Stacking of metamorphic InAlAs/InGaAs heterostructures on GaAs substrate

Abstract

In this work, two lattice mismatched heterostructures called stacked metamorphic high-electron mobility transistors have been grown showing the feasibility of the metamorphic concept for the vertical integration of structures having different lattice parameters. Molecular-beam epitaxy of linear graded buffer layers allows the relaxation of the mismatch strain by generation of misfit dislocations. X-ray reciprocal space mapping and cross sectional transmission electron microscopy confirm the interest of growing inverse step buffer layers to achieve high relaxation rates with good confinement of misfit dislocations. The quality of these stacked structures was confirmed by photoluminescence, Hall effect measurements, and the dc characteristics of the transistors.