Facile morphological control of single-crystalline silicon nanowires

► The morphology of SiNWs is facilely controlled in a chemical etching method. ► The vertically-, slantingly-aligned and zigzag SiNW arrays are synthesized. ► Their surfaces can be controlled to be smooth and rough, with or without mesopores. ► The formation mechanisms of various morphologies of SiNWs are discussed.