Carrier diffusion in Cd1-xMnxTe

Carrier diffusion and electron-hole recombination are shown to be considerably slowed down in Cd1-xMnxTe semimagnetic semiconductors due to the efficient trapping of electrons on manganese sites. The theoretical interpretation is based on population dynamics, charge continuity equations, and Poisson's law. A simple analytical solution of this complicated system of equations is in very good agreement with the numerical one for a large range of durations of tie write pulses (from 100 ps to 1 mu s). Both calculations predict a reduction of electron mobility by a factor of 6000. These theoretical predictions are confirmed by the results of an experimental study performed by using the simple grating technique: We observe the temporal evolution of the diffracted signal when a continuous read beam is used to read gratings of different wavelengths encoded in the material by interfering write laser pulses. An effective ambipolar mobility of 0.54 cm(2)/V s is measured, which provides a value of 3400 cm(2)/V s for the intrinsic mobility in Cd0.7Mn0.3Te. This low ambipolar mobility could make this efficient material potentially interesting for parallel optical processing in the microsecond range. [S0163-1829(98)03436-5].