Fabrication of Lotus-type Porous Silicon by Unidirectional Solidification in Pressurized Hydrogen Atmosphere

摘要

Lotus-type porous silicon is a promising micro-channel heat sink material in cooling of high powered electronic devices.Lotus-type porous silicon with elongated pores has been successfully fabricated by unidirectional solidification at different velocities.The average pore diameter and inter-pore spacing all increase whether along the height direction of the ingot or with increasing the thickness of graphite sheet (lower solidification velocity).The calculated porosity is in good agreement with the experimental results which almost keep as constant at different solidification velocities.The penetration ratio or the pore length increases with decreasing solidification velocity.The bigger pores are more likely to grow longer than smaller ones.In addition,the microstructure observation shows that the pores mostly distribute at the grain boundaries.