Characterization of Germanium Nanocrystallites Grown on SiO2 by a Conductive AFM Probe Technique

Abstract

Hydrogenated germanium films were fabricated in the thickness range of 7-98 nm on SiO 2 at 150°C by an rf glow discharge decomposition of 0.25% GeH 4 diluted with H 2 , and the nucleation and growth of Ge nanocrystallites were measured from topographic and current images simultaneously taken by a conductive AFM probe after Cr contact formation on films so prepared. We have demonstrated that current images show fine grains in comparison with topographic images and the lateral evolution of the Ge grains with progressive film growth. The contrast in current images can be interpreted in terms of the difference in electron concentration between nanocrystalline grains and their boundaries.