Measurement of AlGaAs/AlGaAs interface recombination velocities using time-resolved photoluminescence
Time-resolved photoluminescence has been used to examine AlxGa1?xAs/AlyGa1?yAs interfaces, focusing on the recombination velocity. For an Al0.08Ga0.92As/Al0.88Ga0.12As interface, important for solar cells, recombination velocities are about 104 cm/s with the growth conditions used in this study. Several types of interface passivation were attempted, but the most successful was the insertion of thin Al0.14Ga0.86As layers between the other two alloys. Using this technique, a 16-fold increase (to ~20 ns) of the minority-carrier lifetime was measured in a 0.8-µm-thick Al0.08Ga0.92As layer in which interface recombination would normally have limited the lifetime to about 1–2 ns. Compositional grading was found to be ineffective at passivating the interfaces. Applied Physics Letters is copyrighted by The American Institute of Physics.