Preparation, microstructure characterisation and corrosion behaviour of directionally grown TaSi2 fibre arrays with sharp tip fabricated by selective wet etching

Directionally solidified Si-TaSi2 eutectic composite is selectively etched to fabricate well aligned TaSi2 tip array for field emission application. The effect of etching parameters on TaSi2 tip structure, and its corrosion behaviour in HNO3/HF solution are investigated. At the optimised condition (HNO3/HF = 5 for 50 min), sharp TaSi2 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 TaSi2 fibre presents smaller dissolution rate in the HNO3/HF solution than Si matrix. The formation mechanism of etching pit on the Si matrix surface is also discussed.