Synthesis of free-standing, curved Si nanowires through mechanical failure of a catalyst during metal assisted chemical etching

The fabrication of orderly arrays of free-standing, curved Si nanowires over large areas (1 cm x 1 cm) was demonstrated by means of interference lithography and intentional mechanical failure of a perforated Au catalyst during metal assisted chemical etching. Photoresist microgrooves were deposited on the perforated Au film to cause uneven etching which resulted in the build-up of bending stresses in the Au film to the point of catastrophic failure. By considering the initial positions of the holes in the perforated Au film relative to the photoresist constraints, the precise location of the fracture can be predicted using simple beam mechanics. Therefore, the type of curved nanowires obtained can be designed with a high degree of reliability and control. Four distinct types of nanowire arrangements were demonstrated for this study.