Semiconductor nanowires offer unique opportunities for next-generation electronic and photonic devices due to their high surface-to-volume ratio, ability to suppress dislocations, accommodate large lattice mismatches, and support both axial and radial heterostructure growth. In particular, the non-polar planes of GaN nanowires provide a promising platform for high-performance optoelectronics by mitigating quantum-confined Stark effects and reducing Auger recombination losses.
STROBE scientists, together with collaborators in Cambridge, Lund, and Denmark, report the discovery of unexpected electrostatic potential wells across the non-polar m-plane and at the core/shell interface in n-type GaN nanowires. Using off-axis electron holography (OAEH), quantum-well-like potential drops were mapped at both the core/shell interface and the nanowire center. Valance electron energy loss spectroscopy (VEELS) revealed localized bandgap narrowing of 30–40 meV in the same regions, while cathodoluminescence spectroscopy linked the reduced potential in the core to CN defects, and suggested VGaON defect complexes as the most likely origin of the non-radiative wells at the core/shell interface.
These findings demonstrate that point defects can play a dominant role in shaping electrostatic potential landscapes and optical properties of GaN nanowires. Since such defects act as non-radiative recombination centers, they have critical implications for the efficiency and design of nanowire-based LEDs, lasers, and quantum devices. The study highlights the need for careful defect management in epitaxial growth and provides a roadmap for understanding defect-driven electronic behavior in other III-V core/shell heterostructures.