Mechanism of Electron Injection During the Anodic Oxidation of Silicon

ABSTRACTn-Si photoanodes have been found to exhibit photocurrent multiplication during the first seconds of exposure to a fluoride-free, acidic electrolyte. This shows that, in contrast with earlier hypotheses, photocurrent doubling is not directly related to the presence of fluoride in the electrolyte, but rather must arise from an electron injection mechanism associated with the Si-H bonds initially present at the Si surface. It also suggests that the electroluminescence which has been observed during the anodic oxidation of porous silicon most probably stems from the same electron-injection mechanism.