ULTRAFAST PULSE GENERATION IN PHOTOCONDUCTIVE SWITCHES

Carrier and held dynamics in photoconductive switches are investigated by electrooptic sampling and voltage-dependent reflectivity measureme nts, We show that tile nonuniform field distribution due to the two-di mensional nature of coplanar photoconductive switches, in combination with the large difference in the mobilities of holes and electrons, de termine the pronounced polarity dependence, Our measurements indicate that the pulse generation mechanism is a rapid voltage breakdown acros s the photoconductive switch and not a local held breakdown.