Carrier mobility in an ethylene vinyl acetate (EVA) copolymer film was meas
ured by a new technique. The time-dependent charge distribution was monitor
ed by the pulsed-electroacoustic method when a pulse voltage was superposed
on a dc bias voltage. A positive charge packet was injected from the anode
soon after the pulse application, and moved towards the cathode. It was su
ggested from the movement of the charge packet that the mobility of the pos
itive carrier at 10 to 60 MV/m was in the order of 10(-13) m(2)/Vs at room
temperature. When the pulse voltage was very high, a charge packet appeared
within the bulk, suggesting that carrier dissociation takes place.