Well controlled assembly of silicon nanowires by nanowire transfer method

Abstract

Efforts to date in silicon nanowire research have primarily focused on the nanowire synthesis and the demonstration of individual nanowire-based devices exhibiting interdisciplinary potential spanned from electrical (Duan et al 2003 Nature 425 274–8; Cui and Lieber 2001 Science 291 851–3; Morales and Lieber 1998 Science 279 208–11) through biomedical applications (Cui et al 2003 Science 293 1289–92; Zheng et al 2005 Nature Biotechnol. 23 1294–301). However, the realization of integrated nanowire devices requires well ordered assembly of a silicon nanowire (Huang et al 2001 Science 291 630–3; Whang et al 2003 Nano Lett. 3 1255–9) as well as simple and cost effective fabrication. Here we describe a simple fabrication scheme and a large-scale assembly of silicon nanowires by combining top-down fabrication with nanowire transfer onto another insulator substrate for device manufacture. Our innovative fabrication method enables us to obtain well defined silicon nanowires as a freestanding bridge structure with a diameter of 20–200 nm and a length varying from 5 to 100 µm using micro-machining processes. Direct transfer of the freestanding nanowires simply provides large-scale assembly of silicon nanowire on various substrates for highly integrated devices such as high-performance thin-film transistors (TFTs) (Duan et al 2003 Nature 425 274–8; Ishihara et al 2003 Thin Solid Films 427 77–85) and nanowire-based electronics (Cui and Lieber 2001 Science 291 851–3). Electrical transport properties of the transferred silicon nanowire were also investigated.