Optical properties of lonsdaleite silicon nanowires: A promising material for optoelectronic applications

Lonsdaleite silicon has exhibited a wealth of fascinating properties and is known to have photoluminescence at room temperature. Several researchers have reported the limitations of diamond cubic silicon in the area of optoelectronic devices due to its indirect band gap. Therefore, different phases of silicon are investigated worldwide for the substitute of diamond silicon to overcome its limitation. Recently, it is suggested that lonsdaleite silicon nanowires (SiNWs) can be used as a potential material for optoelectronic applications. Therefore, the optical properties of lonsdaleite silicon nanowires are investigated here by Raman spectroscopy, UV-vis absorption spectroscopy and photoluminescence spectroscopy. Phonon dispersion curve, which has been computed using density functional calculations, is utilized to study the Raman modes of lonsdaleite silicon nanowires. The absorption coefficient of lonsdaleite silicon nanowires shows a remarkable enhancement in comparison with that of diamond structured SiNWs. Furthermore, greenish-yellow photoluminescence is also observed here from lonsdaleite silicon nanowires.