Evaluation of morphology and crystal structure of Si nanowires prepared by singlestep metal assisted etching

The macro and micro morphology, and the crystal structure of Si nanowires prepared by singlestep catalytic metal assisted etching were investigated. Here, we prepared the Si nanowires by metal assisted etching with electroless-deposited Ag catalyst on Si (100) substrate. We used mixture of silver nitrite and hydrofluoric acid as a plating bath of Ag, as well as etching solution of Si. The morphology and crystalline structure of the nanowires as a function of concentration of silver nitrite in etching bath were investigated by SEM and cross-sectional TEM observations. With increasing concentration of the silver nitrite in the etching solution, the surface of nanowires tends to be porous structure with very fine pores of a few nm (porous Si nanowire). When concentration of silver nitrite is low, single crystal Si nanowires with a smooth surface without pores were observed. The porous Si nanowires consisted of the nano scaled crystals and partially amorphous Si nears its surface.