GROWTH OF INGAAS/GAAS HETEROSTRUCTURES WITH ABRUPT INTERFACES ON THE MONOLAYER SCALE

Segregation processes entail severe deviations from the nominal composition profiles of heterostructures grown by molecular beam epitaxy for most semiconductor systems. It is, however, possible to compensate exactly these effects, as shown here for InGaAs/GaAs. The deposition of a one-monolayer-thick indium-rich prelayer of InGaAs (or of a sub-monolayer amount of InAs) prior to growth of InxGa1-xAs allows forming a perfectly abrupt InxGa1-xAs-on-GaAs interface. Thermal annealing can furthermore be performed at the GaAs-on-InGaAs interface, so as to desorb surface indium atoms and suppress In incorporation in the GaAs overlayer. This powerful approach has been validated from a detailed study of the surface composition at various stages of the growth of InGaAs/GaAs quantum wells, as well as from high-resolution transmission electron microscopy and photoluminescence investigations.