Improved compositional abruptness at the InGaAs on GaAs interface by presaturation with In during molecular-beam epitaxy

Abstract

Surface segregation of In atoms during molecular beam epitaxy of InGaAs layers greatly influences the composition profile in the vicinity of both the normal and the inverted Ga(Al)As/InGaAs interface, inherently limiting compositional abruptness. We find, for example, that the intended alloy composition in In0.22Ga0.78As is not reached until nearly 35 Å from the InGaAs on GaAs interface for growth at 500 °C. We propose and demonstrate how the compositionally graded region in InGaAs can be eliminated by preadsorbing a fixed amount of In onto the GaAs surface to match the surface segregated layer during steady state, before depositing the InGaAs layer.