The approximations of charge relationships at normally doped semiconductor interfaces were qualitatively derived basis on electrical neutrality conditions. Effects of ion adsorptions, activation processes, interfacial structures, rectifying phenomena, and effects of surface potential barriers at the p- and n-Si/CsNO3 aqueous electrolytes, and the p-Si/(1HF:3HNO3:6H2O) electrolyte solutions were investigated using a cyclic voltammetric method. The space charge acts the most important role for the pn junction structures, the rectifying phenomena, and the activation processes. The Current-Voltage (I-V) characteristics curves significantly depend on developing of the Helmholtz double layers and charging of the show surface states during the activation processes. A linear Current-Voltage characteristics region was observed at the p-Si/(1HF:3HNO3: 6H2O) electrolyte solution interface.