Effect of Corrosion Time on Porous Layer Morphology and Polycrystalline Silicon Properties

Porous silicon layer was prepared on the surface of polycrystalline silicon by chemical etching. The surface morphology, polycrystalline silicon minority carrier lifetime and resistivity of the porous silicon layers etched for different times were investigated after impurity removing by external gettering heat treatment. The results show that with the prolongation of etching time, the surface morphology of porous silicon layer was different, the pore diameter of the porous silicon got large gradually, the minority carrier lifetime and the resistivity were enhanced too. Some partial areas of porous silicon collapsed and the wall of holes turned thinner after etching for 14 min. The minority carrier lifetime and the resistivity of porous silicon reached 0.98 μs and 0.16 Ω·cm respectively after etching 11 min and gettering treatment at 850 ℃.