Exploiting of flux shadowing effect on In$_{x}$Ga$_{1-x}$As asymmetric shell growth for strain and bending engineering in GaAs - In$_{x}$Ga$_{1-x}$As core - shell NW arrays

TL;DR

This paper investigates non-uniform shell growth on GaAs nanowires using molecular beam epitaxy, demonstrating how flux shadowing influences strain and bending profiles, enabling strain engineering in NW arrays.

Contribution

It introduces a method to control strain and bending in GaAs-InGaAs core-shell nanowires through flux shadowing effects during MBE growth, enabling tailored strain distributions.

Findings

Bending profiles depend on substrate pitch size.

Strain distribution can be precisely controlled.

Segment lengths of bent and straight NWs are tunable.

Abstract

Here we report on non-uniform shell growth of In(x)Ga(1-x)As onto GaAs nanowire (NW) core by molecular beam epitaxy (MBE). The growth was realized on pre-patterned silicon substrates with pitch size (p) ranging from 0.1 um to 10 um. Considering the preferable bending direction with respect to the MBE cells as well as the layout of the substrate pattern, we are able to modify the strain distribution along the NW growth axis and the subsequent bending profile. For NW arrays with high number density, the obtained bending profile of the NWs is composed of straight (barely-strained) and bent (strained) segments with different lengths which depend on the pitch size. A precise control of the bent and straight NW segment length provides a recipe to design NW based devices with length selective strain distribution.