Scanning voltage microscopy on buried heterostructure multiquantum-well lasers: identification of a diode current leakage path

We report scanning voltage microscopy (SVM) results on actively driven buried heterostructure (BH) multiquantum-well (MQW) lasers that exhibit current blocking failure at high current injection operation. The measured two-dimensional image of local voltage distribution delineates the buried structures of the BH laser. The results, in combination with light-current-voltage (L-I-V) measurements, connect macroscopic external performance to measurements on the nanometer scale. Our experimental results suggest that the current blocking breakdown observed in the MQW BH lasers correlates with the turn-on of a diode leakage path when the devices are biased at high current injection.