Effect of catalyst shape on etching orientation in metal-assisted chemical etching of silicon

Silicon nanowires with vertical, slanting and zigzag architectures have been fabricated by metal-assisted chemical etching of silicon wafers (n-Si(100), n-Si(111) and n-Si(110)). Two types of zigzag SiNWs with various turning angles (125 degrees and 150 degrees) were obtained via metal-assisted chemical etching using non-Si(100) wafers. The observations reveal that the etching direction of non-Si(100) wafers depends on the shape of the deposited metal catalyst. A proposed mechanism, considering longitudinal and lateral etching, has been developed to explain the etching behaviors.