Simultaneous measurements of transient photo-current and photoluminescence for (Al/sub 0.7/Ga/sub 0.3/)/sub 0.5/In/sub 0.5/P/Al/sub x/In/sub 1-x/P-superlattices

The photoluminescence and the photo-current are simultaneously measured for indirect transition type undoped (Al/sub 0.7/Ga/sub 0.3/)/sub 0.5/In/sub 0.5/P/Al/sub x/In/sub 1-x/P (x=0.53 and 0.57) superlattices. Bias voltage is applied to the semi-transparent Au electrode on the epitaxial layer. From measurements of the sample with x=0.53 (lattice matched to the GaAs substrate) under a bias voltage of +0.3 V, it is found that the carrier transport affects the PL decay curve only slightly. The latter is dominated by radiative carrier recombination. The surface electric field of the sample without electrodes is estimated to be less than 3/spl times/10/sup 3/ V/cm. For the sample with x=0.57, the energy states originating from the crystal defects act as carrier traps under a low electric field, and levels which contribute to the tunneling of electrons through the barriers under a high electric field.