Optical studies of strain effects in quantum wells grown on (311) and (100) GaAs substrates - art. no. 195325

Pseudomorphic InGaAs/GaAs quantum wells (QW's) grown on vicinal substrates show a blueshift of the photoluminescence (PQ emissions with respect to (10 0) (nominal) ones. This effect has been discussed in the literature and it is associated with an inhomogeneous distribution of stresses in narrow quan tum wells. In order to study the shift of the PL emissions at large substra te misorientation angles, we have made PL measurements on three InGaAs/GaAs QW's (30 Angstrom wide), grown on (311)A, (311)B, and (100) substrates. We have done theoretical calculations considering the effect of strain on the conduction and valence bands of the QW's, where a single fitting parameter accounts for the inhomogeneous distribution of strain. Our model agrees wi th previously obtained results and reproduces the experimental PL blueshift s observed for the studied samples, showing that in relatively wider quantu m wells the inhomogeneous distribution of strain and indium segregation pla y a less important role than in narrow ones. In (100) and (311)A GaAs/AlGaA s samples subjected to an external hydrostatic pressure, our model shows, f or both samples, that the blueshift of the QW PL emissions increases with p ressure, in good agreement with experimental results, emphasizing the stron g relation between strain and blueshift regardless of the growth direction.