Ultrafast Relaxation of Photocarriers in Cadmium Sulfide

Experiments are performed on registering induced changes in the refractive index of a cadmium sulfide single crystal with femtosecond time resolution in the transient lens and transient gratings geometries. The lifetime of photoexcited charge carriers (photocarriers) is estimated at 230 ps. An additional component, characterized by a decay time of units of picoseconds, is found in the efficiency decay of the transient grating of free carrier concentration. It is shown that this time is determined by the thermalization rate of photocarriers.