First-principle study of the structural, electronic, and optical properties of SiC nanowires

Abstract

We preform first-principle calculations for the geometric, electronic structures and optical properties of SiC nanowires (NWs). The dielectric functions dominated by electronic interband transitions are investigated in terms of the calculated optical response functions. The calculated results reveal that the SiC NW is an indirect band-gap semiconductor material except at a minimum SiC NW (n = 12) diameter, showing that the NW (n = 12) is metallic. Charge density indicates that the Si-C bond of SiC NW has mixed ionic and covalent characteristics: the covalent character is stronger than the ionic character, and shows strong s-p hybrid orbit characteristics. Moreover, the band gap increases as the SiC NW diameter increases. This shows a significant quantum size and surface effect. The optical properties indicate that the obvious dielectric absorption peaks shift towards the high energy, and that there is a blue shift phenomenon in the ultraviolet region. These results show that SiC NW is a promising optoelectronic material for the potential applications in ultraviolet photoelectron devices.

Phonon-assisted optical absorption of SiC polytypes from first principles

“…Experimental characterization of its indirect gap and optical absorption in the spectral region between the indirect and direct band gaps already exists ever since the 1960s [22,23]. There has also been a considerable number of theoretical calculations of optical properties for both bulk SiC and nanostructures, however, always focusing on direct transitions [24][25][26][27][28][29][30]. The commonly used theoretical spectroscopy approaches based on the density functional theory lack descriptions of electron-phonon interactions.…”