We have used an electrical technique to determine the ambipolar lifetime inphyphen;ihyphen;nGaAs/AlGaAs selfhyphen;electrohyphen;optichyphen;effect devices in which theiregion consists of a multiple quantum well structure (MQW). From an analysis of the voltage drop in theiregion obtained from the forward currenthyphen;voltage characteristics, values for the ambipolar lifetimes are derived for diodes with different MQW. A value of 80ndash;90 ps is determined for the ambipolar lifetime which is found not to change significantly when the AlxGa1minus;xAs barrier thickness or composition is reduced from 65 to 35 Aring; orxsim;0.3 to 0.2, respectively, in the MQW. Since these changes in the barrier have previously been shown to improve photoresponse efficiency of thephyphen;ihyphen;ndiode, it is inferred that the carrier escape and collection times are smaller than 80ndash;90 ps in devices with thin (35 Aring;) or low (xsim;0.2) AlxGa1minus;xAs barrier.
展开▼
