Growth of randomly oriented single-crystalline tin (IV) oxide nanobelts: control on the predominant crystalline growth axis.

One-dimensional nanobelts of tin (IV) oxide are synthesized by using a newly introduced catalyst-assisted pulsed laser deposition method along two growth directions of [010] and [101]. An ex situ mask-induced growth gradient technique is employed to investigate the growth evolution of the nanobelts on oxidized-Si, H-terminated Si, and Al2O3(0001) substrates by helium ion microscopy, which reveals four stages of growth including catalyst detachment, horizontal nanorod growth, deflection, and the final nanobelt growth. X-ray diffraction and transmission electron microscopy studies show that in spite of the deflections and changes in the growth direction, the nanobelts have, remarkably, maintained their single-crystalline structure throughout the growth by only changing their crystalline growth axis. This has enabled us to influence the preferred growth axis by establishing a crystalline relation between the nanobelts and an appropriate substrate that pins the nanobelts in the initial growth stage. This growth control provides an important means to selectively promote growth of the predominant side planes of the nanobelts, which can then be separated for appropriate applications based on the different growth kinetics of [010] and [101] growth direction.