In this study the control of interfacial layers in nanometre thin Ga x In 1−x As/InP heterostructures is demonstrated by variation of the growth interruption sequence (GIS) at the binary-ternary interfaces. All samples have been prepared by chemical beam epitaxy simultaneously growing the structures on exact (100) substrates and (100) substrates misoriented by 2 • towards (110). Characterization was by means of photoluminescence (PL) spectroscopy and high-resolution x-ray diffraction. It is shown that both composition and thickness of the interfacial layers can be manipulated on the (sub)monolayer scale with GIS times of the order of seconds. According to analysis of the x-ray data, interfaces can be tuned from +4 × 10 −3 compression to −4 × 10 −3 tension around nominally lattice-matched Ga x In 1−x As quantum wells of six monolayers thick. The PL investigations show that the tensile Ga x In 1−x P interfaces have no effect on the position of the PL peak maximum whereas compressive, InAs-like interfaces shift the transition to lower energy. This trend can be qualitatively understood but for all samples the calculated transition energies are higher than the measured values. Recommendations are given for further work which is not only of importance to the InP/Ga x In 1−x As system but should be applicable to quantum well structures in other materials where heterojunctions involve changes in both the group V and group III sublattices.

We have studied experimentally the edge channels in an externally controlled inhomogeneous twodimensional electron gas ͑2DEG͒ under quantum Hall conditions. The 2DEG is inhomogeneous in the sense that the electron concentration changes linearly across the width of the sample. In an impurity-free ͑or ideal͒ electron gas, these edge channels are wide compressible strips alternated with incompressible strips. However, when the presence of charged impurities ͑or disorder͒ is considered, localized compressible strips appear on both sides of the incompressible strips. We show that the width of the incompressible plus the localized compressible strips can be determined from resistance measurements. We further demonstrate that the macroscopically wide compressible strips in an inhomogeneous, disordered 2DEG act as if they are edge channels; they can be reflected at an interior potential and the values of the quantized resistances can be determined from the Landauer-Büttiker model. ͓S0163-1829͑96͒03028-7͔