Quantum real-space transfer in a heterostructure overgrown on the cleaved edge of a superlattice

Abstract

A dispersion relation for an electron in a two-layer (and also multilayer) quantum well (QW) is formed as a result of a certain combination of initial dispersion relations for each of the forming layers. Such a combination can be used to engineer new dispersion relations with desirable properties. The same relates to a two-dimensional electron gas (2DEG) induced in a multilayer medium. In this study, we consider first such a 2DEG in a specific two-layer structure where a superlattice (SL) plays the role of the second half-infinite layer, and electrons with large wave numbers along the SL vector spread from the first ordinary QW layer to this SL. As a result of such a quantum (dynamic) real-space transfer, electrons become heavier, and the dispersion relation achieves an additional negative effective mass (NEM) section. Such NEM dispersion relations were studied for several different material systems, including the two most interesting three-material systems: (1) an isomorphic Al0.15Ga0.85As//GaAs/Al0.5Ga0.5AsAl0.15Ga0.85As//GaAs/Al0.5Ga0.5As structure and (2) a strained In0.53Ga0.47As//InxGa1−xAs/InyAl1−yIn0.53Ga0.47As//InxGa1−xAs/InyAl1−y As structure (x>0.53,(x>0.53, y<0.52)y<0.52) with a strain-balanced InxGa1−xAs/InyAl1−yAsInxGa1−xAs/InyAl1−yAs SL. Most of the results were verified using a simplified 1D model, but some of them were verified by more complicated 2D-model calculations. © 2003 American Institute of Physics.