Time transient investigation of photo-induced electron localization at atomic step edges of Si (1Â 1Â 1)

To analyze a photo-induced electron localization process at atomic step edges of the Si-native oxide interface, the time transient signal of Kelvin force microscopy with a UV laser light source was investigated. The time constant of the photo-induced process for a laser wavelength λ = 325 nm had a linear dependence with respect to the laser power Pw. An electron transition model that takes into account photo- and thermal-effects revealed that the photo-induced localization is dominant for Pw > 0.54 mW. The small photo irradiation effect occurring at λ = 441.6 nm is explained by the low photo absorption efficiency for visible light.