化学刻蚀法制备多孔硅的表面形貌研究

Morphological studies of porous silicon surface formed by chemically etching

应用各种表面形貌分析方法如SEM、TEM、AFM等,通过对用化学刻蚀法形成的多孔硅进行表面形貌分析,发现由于横向腐蚀比较严重而使多孔硅层在达到一定深度后就会自动脱落。腐蚀中由于大量H2的析出,对硅晶体产生巨大的应力,这些应力使硅在比较脆弱的晶粒边界或缺陷处产生微裂纹,多孔硅就从这些地方开始和生长。

In terms of scanning electron microscope(SEM), transmission electron microscope(TEM) and atom force microscope(AFM), etc., the surface morphology of porous silicon, formed by chemically etching, was studied. It was shown that the porous silicon layer will be broken off after reaching a certain depth because of the horizontal corrosion. A large stress was formed in the Si substrate because of appearance of lots of H_2 gas. The stress make the microcracks at the brittle crystal boundaries. The porous silicon was formed between microcracks.