Solidification microstructure of Bridgman-grown Si-TaSi₂ eutectic in situ composite

Directionally solidified Si-TaSi₂ eutectic in situ composite was fabricated by Bridgman growth technique with a high temperature gradient. The microstructure and solid/liquid interface morphology evolvement were systematically investigated. The grown Si-TaSi₂ presents typical semiconductor-metal eutectic structure with the TaSi₂ regularly and uniformly embedded into Si matrix. As the solidification rate increases from 6 to 150 μm/s, the fiber diameter and eutectic spacing rapidly decrease, whereas the rod density increases. The eutectic spacing and solidification rate obey the relationship of λV^0.53=73.7 μm^1.53/ s^0.53. Under the optimal solidification parameter (V=100 μm/s), the fiber diameter is 1.37 μm, average eutectic spacing is 3.83 μm, and rod density is 3×10⁶ rod/cm², which well satisfy the requirement of Spindt field emission arrays. Furthermore, the solid/liquid interface undergoes an evolvement of planar-shallow cell-cell with the increase of solidification rate.