Fabrication of germanium nanowires by oblique angle deposition

Abstract

In this work, the effects of flux angle, substrate temperature and deposition rate on obliquely deposited germanium (Ge) films have been investigated. We observed that the porosity of the film increased as the flux angle became more oblique. It was also possible to obtain polycrystalline Ge films at a substrate temperature of 200°C when deposition was performed using an oblique angle of 87° as compared to normal incident deposition. Raman spectroscopy results indicated that a higher substrate temperature during deposition led to an increase in crystallinity of the film. Agglomeration of the Ge film was reduced at a lower deposition rate and it was possible to obtain isolated polycrystalline Ge nanowires when the deposition was carried out with the vapor flux inclined at 87° to the substrate normal for substrate temperatures between 250°C to 300°C and with a deposition rate of 0.2-1.5 Å/s. Subsequent rapid thermal annealing of such nanowires resulted in the formation of facetted crystallites. © World Scientific Publishing Company.