Spectral Anomaly in Raman Scattering from p-Type Silicon Nanowires

Abstract

An anomalous nature of Raman spectral asymmetry has been reported here from silicon nanowires (SiNWs) prepared from a heavily doped p-type Si wafer using a metal induced etching technique. Raman spectra of SiNWs prepared from two p-type Si wafers with different doping levels show different behaviors in terms of asymmetry as characterized by the asymmetry ratio. The SiNWs prepared from high doped p-type wafer show an anomaly in asymmetry in addition to the red shift and broadening of the Raman line shape due to the presence of the “FAno-quaNTUM” (FANTUM) effect. The heavy doping in the wafer provides a continuum of energy states to be available to interact with confined optic phonons which results in electron–phonon interaction. SiNWs prepared from low doped p-type wafer show a red shift and asymmetric broadening due to the quantum confinement effect alone. Careful analysis has been provided to clearly understand the role of Fano and quantum effects in p-type SiNWs with high doping and their relative contr...