Hydrogenation-Driven Bandgap Engineering in InN Nanowires for Quantum Technologies and Optoelectronic Devices

InN is a promising III-nitride material due to its narrow bandgap and high carrier mobility, making it a suitable candidate for optoelectronic devices. The controlled modulation of its electronic and optical properties at the nanoscale can become central to the development of future quantum photonic devices. In this work, we envision a novel methodology for engineering quantum dots (QDs) within individual InN nanowires (NWs) via low-energy hydrogen ion irradiation. Our approach leverages spatially selective hydrogenation to locally modify the band structure of InN NWs, enabling the formation of potential wells—thus creating QD-like confinement regions without the need for conventional heterostructure growth. To investigate and optimize this bandgap engineering strategy, in this work pristine Mg-doped InN NWs grown on Si are subjected to varying hydrogenation doses and process temperature, inducing a change in the bandgap energy as big as 0.5 eV, similar to epilayers [1]. Micro-photoluminescence (μ-PL) measurements on single NWs, also as a function of power and temperature, are employed to directly probe the bandgap changes and investigate emission features. Post-hydrogenation annealing (thermal and laser) is introduced as an additional control parameter to fine-tune the defect landscape and further refine the bandgap profiles. Annealing not only improves the optical quality by removing hydrogen from the wires but also enables reversibility of the hydrogen-induced bandgap modifications. The combined use of hydrogenation and thermal treatment provides a powerful dual-knob approach to achieve precise, localized control over the band structure. This reversible control over the bandgap adds an extra degree of flexibility to our post-growth tuning approach. Besides their potential as quantum light sources, the ability to span a broad spectral range positions InN nanowires as strong candidates for advanced optoelectronic and solar energy applications, similarly to the typical InGaN heterostructures.