Synthesis of graphene-like passivating carbon layer into nanostructured porous silicon

The paper presents experimental results on the synthesis of graphene-like (Gr) films in gradient porous silicon structures with variable morphology (GPSi-var). Porous GPSi-var layers are characterized by the presence of a nanostructured layer (later nanoporous) on its surface. By increasing the depth of the anodic etching, the nanopores gradually transform into spongy and then into the columnar structure with micron-sized pores. The peculiarities of Gr layers’ synthesis in the walls of the pores throughout the depth of GPSi-var structures are studied. The proposed method of Gr film synthesis in the porous structure allows to form the carbon coating not only on the wall of the through pores in membrane, but also on the inner surface of the closed pores in the GPSi-var layers. It has been established that the composite formation of nanoporous silicon with Gr coating (GPSi-var/Gr) decreases the surface resistance of porous silicon layers by several orders of magnitude. The relatively higher stability of nanoporous composite layers to the impact of aqueous media has been experimentally demonstrated. Besides, it was found that the synthesized Gr layers are formed predominantly on the outer surface of the porous layer and crystal structure of its skeleton.