Semiconductor Nanowires: Rational Synthesis
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Rational design and synthesis of nanoscale materials is critical to work directed towards understanding fundamental properties, creating nanostructured materials, and developing nanotechnologies. One-dimensional (1D) nanostructures [such as nanowire (NW) and nanotubes] have been the focus of considerable interest because they have the potential to answer fundamental questions about role of dimensionality in physical properties and are expected to play a central role in applications ranging from molecular electronics to scanning probe microscopy probes. To explore the diverse and exciting opportunities in 1D system requires materials for which the chemical composition, diameter, length, electronic, and optical properties can be controlled and systematically varied. To meet these requirements, we have focused our efforts on developing a general and predictive approach for the synthesis of 1D structures, much as molecular beam epitaxy has served as an all-purpose method for the growth of two-dimensional (2D) structures. Specifically, it is important to achieve the ability to design and synthesize rationally NWs with predictable control over the key structural, chemical and physical properties, since such control would greatly facilitate studies designed to understand the intrinsic behavior of 1D structures and to explore them as building blocks for nanoscale electronics. Here, in this article, we review recent advances in rational synthesis of semiconductor NWs. We will first address the key requirement for 1D growth and give a brief overview of various methods towards 1D materials. Subsequently, we will focus our discussion on growth of a broad range of semiconductor NWs via a metal-nanocluster mediated catalytic growth method based on vapor–liquid–solid (VLS) growth mechanism. Next, we further describe growth of NW materials with controlled physical size including diameter and length. Lastly, we discuss growth of NW heterostructures and superlattices with composition/doping modulation along the axial or radial direction.