Stacking of metamorphic InAlAs/InGaAs heterostructures on GaAs substrate

In this work, two lattice mismatched heterostructures called stacked metamo rphic high-electron mobility transistors have been grown showing the feasib ility of the metamorphic concept for the vertical integration of structures having different lattice parameters. Molecular-beam epitaxy of linear grad ed 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 s tep 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. (C) 2001 American Institute of Physics.