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Quantifying the transverse-electric-dominant 260 nm emission from molecular beam epitaxy-grown GaN-quantum-disks embedded in AlN nanowires: a comprehensive optical and morphological characterization
Date
2020
Abstract
There has been a relentless pursuit of transverse electric (TE)-dominant deep ultraviolet (UV) optoelectronic devices for efficient surface emitters to replace the environmentally unfriendly mercury lamps. To date, the use of the ternary AlGaN alloy inevitably has led to transverse magnetic (TM)-dominant emission, an approach that is facing a roadblock. Here, we take an entirely different approach of utilizing a binary GaN compound semiconductor in conjunction with ultrathin quantum disks (QDisks) embedded in AlN nanowires (NWs). The growth of GaN QDisks is realized on a scalable and low-cost Si substrate using plasma-assisted molecular beam epitaxy as a highly controllable monolayer growth platform. We estimated an internal quantum efficiency of ∼81% in a wavelength regime of ∼260 nm for these nanostructures. Additionally, strain mapping obtained by high-angle annular dark-field scanning transmission electron microscopy is studied in conjunction with the TE and TM modes of the carrier recombination. Moreover, for the first time, we quantify the TE and TM modes of the PL emitted by GaN QDisks for deep-UV emitters. We observed nearly pure TE-polarized photoluminescence emission at a polarization angle of ∼5°. This work proposes highly quantum-confined ultrathin GaN QDisks as a promising candidate for deep-UV vertical emitters.
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Publisher
American Chemical Society
Citation
ACS Applied Materials Interfaces 2020, 12, 37, pp. 41649–41658
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Funding Information
We acknowledge the financial support from the King Abdulaziz City for Science and Technology (KACST) under grant no. KACST TIC R2-FP-008. This work was partially supported by the King Abdullah University of Science and Technology (KAUST) baseline funding no. BAS/1/1614-01-01 and MBE equipment funding no. C/M-20000-12-001-77 and KCR/1/4055-01-01