High-Mobility Free-Standing InSb Nanoflags Grown on InP Nanowire Stems for Quantum Devices

High-quality heteroepitaxial two-dimensional (2D) InSb layers are very difficult to realize because of the large lattice mismatch with other widespread semiconductor substrates. A way around this problem is to grow freestanding 2D InSb nanostructures on nanowire (NW) stems, thanks to the capability of NWs to efficiently relax elastic strain along the sidewalls when lattice-mismatched semiconductor systems are integrated. In this work, we optimize the morphology of free-standing 2D InSb nanoflags (NFs). In particular, robust NW stems, optimized growth parameters, and the use of reflection high-energy electron diffraction (RHEED) to precisely orient the substrate for preferential growth are implemented to increase the lateral size of the 2D InSb NFs. Transmission electron microscopy (TEM) analysis of these NFs reveals defect-free zinc blend crystal structure, stoichiometric composition, and relaxed lattice parameters. The resulting NFs are large enough to fabricate Hall-bar contacts with suitable length-to-width ratio enabling precise electrical characterization. An electron mobility of similar to 29 500 cm(2) /(V s) is measured, which is the highest value reported for free-standing 2D InSb nanostructures in literature. We envision the use of 2D InSb NFs for fabrication of advanced quantum devices.

Automated summary

The study optimized the morphology of free-standing 2D InSb nanoflags (NFs), increasing their lateral size while maintaining defect-free zinc blend crystal structure, stoichiometric composition, and relaxed lattice parameters. These NFs were found large enough to fabricate Hall-bar contacts for precise electrical characterization, resulting in a measured electron mobility of approximately 29,500 cm(2) /(V s), the highest reported for free-standing 2D InSb nanostructures in literature. The study envisions the use of 2D InSb NFs for the fabrication of advanced quantum devices.