Wet Chemical Etching of GaAs Nanowires for Quantum Confinement

The quantum confinement in III–V semiconductors displays important applications such as lasers or single-photon sources. III–V nanowires (NWs) are ideal candidates for the integration of direct bandgap material on silicon. However, to reach quantum confinement, small diameters are needed. In this work, we perform wet chemical etching of NWs to reduce their diameter. In contrast to plasma irradiation and high-temperature techniques, this approach is more energy-efficient and causes less physical damage. With accurate control of the etching rate in an acidic solution, we obtained NW diameters as small as 20 nm. A 60 nm-thick AlGaAs shell was regrown on the NWs after the etching, and STEM images showed a fully crystalline interface of the core and the shell. Finally, photoluminescence measurements reveal a blueshift of ∼20 meV due to reduced diameters. This study demonstrates the potential of a top-down approach via wet chemical etching to tune the III–V NW morphology.