Figure 6 .
Raman spectra of porous Si. Raman spectra (a), (b), (c) and (d) were obtained from samples 1, 2, 3 and 4, respectively. The presence of amorphous Si in the etched PS can be confirmed from the transverse optical (TO) mode at 480 cm−1 in the spectra; longitudinal optical (LO), longitudinal acoustical (LA) and transverse acoustical (TA) modes are located at 375, 310 and 150 cm−1, respectively.
Kim and Cho Nanoscale Research Letters 2012 7:408 doi:10.1186/1556-276X-7-408