Selective-Area Epitaxy of InGaAsP Buffer Multilayer for In-Plane InAs Nanowire Integration

In order to use III-V compound semiconductors as active channel materials in advanced electronic and quantum devices, it is important to achieve a good epitaxial growth on silicon substrates. As a first step toward this, we report on the selective-area growth of GaP/InGaP/InP/InAsP buffer layer nanotemplates on GaP substrates which are closely lattice-matched to silicon, suitable for the integration of in-plane InAs nanowires. Scanning electron microscopy reveals a perfect surface selectivity and uniform layer growth inside 150 and 200 nm large SiO₂ mask openings. Compositional and structural characterization of the optimized structure performed by transmission electron microscopy shows the evolution of the major facet planes and allows a strain distribution analysis. Chemically uniform layers with well-defined heterointerfaces are obtained, and the topmost InAs layer is free from any dislocation. Our study demonstrates that a growth sequence of thin layers with progressively increasing lattice parameters is effective to efficiently relax the strain and eventually obtain high quality in-plane InAs nanowires on large lattice-mismatched substrates.