InAs monolayers and quantum dots in a crystalline GaAs matrix

Abstract

The authors have developed a new approach to fabricate coherent InAs insertion in a crystalline GaAs matrix by conventional MBE. The 7% lattice mismatch between InAs and GaAs requires specific strategies to individually control the formation of the InAs/GaAs and GaAs/InAs interfaces, which is governed by a unique balance of surface and interface energy as well as kinetic processes. The interfaces of the strained InAs insertions are then in register with the surrounding GaAs matrix, as determined by high-resolution X-ray diffraction and transmission electron microscopy. This high level of growth control allows one to fabricate a novel class of artificial materials by using either exactly (001)-oriented substrates or vicinal substrates tilted towards (100). The controlled incorporation of fractions of InAs monolayers into the GaAs matrix offers the unique possibility of manipulating the translational motion of excitons in the crystal on an atomic scale and hence to tune the optical response. Moreover, the authors are able to obtain isolated InAs quantum dots in a crystalline GaAs matrix on vicinal (001) GaAs substrates. The absence of any surface and interface states makes this system promising for the study of the optical response of ultrasmall zero-dimensional systems.