Tuning hole mobility of individual p-doped GaAs nanowires by uniaxial tensile stress

TL;DR

This study demonstrates how uniaxial tensile stress can modulate hole mobility in individual GaAs nanowires, revealing strain-induced electronic property changes with potential for device engineering.

Contribution

It provides direct experimental evidence linking uniaxial stress to hole mobility changes in GaAs nanowires using in situ TEM techniques, a novel approach in strain engineering.

Findings

Conductivity varies with applied stress, decreasing then increasing.

Lattice strain distribution is complex and spatially non-uniform.

Band gap shifts significantly under stress and strain.

Abstract

Strain engineering provides an effective way of tailoring the electronic and optoelectronic properties of semiconductor nanomaterials and nanodevices, giving rise to novel functionalities. Here, we present direct experimental evidence of strain-induced modifications of hole mobility in individual GaAs nanowires, using in situ transmission electron microscopy (TEM). The conductivity of the nanowires varied with applied uniaxial tensile stress, showing an initial decrease of ~5-20% up to a stress of 1~ 2 GPa, subsequently increasing up to the elastic limit of the nanowires. This is attributed to a hole mobility variation due to changes in the valence band structure caused by stress and strain. The corresponding lattice strain in the nanowires was quantified by in situ 4D-scanning TEM (STEM) and showed a complex spatial distribution at all stress levels. Meanwhile, a significant red shift of the band gap induced by the stress and strain was unveiled by monochromated electron energy loss spectroscopy.