Electric isolation of porous silicon by electro generated polyethyleneimine film, comparison to thermal oxide

Electrochemical oxidation of diethylenetriamine (DETA) charged with 0.1 M LiSO3CF3, leads to a polymeric coating (polyethyleneimine film: PEI) on the porous silicon (PS) surface. The obtained passivated electrode is characterized through IRTF spectrometry and through C(V) curves on PS/PEI structures showing good insulating properties of the PEI film. The passivated electrode presents a linear pH sensitivity close to 62 mV per pH unit. Such sensitivity is higher compared to flat PEI passivated silicon electrode. The results were fitted with the generalized site-binding theory and the following parameters were found: the surface site density Ns was found to be equal to 3.6 × 1016 cm− 2 and pKH (KH acido-basic constant of the amino group) is − 5.54.