Injection dependent carrier density imaging measurements including correction for trapping effects
Injection dependent lifetime measurements are often severely affected by trapping effects, resulting in an anomalous increase of lifetime under low-injection conditions. Carrier Density Imaging (CDI) measurements are presented where trapping effects are clearly present. Two different correction methods are proposed, based on the modeling of the injection dependent data. A model for CDI measurements, based on the Hornbeck-Haynes model is proposed as well as a bias-light correction adapted to CDI. Finally, a modification of the CDI setup is presented which allows to suppress trapping effects very efficiently. It is based on an additional irradiation with sub-bandgap light which is assumed to deplete trap levels resulting in trap-free lifetime measurements. A comparison of the carrier lifetimes resulting from these methods shows excellent correlation.