Residual electrolyte as a factor influencing the electrical properties of porous silicon

The electrical properties of luminescent porous silicon layers (PS) were studied using a method of a.c. impedance spectroscopy in a range of electric field frequencies 0.175-10(5) Hz (amplitude 1 V) and temperatures -100 degrees C to +200 degrees C. It was found that the a.c. electrical conductivity of PS is very sensitive to its post-anodizing treatments. An electric equivalent circuit was designed to fit the experimental data acquired at differently treated PS samples. The components of the equivalent circuit were assigned to physical elements of PS (a surface phase on top of PS and a layer of underlying bulk material). Different post-growth treatments (training by a.c. electric field and temperature, pore filling by inert electrolyte, evacuation at increased temperatures) result in changing the electrical properties of the PS samples. This allows the conclusions to be made about the existence of residuals of the electrolyte inside the pores of freshly prepared PS and their influence onto its aging stability.