Ultrafast carrier trapping and slow recombination in ion-bombarded silicon on sapphire measured via THz spectroscopy

Abstract
We have performed two different types of femtosecond pump and probe measurements on THz transmitting antennas fabricated on ion-bombarded silicon-on-sapphire chips. We find evidence that the decay of the photoexcited current occurs on a time scale of less than 1 ps. Simultaneously, we observe unambiguous evidence of screening originating from carriers trapped in long-lived trap states. A simple model of carrier transport and screening in the presence of fast trapping and slow recombination is discussed.