Picosecond and femtosecond laser pulses will be used to study ultrafast optical and electronic processes in semiconductors. Three projects will be supported by the PYI program. Nucleation processes and superheating of Si after illumination with a ps high power laser pulse will be studied by time-resolved spectroscopy techniques. Hot carrier relaxation in the extended states, carrier trapping across the mobility edge and thermalization in the bandtail states will be investigated by femtosecond spectroscopy in a-Si:H and related alloys. Picosecond electrical pulses will be produced using the Auston switch technology. The transient response of III-V semiconductor superlattices to these pulses will be investigated theoretically. Emphasis will be put on the variations of the optical properties.
