Ge Nano-Heteroepitaxy: From Nano-Pillars to Thick Coalesced Layers

Ge epitaxy on nanometer-size Ge pillars was studied in a 300 mm industrial Reduced Pressure-Chemical Vapour Deposition tool. A patterning scheme based on diblock copolymer lithography was used to fabricate honeycombed nanometer-sized Si templates for the hetero-epitaxy of Ge nano-pillars. It was highly selective and uniform at 600°C. Thick Ge layers were then grown with a low temperature/high temperature approach on Ge nano-pillars and characterized by Atomic Force Microscopy, X-Ray Diffraction and cross-sectional Transmission Electron Microscopy. A degraded surface morphology, with otherwise similar structural properties was obtained for 2D Ge layers grown on Ge nano-pillars compared to growth on bulk Si. Defects such as stacking faults and twins also formed during the coalescence process.