Effect of wire width on strain distribution and bandgap in laterally aligned InGaAs/GaAs quantum wire nanostructures

The effect of InGaAs quantum wire width in the GaAs matrix on the strain distribution was studied using the finite element method and the resultant strain-modified bandgap was analysed in light of the 'model solid' theory of Van de Walle. The absolute magnitude of the strain in the bulk of the wire was attenuated significantly at the wire end along the width direction. Based on wire centres, the strain-modified direct bandgap increased with the decrease in wire width. The experimentally observed blueshift in photoluminescence spectra reported elsewhere was much higher than the predicted value based on the change in strain-modified bandgap especially at small-width wires. Other sources, such as the association of strain-relieved wire edge to the active region in the small-width wires, were interpreted to contribute significantly to the experimental blueshift.