电化学制备多孔硅的工艺对其形貌的影响

Preparation and morphology influence of porous silicon by electrochemical etching conditions

采用电化学腐蚀方法,将不同比例的乙醇和质量分数为40%的氢氟酸混合,并以此混合液为腐蚀液,在光照条件下,制备了N型轻掺杂的多孔硅。讨论了不同电化学腐蚀条件对多孔硅结构的影响。研究表明,电流密度、腐蚀时间和氢氟酸质量分数越大时,制备的多孔硅越深,孔径也越大,当以上三者数值过大时会导致多孔硅机械强度急速减弱。由表面形貌可知,当多孔层孔径小于500nm时其机械强度良好,当孔径超过这一阈值尤其是大于800nm时,多孔层骨架则极易断裂。

By using electrochemical etching,aporous structure on N-type doped silicon was prepared in a mixture of ethanol and hydrofluoric acid(the mass fraction is 40%)with light irradiation.The influences of different electrochemical etching conditions on the structure of porous silicon were discussed.The studies show that any increasing of the current density,etching time or HF mass fraction would enlarge the aperture as well as the depth of the porous.When these three parameters exceed the thresholds,the mechanical strength of the porous silicon becomes extremely weak.By the surface topography,when the aperture size is smaller than 500 nm,the porous exhibit quite high mechanical strength,but when the size is larger than 500 nm,particularly larger than 800 nm,the fracture of the skeleton of the porous layer easily occurs.