Spontaneously-grown, self-aligned AlGaN nanowire ultraviolet light emitting diodes still suffer from low efficiency partially because of the strong surface recombination caused by surface states, i.e., oxidized surface and high density surface states. Several surface passivation methods have been introduced to reduce surface non-radiative recombination by using complex and toxic chemicals. Here, we present an effective method to suppress such undesirable surface recombination of the AlGaN nanowires via diluted potassium hydroxide (KOH) solution; a commonly used chemical process in semiconductor fabrication which is barely used as surface passivation solution in self-assembled nitride-based nanowires. The transmission electron microscopy investigation on the samples reveals almost intact nanowire structures after the passivation process. We demonstrated an approximately 49.7% enhancement in the ultraviolet light output power after 30-s KOH treatment on AlGaN nanowires grown on titanium-coated silicon substrates. We attribute such a remarkable enhancement to the removal of the surface dangling bonds and oxidized nitrides (Ga-O or Al-O bonds) at the surface as we observe the change of the carrier lifetime before and after the passivation. Thus, our results highlight the possibility of employing this process for the realization of high performance nanowire UV emitters.
Bibliographical noteKAUST Repository Item: Exported on 2021-09-14
Acknowledged KAUST grant number(s): BAS/1/1614-01-01, BAS/1/1664-01-01
Acknowledgements: We acknowledge the financial support from King Abdullah University of Science and Technology (KAUST) baseline funding, BAS/1/1614-01-01 and BAS/1/1664-01-01. Also, BSO, TKN, MKS and BJ gratefully acknowledge funding support from King Abdulaziz City for Science and Technology, grant no. KACST TIC R2-FP-008. The time-resolved PL measurements have been carried out and analyzed by M. M. Muhammed and I. S. Roqan.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering