A high-speed photocurrent multiplication device based on an organic double-layered structure

A high-speed photocurrent multiplication device that has an organic double- layered structure was fabricated. In this device, the improvement in the un iformity of the organic films, caused by inserting an additional amorphous- like organic underlayer, enabled high-electric-field operation of the devic e. Owing to efficient carrier photogeneration under the application of high er voltages, the response time of the multiplied photocurrent became shorte r without a decrease in the multiplication rate, and showed clear saturatio n above 18 V. At a high applied voltage of 20 V, a large multiplication rat e of 1.7 x 10(5)-fold, with a high-speed response of 3.7 s, was achieved. A rise time of only 26 ms required for the 1000-fold multiplication suggests that the multiplication device could potentially be applied to a practical imaging device. (C) 2000 American Institute of Physics. [S0003-6951(00)009 09-8].