Dependence of properties of variable gradient porous structure of silicon on the method of formation

A series of samples of gradient-porous silicon structures with crystallographic orientations (100) and (111) by deep anode etching was obtained. Dependences of the rate of deep anodic etching and the depth of the porous layer of the samples on the anode current density are shown. The absorption and reflection coefficients of the samples were investigated by optical spectrometry depending on their crystallographic orientation and the depth of the porous layer. The influence of water solutions on the optical properties of the samples was determined.