Electrochemical Impedance Study on n-type Si(100) in Hydrofluoric Acid

摘要

The photo-electrochemical behavior of n-type Si (100) in an ethanolic hydrofluoric acid (HF) has been investigated in this work. Dc-potentiodynamic polarization of the silicon, whose backside was lighted with a halogen lamp, was conducted in the HF solution containing ethanol or not. The voltammogram demonstrated that the anodic dissolution rate of the silicon in the HF solution was accelerated by illumination. Addition of ethanol into the HF solution resulted in electro-polishing inside the pits. Potentiostatic dissolution of the silicon, lighted with a halogen lamp (50 W), was conducted in 2 M HF solution containing various amounts of ethanol at potentials selected from the anodic polarization diagram. Electrochemical impedance spectroscopy was also carried out in the same condition. The surface morphology on the etched silicon under various conditions was examined by scanning electron microscopy (SEM).