TUNNELING-INDUCED OPTICAL NONLINEARITIES IN ASYMMETRIC AL0.3GA0.7AS/GAAS DOUBLE-QUANTUM-WELL STRUCTURES

A photoluminescence study of the optical response in asymmetric, double-quantum-well structures is presented. The results reveal the existence of strong nonlinearities that can be attributed to electron and hole tunneling through the barrier layer. These nonlinearities arise from the difference between the electron and heavy-hole effective masses. The band bending resulting from spatial charge separation has a strong influence on the measured photoluminescence intensities for peaks associated with transitions between the lowest-energy electron and hole subband states in each quantum well. The system is strongly perturbed by an anticrossing of the second- and third-order heavy-hole subbands. Establishment of the heavy-hole resonant tunneling condition is shown to influence the intensities of the quantum-well photoluminescence peaks strongly. An effective-mass model of the double-quantum-well system reveals how the strength of these effects depends on both interwell coupling and the degree of structural asymmetry. This model successfully predicts the heavy-hole anticrossing observed in photoluminescence. © 1990 The American Physical Society.