The peculiarities of electron emission from electronic states of nanodefects formed at the early stages of oxygen precipitation in oxygen-implanted silicon annealed at 700°C were investigated with a combination of capacitance and current transient spectroscopy of the space charge region (SCR) in semiconductors. It was established that the particular properties of acceptor-like states are due to their high density and their localization at the back side of the implanted region. A model is suggested that explains an apparent emission rate slowdown and the appearance of an unexpected sign of capacitance relaxation signal as a result of the non-monotonic shape of the potential of the Schottky-diode.