Transient Measurements of Ultrafast Charge Collection in Semicouductor Diodes

Funneling-current transients produced in semiconductor devices are predicted to occur on a picosecond time scale. We have measured these transients using a high bandwidth sampling system. Measurements were made on 1, 3, and 10 ¿-cm silicon low capacitance diodes and 1016 cm-3 Te-doped GaAs diodes. The data is compared to the Hsieh, Murley and O´Brien, the McLean and Oldham, and the Messenger models. Risetime versus doping density, peak current, total charge, and amplitude versus bias were measured. Also, current transients and prompt charge versus energy are presented.