Study of the Differential Capacitance of Space Charge at the Interface of the p-Silicon Paste Electrode /Carmin Indigo Electrolyte for Electrochemical Sensor Applications

This study is on the optimisation of the interface of the p-silicin/indigo camine for electrochemical sensors applications. In this study carried out in cyclic voltammetry, the p-type silicon paste electrode is in contact with the indigo carmine solution at pH=10. The nature of the current in the silicon / aqueous alkaline solution of indigo carmine junction was determined. The cyclic voltammogram is correlated by an affine straight-line, which allows the determination of the capacitance of the junction at a frequency of 50 Hz. Curve C-2=f(E) obtained is not linear. It is of Gaussian form. This form reflects that the ionization of the deep levels of the semiconductor began before the depopulation of the valence band. This study allows to determine the surface potential (Vs=-0,4V) and the flat band potential (VBP=-1,50V). The fermi potential is equal to 1, 50 These results are indications that this interface could not be used as an electrochemical sensor under these conditions.