Advances of SiOx and Si/SiOx Core-Shell Nanowires

Abstract

Nanotechnology can be defined as the design, construction and utilization of functional materials with at least one of the dimension measured is in nano-scale to exploit the new properties and phenomena developed at that scale. These nanomaterials exhibit new and improved physical, chemical and biological properties, phenomena and processes due to the variation of wavelike properties of electrons inside matter as the size of matter is reduced and the electrons are confined. Nanowires, one of the one-dimensional nanostructures, are wire-like structure that has diameter less than 100 nm. Single crystal nanowires grow along a specific axial direction though their side surfaces may not be well defined. The cross-section of the nanowires may either be round, hexagonal or polyhedron depending on the crystallography of the material (Lieber & Wang, 2007). The length of nanowires can vary from few hundred of nanometers to micrometer and even millimeters. In this chapter, we review advances of SiOx nanowires and Si/SiOx core-shell nanowires. Nanowires, which are one form of one-dimensional nanostructures, have been used as versatile building blocks in the miniaturization of electronic and optoelectronic devices (Li et al., 2005). Various materials have been synthesized in the form of nanowires, such as silicon, germanium, gallium nitride, gallium arsenide, and silicon carbide (Spanier, 2006). Thus, it is important to understand properties, applications and synthesis methods of the nanowires so as to be able to produce nanowires with well-controlled properties and dimensions to be incorporated into electronic devices. Here in this review, properties, applications and how SiOx nanowires and Si/SiOx core-shell nanowires are made are discussed in the following sections. Section 2 gives a brief discussion on the SiOx nanowires. Section 3 discusses the properties that enable SiOx nanowires to be successfully used in different applications. Section 4 gives a short review on the potential applications of SiOx nanowires. Section 5 reviews the different methods used to synthesize the nanowires, which also includes their phenomena, techniques and mechanism. Section 6 gives a brief discussion on Si/SiOx core-shell nanowires. Section 7 discusses the important properties of Si/SiOx core-shell nanowires that are linked to their potential applications. Section 8 reviews the different methods used to synthesize the core-shell nanowires. Finally, section 9 concludes by a short summary.