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 (ER) compared to flat-type nanodots (EF) 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.