Investigation of the Local Chemical States in the Structures of Macroporous Silicon

The chemical states and the surface structure of macropores in silicon were investigated in relation to the conditions of electrochemical treatment. The microporous layers on the walls of the macropores like flat microporous layers contain oxides and organic compounds. The structures of macroporous silicon, prepared at potentials higher than the first peak of the voltammetric characteristics, contain additional hydride peaks.     

Investigation of electrochemical macropore formation in silicon

We have studied electrochemical pore formation conditions in macroporous silicon structures as the applied voltage is varied linearly. Within the framework of the diffusion-drift model, we have determined the relationship between the parameters of the electrochemical process (illumination intensity, current density, applied voltage). The experimental curves for macropore formation conditions correspond to the diffusion-drift model for transport of nonequilibrium holes when the anode thickness is greater than the hole diffusion length and the macropore radii are relatively large. Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 45 Prospekt Nauki, Kiev 03028, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 3, pp. 193–197, May–June, 2000.     

Influence of Electrochemical Parameters on the Etching of Macropores in Silicon

The process of formation of macropores in silicon with stationary irradiation and a constant current density during the electrochemical process in dependence on the initial bias on the silicon anode, U ₀, has been studied. Stable formation of macropores began when the bias reached U _c, corresponding to a critical concentration of holes p _c at the silicon–electrolyte interface. The process of macropore formation is unstable with U ₀ > U _c.