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 50min), sharp TaSi₂ tips with curvature radius of 18nm 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.