Preparation, microstructure characterisation and corrosion behaviour of directionally grown TaSi_2 fibre arrays with sharp tip fabricated by selective wet etching

摘要

Directionally solidified Si-TaSi_2 eutectic composite is selectively etched to fabricate well aligned TaSi_2 tip array for field emission application. The effect of etching parameters on TaSi_2 tip structure, and its corrosion behaviour in HNO_3/HF solution are investigated. At the optimised condition (HNO_3/HF = 5 for 50 min), sharp TaSi_2 tips with curvature radius of 18 nm and homogenous distribution are obtained, which greatly improves the figure of merit associated with field emission current. The TaSi_2 fibre presents smaller dissolution rate in the HNO_3/HF solution than Si matrix. The formation mechanism of etching pit on the Si matrix surface is also discussed.