Band structures, nanowire properties

This chapter summarizes the main theoretical approaches to model the porous silicon electronic band structure, comparing effective mass theory, semiempirical, and first-principles methods. In order to model its complex porous morphology, supercell, nanowire, and nanocrystal approaches are widely used. In particular, calculations of strain, doping, and surface chemistry effects on the band structure are discussed. Finally, the combined use of ab initio and tight-binding approaches to predict the band structure and properties of electronic devices based on porous silicon is put forward. 

Nanowire systems have attracted a great deal of attention recently due to their technological potential They are of fundamental interest because they exhibit unique quantum confinement effects. In this article, advances in the fabrication of nanowires via template-assisted and laser-assisted approaches are reviewed. The structure and characteristics of different nanowire systems are discussed. To understand and predict the unusual properties of nanowires, we have developed a generalized theoretical model for the band structure of these onedimensional systems. A unique semimetal-semiconductor transition that occurs in bismuth nanowires is described. Transport measurements on bismuth and antimony nanowires illustrate that these novel materials are very different from their bulk counterparts. A transport... 

The electronic states of nanowire systems exhibit a very different spectrum from that of bulk materials. In order to understand their unique electronic properties, we have modeled the band structure of these one-dimensional systems. 

The transport properties of nanowires are of technological importance and have attracted significant attention in the recent years. Band structure gives simple solution to the analysis of the ballistic transport of periodic nanowires because the number of the bands crossing the Fermi surface is equal the number of quantum of conductance. However, the situation in nanocontacts is more complicated [112],... 

Recently, photoluminescence properties of boron carbide nanowires were being studied and reported. Photoluminescence spectrum of a thin film made out of B4C nanowires exhibited a broad band at 638 nm, which strongly suggests the potential application of boron nanowires in visible optical devices. Nonetheless, nanowire and nanorod structures based on boron carbide find their application in different areas, including field emission devices and thermoelectric energy converters, neutron adsorbent in nuclear industries, and especially in composite materials as reinforcing agents. ... 

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