ULTRAFAST CARRIER DYNAMICS AT A METAL-SEMICONDUCTOR INTERFACE

The ultrafast carrier dynamics in the high electric field at an Au-GaA s interface has been studied experimentally as well as theoretically. The photoluminescence decay time is related directly to the carrier sw eepout from the GaAs depletion region, i.e., to the time needed for ph otoexcited electrons and holes to leave this region. This decay time h as been found to increase drastically with laser input power, ranging from a few picoseconds at low excitation to values of 10-20 ps at high excitation. These results indicate a significant retardation of the s weepout, which cannot be explained by intervalley scattering and space -charge effects. From our Monte Carlo calculations it has been found t hat the applied electric held collapses totally almost instantaneously after laser excitation due to the enormous excess of photoexcited cha rges. The sweepout only recovers after some time needed to recharge th e device. (C) 1996 American Institute of Physics.