MEDIATION OF STRAIN FROM IN0.36GA0.64AS LAYERS THROUGH GAAS BARRIERS IN MULTIPLE-QUANTUM-WELL STRUCTURES

The strain mediation in multiple quantum well structures consisting of In0.36Ga0.64As layers separated by GaAs barriers has been investigated by photoluminescence. Strain in layers grown by molecular beam epitaxy was evaluated by comparing the photoluminescence-peak energies with calculated recombination energies in strained quantum wells using the effective-mass Schrödinger equation. In structures consisting of two 40 Å thick In0.36Ga0.64As layers separated by a GaAs barrier, onset of relaxation is not observed until the barrier thickness is reduced below 100 Å. The corresponding value is 180 Å in a structure with two 50 Å thick In0.36Ga0.64As layers. Results also show that strain mediation increases with the number of strained In 0.36Ga0.64As layers. In multiple quantum well structures with four 50 Å thick In0.36Ga0.64As layers, the barrier thickness required to stop strain mediation increases to 225 Å. In similar structures with eight and twenty 50 Å thick In 0.36Ga0.64As layers this value is 275 Å. © 1994 American Institute of Physics.