Bandgap Engineering On Demand in GaAsN Nanowires by Post-Growth HydrogennImplantation

TL;DR

This study demonstrates reversible, tunable, and non-destructive post-growth bandgap engineering in GaAsN nanowires using hydrogen implantation and annealing, enabling precise control of optical properties for photonic devices.

Contribution

It introduces a novel method of post-growth bandgap tuning in GaAsN nanowires via hydrogen implantation, which was previously unattainable in epilayers.

Findings

Bandgap increased by up to 460 meV through hydrogen implantation.

Photoluminescence efficiency increased by an order of magnitude.

Bandgap tuning is reversible and can be locally controlled by laser annealing.

Abstract

Bandgap engineering in semiconductors is required for the development of photonic and optoelectronic devices with optimized absorption and emission energies. This is usually achieved by changing the chemical or structural composition during growth or by dynamically applying strain. Here, the bandgap in GaAsN nanowires grown on Si is increased post-growth by up to 460 meV in a reversible, tunable, and non-destructive manner through H implantation. Such a bandgap tunability is unattained in epilayers and enabled by relaxed strain requirements in nanowire heterostructures, which enables N concentrations of up to 4.2% in core-shell GaAs/GaAsN/GaAs nanowires resulting in a GaAsN bandgap as low as 0.97 eV. Using micro-photoluminescence measurements on individual nanowires, it is shown that the high bandgap energy of GaAs at 1.42 eV is restored by hydrogenation through formation of N-H complexes. By carefully optimizing the hydrogenation conditions, the photoluminescence efficiency increases by an order of magnitude. Moreover, by controlled thermal annealing, the large shift of the bandgap is not only made reversible, but also continuously tuned by breaking up N-H complexes in the hydrogenated GaAsN. Finally, local bandgap tuning by laser annealing is demonstrated, opening up new possibilities for developing novel, locally and energy-controlled quantum structures in GaAsN nanowires.