Surface chemistry controlled diameter-modulated semiconductor nanowire superstructures

The authors demonstrate that semiconductor nanowire diameter can be rationally controlled as a function of axial position during vapor–liquid–solid synthesis. Such nanoscale structural tuning is achieved with a “molecular resist,” specifically tetramethyltin, that adsorbs on the nanowire sidewall and restricts radial deposition without destabilizing the growth front. The temporal modulation of tetramethyltin delivery during Ge nanowire growth yields user-programmable diameter-modulated superstructures with sub-100 nm periodicities. The authors also investigate the effect of Sn accumulation in the growth catalyst and propose a second-order kinetic rate law that accurately predicts changes to nanowire axial growth rate.