Abstract
Oscillatory relaxation of surface photovoltage has been observed by time-resolved photoemission spectroscopy on a Si(111)7 × 7 surface with a temporal period of several tens of nanoseconds. The oscillation was reproduced by solving non-linear Master equations that describe surface recombination of electron-hole pairs associated with the formation of exciton-like states at the surface. Appearance of non-linear phenomena is naturally expected by the model when high density photo-excited carriers are generated by the high power laser pulse. © 2014 Elsevier B.V.