# Revealing large-scale homogeneity and trace impurity sensitivity of GaAs nanoscale membranes

## TL;DR

This study investigates GaAs nanomembranes, revealing their large-scale uniformity and impurity sensitivity, which are crucial for advancing optoelectronic applications and energy harvesting technologies.

## Contribution

It demonstrates the optical quality of uncapped GaAs nanomembranes and their consistent emission properties across scales, highlighting their potential for large-scale use.

## Key findings

- Uncapped membranes show extremely narrow exciton emission.
- Capping with AlGaAs increases emission but introduces impurity-related broadening.
- Emission properties are consistent across different size scales.

## Abstract

III-V nanostructures have the potential to revolutionize optoelectronics and energy harvesting. For this to become a reality, critical issues such as reproducibility and sensitivity to defects should be resolved. By discussing the optical properties of MBE grown GaAs nanomembranes we highlight several features that bring them closer to large scale applications. Uncapped membranes exhibit a very high optical quality, expressed by extremely narrow neutral exciton emission, allowing the resolution of the more complex excitonic structure for the first time. Capping of the membranes with an AlGaAs shell results in a strong increase of emission intensity but also to a shift and broadening of the exciton peak. This is attributed to the existence of impurities in the shell, beyond MBE-grade quality, showing the high sensitivity of these structures to the presence of impurities. Finally, emission properties are identical at the sub-micron and sub-millimeter scale, demonstrating the potential of these structures for large scale applications.