Simultaneous measurements of transient photo-current andphotoluminescence for (Al_0.7Ga_0.3)_0.5In_0.5P/Al_xIn_1-xP-superlattices

摘要

The photoluminescence and the photo-current are simultaneouslymeasured for indirect transition type undoped(Al_0.7Ga_0.3)_0.5In_0.5P/Al_xIn_1-xP (x=0.53 and 0.57) superlattices. Biasvoltage is applied to the semi-transparent Au electrode on the epitaxiallayer. From measurements of the sample with x=0.53 (lattice matched tothe GaAs substrate) under a bias voltage of +0.3 V, it is found that thecarrier transport affects the PL decay curve only slightly. The latteris dominated by radiative carrier recombination. The surface electricfield of the sample without electrodes is estimated to be less than3×103 V/cm. For the sample with x=0.57, the energystates originating from the crystal defects act as carrier traps under alow electric field, and levels which contribute to the tunneling ofelectrons through the barriers under a high electric field