Numerical analysis of electric field profiles in high-voltage GaAs photoconductive switches and comparison to experiment

The electric field in GaAs photoconductive switches has been observed with an ultrafast electro-optic imaging system to develop complex spatial and temporal structure immediately after illumination. High-field domains form at the switch cathode as the photogenerated carriers recombine for bias fields above approximately 10 kV/cm. At these biases, the switch also remained conductive for a much longer time ( approximately 100 ns) than the material recombination time ( approximately 1 ns). A model which includes field-dependent mobility was developed to explain this data. Simulation of the electric field profile across the switch indicates that high-field domains which form at the switch cathode are the result of negative differential resistance.<
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