ИСТИНА

Layers of porous silicon (PSi) and silicon nanowires (SiNWs) were formed on lightly and heavily Borondoped ptype (100) cSi wafers by using electrochemical etching, stain etching or metalassisted chemical one in hydrofluoric acid solutions. Theoretical analysis and experimental data showed that it was possible to select a profile of the effective refractive index of PSi layer with total thickness about 500 nm, which allowed us to achieve a very low reflection about 14% and transmittance up to 96% in the spectral range of 4001100 nm. SiNWs layers with thickness above 500 nm revealed the total reflectance below 1% that could be used for antireflection coating of solar cells. Numerical simulations predict an effect of free charge carriers with concentration above 10^18 cm^3 in the cores of SiNWs on both the reflection and absorption in the spectral range of wavelength longer than 1 μm. The obtained experimental data confirm the theory predictions and indicate that such kind of Sibased nanostructures can be useful to create modulators, optical switches and other photonic devices for the infrared spectral region.