lower growth temperatures. As the temperature increases, the distribution between ridge-type and flat-type islands becomes more balanced, with a trend suggesting that flat-type islands become increasingly favourable for nucleation and growth at higher temperatures.