铜辅助化学腐蚀条件对多孔硅的影响

Abstract

以铜(Cu)作为催化剂,采用两步化学腐蚀法成功制备了微纳米多孔硅(PS)。本文方法成本低廉、操作简易。系统研究了腐蚀液中H_2O_2浓度、Si衬; 底掺杂浓度、腐蚀液温度和腐蚀时间对PS表面形貌和腐蚀深度的影响,并得到最佳制备参数。高、低掺Si衬底所采用的最佳配比腐蚀液中的H_2O_2浓度分; 别达到0.70mol/L和0.24mol/L。在25℃腐蚀液中,腐蚀2h得到约200nm深的纳米级孔洞,其表面反射率在宽波段内降低到5%以下;而; 在50℃腐蚀液中,经过2~4h的腐蚀,可得到14~41mum深的结构稳定的微纳米级孔洞。文中还对Cu辅助腐蚀与其他金属辅助腐蚀(MACE)作了对; 比,分析了Cu辅助腐蚀获得锥状孔洞的原因和机理。

Porous silicon with micro-nano sizes has been prepared by the; metal-assisted chemical etching approach with Cu nanoparticles as the; catalyst agents.This method has the advantages of low cost and simple; operation.The effects of the preparation condition on the morphologies; and etching depth of the porous structures is discussed,such as the; concentration of H_2O_2,the doping level of silicon substrate, the; temperature of etching solution and the etching time.An optimal etching; condition is obtained,the concentration of H_2O_2in the reactant is more; than 0.70mol/L for highly doped silicon substrate,and more than; 0.24mol/L for lightly doped silicon substrate.Nano porous structures; with layer thickness about 200nm are obtained after etching for 2hat the; temperature of 25℃.The average surface reflectivity of the prepared; nanostructures is under 5%for the wide band.While at the optimal; temperature of 50 ℃,stable structures of micro-nano porous silicon with; depth about 14-41mum are achieved after etching for about 2-4h.The; formation mechanism of the surface morphology of the Si wafers under; different reactant concentrations can be explained with the hole; injection model.The action of Cu and other metals on the etching is; studied,and the formation of the pores with cubic cone shape is also; analyzed.