Time-resolved electroabsorption measurement of the electron velocity-fieldcharacteristic in GaN

A femtosecond optically detected time-of-flight technique that monitors the change in the electroabsorption associated with the transport of photogene rated carriers in a GaN p-i-n diode has been used to determine the room-tem perature electron transit time and steady-state velocity as a function of e lectric field. The peak electron velocity of 1.9 x 10(7) cm/s, correspondin g to a transit time of 2.5 ps, is attained at 225 kV/cm. The shape of the v elocity-field characteristic is in qualitative agreement with theoretical p redictions. (C) 2000 American Institute of Physics. [S0003-6951(00)01009-3] .