Transport of Photoexcited Carriers in Evaporated GexSe1-x Glass Films

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Abstract
Measurement of the time-of-flight of optically injected carriers was carried out in evaporated Ge x Se1-x (0.2\leqslantx\leqslant0.4) glass films. The charge signal induced by drifting electrons showed the existence of two components corresponding to fast and slow electrons. The fast component was due to the nondispersive drift of electrons with high mobility which has been observed similarly in thick bulk samples while the slow component showed a dispersive transport character. The effective drift mobility was estimated from the kink point of the log-log plot of the current versus time. The magnitude of the fast component of the induced charge signal tended to saturate at high electric fields. On the basis of a simple model, the mobility and the carrier lifetime were separately estimated. Holes showed only the dispersive transport and the value of the effective hole mobility was close to that of the slow electrons.