Preparation and Raman scattering study of pore arrays on an InP (1 0 0) surface

Straight nanometer-sized pore arrays are formed on an n-InP (1 0 0) surface by electrochemical anodization in HCl-based electrolytes. Raman scattering spectra are measured and compared to those of the bulk InP. Two new peaks around 299 and 304 cm⁻¹ are observed for porous InP. The peak at 299 cm⁻¹ is attributed to a TO phonon mode observable due to a breakdown of polarization selection rule in the case of nanometer-sized crystallites. The peak at 304 cm⁻¹ is suggested to be a surface-related vibration mode. In addition, the Raman signals of the porous InP are intensified up to 20–25 times than that of the bulk InP. The reason for such strong enhancement is not clear and is under further investigation.