1. Emergence of Nanowires

The design, development and understanding of synthetic materials, with at least one dimension below 100 nm, have been driving a broad range of research in the scientific community for a number of years given the potential of such materials to substantially impact many areas of science and technology. In particular, one-dimensional nanowires, with diameters reaching to the molecular or quantum regime, have been a focus of research over the past two decades. The underlying principles for synthesis of one-dimensional materials have been investigated in different contexts for almost half a century ago, although significant challenges existed in developing the critical understanding to control (i) diameters to the deep nanoscale dimensions as well as (ii) structure and composition in the axial and radial coordinates as necessary for the synthesis of materials with designed and tunable functionality. In this chapter, the emergence of the nanowire research platform is introduced, including the concept and importance, synthetic challenges and initial design, and the development of vapor-liquid-solid crystal growth mechanism. In addition, other nanofabrication based approaches explored in the early years of this field will be briefly introduced.