Measurements of strain and bandgap of coherently epitaxially grown wurtzite InAsP-InP core-shell nanowires

TL;DR

This study experimentally measures the strain and bandgap of epitaxially grown wurtzite InAsP-InP core-shell nanowires, revealing their coherent strain states and potential for optoelectronic applications.

Contribution

It provides the first detailed experimental analysis of strain and bandgap in coherently strained wurtzite InAsP-InP nanowires using multiple characterization techniques.

Findings

Nanowires are of wurtzite phase and coherently strained.

Uniaxial strains are characterized and described analytically.

Bandgap energies are extracted from micro-photoluminescence measurements.

Abstract

We report on experimental determination of the strain and bandgap of InAsP in epitaxially grown InAsP-InP core-shell nanowires. The core-shell nanowires are grown via metal-organic vapor phase epitaxy. The as-grown nanowires are characterized by transmission electron microscopy, X-ray diffraction, micro-photoluminescence ($\mu$PL) spectroscopy and micro-Raman ($\mu$-Raman) spectroscopy measurements. We observe that the core-shell nanowires are of wurtzite (WZ) crystal phase and are coherently strained, with the core and the shell having the same number of atomic planes in each nanowire. We determine the predominantly uniaxial strains formed in the core-shell nanowires along the nanowire growth axis and demonstrate that the strains can be described using an analytical expression. The bandgap energies in the strained WZ InAsP core materials are extracted from the $\mu$PL measurements of individual core-shell nanowires. The coherently strained core-shell nanowires demonstrated in this work offer the potentials for use in constructing novel optoelectronic devices and for development of piezoelectric photovoltaic devices.