Role of the vacuum pressure and temperature in the shape of metal Zn nanoparticles

Abstract

Zinc (Zn) nanoparticles were fabricated by the high-vacuum thermal evapouration technique. The vacuum pressure was modified from 10-6 to 15 Torr and the substrate temperature was increased from room temperature to 100°C in order to evaluate the changes in the morphological and structural characteristics of the Zn nanoparticles. Well-faceted hexagonal disk shaped nanoparticles were formed at a vacuum pressure of 10-6 Torr with the substrate kept at room temperature. Aggregation and surface irregularities at the edges of the hexagonal nanodisks were observed with further increases in the vacuum pressure. The nanoscale characteristics of the nanodisks were lost at a vacuum pressure of 10-6 Torr and heating the substrate at 100°C. The nanodisks were transformed into Zn wires at a vacuum pressure of 15 Torr with a substrate temperature of 100°C. It is suggested that the initial stages of the growth of the Zn wires are governed by the agglomeration of the Zn nanodisks since the structure of the wires was observed to be composed by stacked nanodisks.