Electroreflectance study of macroporous silicon surfaces

Abstract The surfaces of a number of samples of macroporous silicon were characterized by electroreflectance spectroscopy. Specimens with pore diameters of 1–15 μm and pore depths from 15 to 80 μm were prepared by electrochemical etching with different values of current and bias. Etching enriches n-type silicon with majority carriers, and the existence of an intrinsic electric field is demonstrated. The intrinsic field develops due to the growth of an oxide layer on the pore walls. Correlation between the etching current and physical characteristics such as the phenomenological broadening parameter Γ, the magnitude of the intrinsic electric field, and the electro-optic energy is shown.