High Mobility Free-Standing InSb Nanoflags Grown On InP Nanowire Stems For Quantum Devices

TL;DR

This paper reports the optimized growth of defect-free, large-area free-standing 2D InSb nanoflags on nanowire stems, achieving record-high electron mobility suitable for quantum device applications.

Contribution

It introduces a method to grow high-quality, large 2D InSb nanoflags on nanowire stems with optimized morphology and orientation, enabling advanced quantum device fabrication.

Findings

Achieved electron mobility of ~29,500 cm2/Vs, the highest for free-standing 2D InSb structures.

Demonstrated defect-free zinc blend crystal structure and relaxed lattice parameters.

Successfully fabricated Hall-bar contacts for electrical characterization.

Abstract

High quality heteroepitaxial two-dimensional (2D) InSb layers are very difficult to realize owing to the large lattice mismatch with other widespread semiconductor substrates. A way around this problem is to grow free-standing 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 ~29,500 cm2/Vs is measured, which is the highest value reported for free-standing 2D InSb nanostrutures in literature. We envision the use of 2D InSb NFs for fabrication of advanced quantum devices.