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Nanomaterials, Nanoelectronics, and Nanofabrication Technology
Published in Michael Olorunfunmi Kolawole, Electronics, 2020
Carbon is a group 14 element that resides above silicon in the periodic table, as seen in Figure 1.2, Chapter 1. Like silicon and germanium, carbon has four electrons in its valence shell. In its most common state, carbon is an amorphous non-metal like coal or soot. In a crystalline state, that is, in tetrahedrally bonded state, carbon becomes diamond that is an insulator with a relatively large bandgap. However, when carbon atoms are arranged in crystalline structures composed of hexagonal benzene-like rings, they form a number of allotropes that offer exceptional electrical properties. Carbon is the substance with the greatest number of allotropes. Graphite, charcoal, and diamond are all allotropes of carbon. Carbon possesses allotropes most radically different from one another, ranging from soft to hard, opaque to transparent, abrasive to smooth. These allotropes include the amorphous carbon allotrope, carbon nanofoam, carbon nanotube, graphite, and ceraphite allotrope, to name a few. For the replacement of silicon in future transistor channels, the two most promising of these allotropes to date, as noted in the literature, are graphene and carbon nanotubes.
Future of photovoltaic materials with emphasis on resource availability, economic geology, criticality, and market size/growth
Published in CIM Journal, 2023
G. J. Simandl, S. Paradis, L. Simandl
Silicon is a nonmetallic element in Group 14 (carbon family) of the periodic table with atomic number 14. It is the second most abundant element in the earth’s crust by weight (31.14%) after oxygen (Rudnick & Gao, 2014). It can be found in a wide variety of minerals and elemental compounds. Silicon dioxide (SiO2) or silica is one of the most common compounds, forming all quartz polymorphs and varieties, agate, opal, and chert. Quartz is one of the main rock-forming minerals and the main constituent in high-purity sand, sandstone, and quartzite. It is commonly the main constituent of cores of pegmatites and mineralized or barren hydrothermal veins. Silica materials are available on all continents and satisfactory for most common applications, including ferrosilicon and metallurgical-grade silicon (MG-Si). However, in most cases, the silica content of these rocks is too low and the impurities content is too high for direct transformation to solar- or electronic-grade Si.