Crystalline–amorphous core–shell silicon nanowires (SiNWs) grown separately on glass and stainless steel substrates were investigated by Raman spectroscopy. Raman spectra confirmed the presence of crystalline and amorphous silicon phases in both samples. With respect to bulk silicon, the crystalline Raman peaks for the nanowires grown on a glass substrate showed much larger red shift and spectral broadening as compared to that of the nanowires grown on stainless steel. The Raman shift was attributed to local heating which was further confirmed by the reduction in red shift of the Raman spectrum at lower incident powers for both samples. For a low input power of 0.8 mW, the nanowires grown on stainless steel showed no shift in the first order Raman peak as compared to bulk silicon, however a small spectral broadening was still observed.
TEM images for the nanowires grown on steel substrate.