X-RAY INTERFERENCE EFFECT AS A TOOL FOR THE STRUCTURAL INVESTIGATION OF GAINAS INP MULTIPLE-QUANTUM WELLS/

We present x-ray diffraction (XRD) investigations of the structure of nominally lattice-matched GaInAs/InP multiple quantum well (MQW) struc tures grown by chemical beam epitaxy (CBE). To obtain information abou t the individual MQW layers and the interface structure we make use of the x-ray interference effect between two layers of equal lattice con stant but different layer thickness separated by ultrathin strained (i nterfacial) layers. This effect predicted by the dynamical diffraction theory provides a powerful tool to quantitatively investigate ultrath in single quantum well structures and monolayer thin interfaces as wel l as MQW structures. For a given switching sequence during CBE growth, we determine the interface structure of GaInAs/InP MQW structures wit hin the limits given by XRD theory. Additionally we found that an As g radient from the GaInAs quantum well layers into the InP barrier layer s is present. The influence of the substrate off-orientation, the grow th rate, and the group V flux in the InP barriers on the total amount of strain incorporated into the InP layers is shown. The obtained resu lts indicate that the mechanism of As incorporation into InP layers is similar to the mechanism observed for the As incorporation into (qua) ternary GaxIn1-xAsyP1-y layers. (C) 1998 American Institute of Physics . [S0021-8979(98)02307-X].