Structure and resonant characteristics of amorphous carbon pillars grown by focused-ion-beam-induced chemical vapor deposition

The structure and Young's modulus of amorphous carbon pillars were studied using transmission electron microscopy and mechanical vibration. The carbon pillars were grown by Ga+ focused-ion-beam-induced chemical vapor deposition (FIB-CVD) with phenanthrene gas as a precursor. The pillar had a shell structure comprising a Ga-rich core of about 40nm diameter surrounded by an amorphous carbon shell having a small degree of Ga incorporation. The Young's modulus of the pillars increased up to 600GPa with decreasing growth rate, and the quality (Q) factors evaluated exceeded 1200. Heat treatment of the pillar segregated the Ga droplets at the surface, and Ga was evaporated by annealing at 700degreesC. The Young's modulus, however, decreased by about 10% after such annealing.