X-ray interference effect as a tool for the structural investigation of GaInAs/InP multiple quantum wells

Abstract

We present x-ray diffraction (XRD) investigations of the structure of nominally lattice-matched GaInAs/InP multiple quantum well (MQW) structures grown by chemical beam epitaxy (CBE). To obtain information about the individual MQW layers and the interface structure we make use of the x-ray interference effect between two layers of equal lattice constant but different layer thickness separated by ultrathin strained (interfacial) layers. This effect predicted by the dynamical diffraction theory provides a powerful tool to quantitatively investigate ultrathin single quantum well structures and monolayer thin interfaces as well as MQW structures. For a given switching sequence during CBE growth, we determine the interface structure of GaInAs/InP MQW structures within the limits given by XRD theory. Additionally we found that an As gradient from the GaInAs quantum well layers into the InP barrier layers is present. The influence of the substrate off-orientation, the growth 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 results 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.

Chopped InGaAs/InP quantum wells for a polarization-independent space switch at 1.53 μm

“…These chopped quantum wells show a QCSE red shift as large as 90 nm at 130 kV cm −1 , which is 30 times larger than in a 35 Å In 0.53 Ga 0.47 As QW. The CQW structure, including the interface layers [2,3] which are introduced during growth, is given in Table 1.…”

X-ray diffraction determination of the interface structure of CdSe/BeTe superlattices

“…X-ray diffractometry (XRD) is widely used for characterization of epitaxial layers and superlattices (SL) consisting of thin quantum wells (QWs) separated by barriers. Heterostructures on the basis of III-V (AlAs/GaAs, InAs/GaAs, InGaAs/InP etc) [1][2][3][4][5] and II-VI (ZnSe/ZnMgSe, CdSe/ZnSe) [6,7] compounds, as well as recently of III-nitrides [8][9][10] are among the objects investigated by high resolution XRD. XRD studies permit one to obtain such parameters of SLs as thickness, composition and strain of individual sublayers.…”

“…Most studies usually deal with the structures in which the thickness of QWs exceeds 20-30 Å. However, even in this case it is necessary to use independent technological data [1,4] or additional investigation methods like transmission electron microscopy (TEM), photoluminescence spectroscopy etc [1,2,5] in order to determine four or more parameters. The problem becomes more complicated if the QWs have monolayer (ML)-scale thicknesses.…”