Photonic band characterization in InGaN/GaN nanocolumn arrays with triangular and honeycomb lattices by angle-resolved micro-photoluminescence measurements

Oto, Takao; Okamura, Masato; Matsui, Yuzo; Motoyama, Kai; Ishizawa, Shunsuke; Togashi, Rie; Kishino, Katsumi

doi:10.35848/1347-4065/abfeaa

Cited by 5 publications

(6 citation statements)

References 36 publications

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“…Specifically, ultrathin GaN nanowires (NWs) with diameters 20 nm are beneficial for achieving ultrafast switching in field-effect transistors [8,9], they can elastically relax large amounts of epitaxial strain [10][11][12][13], and they host dielectrically confined excitons up to room temperature [14]. If arranged deterministically on the substrate surface, such NW arrays can principally form photonic cavities [15] and they ease the parallel contacting of many single NWs [16]. Yet, the fabrication of such ordered arrays of ultrathin NWs remains to date an open challenge.…”

Section: Introductionmentioning

confidence: 99%

A route for the top-down fabrication of ordered ultrathin GaN nanowires

et al. 2023

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We introduce a facile route for the top-down fabrication of ordered arrays of GaN nanowires with aspect ratios exceeding 10 and diameters below 20 nm. Highly uniform thin GaN nanowires are first obtained by lithographic patterning a bilayer Ni/SiNx hard mask, followed by a combination of dry and wet etching in KOH. The SiNx is found to work as an etch stop during wet etching, which eases reproducibility. Arrays with nanowire diameters down to (33 ± 5) nm can be achieved with a uniformity suitable for photonic applications. Next, a scheme for digital etching is demonstrated to further reduce the nanowire diameter down to 5 nm. However, nanowire breaking or bundling is observed for diameters below ≈ 20 nm, an effect that is associated to capillary forces acting on the nanowires during sample drying in air. Explicit calculations of the nanowire buckling states under capillary forces indicate that nanowire breaking is favored by the incomplete wetting of water on the substrate surface during drying. The observation of intense nanowire photoluminescence at room-temperature indicates good compatibility of the fabrication route with optoelectronic applications. The process can be principally applied to any GaN/SiNx nanostructures and allows regrowth after removal of the SiNx mask.

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Section: Introductionmentioning

confidence: 99%

A route for the top-down fabrication of ordered ultrathin GaN nanowires

et al. 2023

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“…Specifically, ultrathin GaN nanowires (NWs) with diameters ≤ 20 nm are beneficial for achieving ultrafast switching in field-effect transistors [8,9], they can elastically relax large amounts of epitaxial strain [10-12], and they host dielectrically confined excitons up to room temperature [13]. If arranged deterministically on the substrate surface, such NW arrays can principally form photonic cavities [14] or interconnects [15].…”

Section: Introductionmentioning

confidence: 99%

A route for the top-down fabrication of ordered ultrathin GaN nanowires

Oliva¹,

Kaganer²,

Pudelski³

et al. 2022

Preprint

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Ultrathin GaN nanowires (NWs) are attractive to maximize surface effects and as building block in high-frequency transistors. Here, we introduce a facile route for the top-down fabrication of ordered arrays of GaN NWs with aspect ratios exceeding 10 and diameters below 20 nm. Highly uniform thin GaN NWs are first obtained by using electron beam lithography to pattern a Ni/SiN x hard mask, followed by dry etching and wet etching in hot KOH. The SiN x is found to work as an etch stop during wet etching in hot KOH. Arrays with NW diameters down to (33 ± 5) nm can be achieved with a yield exceeding 99.9 %. Further reduction of the NW diameter down to 5 nm is obtained by applying digital etching which consists in plasma oxidation followed by wet etching in hot KOH. The NW radial etching depth is tuned by varying the RF power during plasma oxidation. NW breaking or bundling is observed for diameters below ≈ 20 nm, an effect that is associated to capillary forces acting on the NWs during sample drying in air. This effect can be principally mitigated using critical point dryers. Interestingly, this mechanical instability of the NWs is found to occur at much smaller aspect ratios than what is predicted for models dealing with macroscopic elastic rods. Explicit calculations of buckling states show an improved agreement when considering an inclined water surface, as can be expected if water assembles into droplets. The proposed fabrication route can be principally applied to any GaN/SiN x nanostructures and allows regrowth after removal of the SiN x mask.

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“…A PlC with a honeycomb lattice [27][28][29] can accommodate GaN NCs with higher f than that with a triangular lattice for the same D and L values. Figures 1(a) and 1(b) show schematics of the NC lattice arrangement for triangular and honeycomb lattices, respectively, where a represents the distance between the nearest neighboring NCs.…”

mentioning

confidence: 99%

“…GaN NCs with various D values were selectively grown on the patterned template, followed by the deposition of five-period InGaN/ GaN layers on these NCs. 27,28) These NCs have InGaN-InGaN core-shell nanostructures, resulting in double-peak emission spectra. 19,23) To couple electron-hole pairs in the InGaN active layers into SPPs, we introduced Au-based PlCs onto the InGaN/GaN NCs using a previously reported procedure.…”

mentioning

confidence: 99%

Plasmonic red-light-emission enhancement by honeycomb-latticed InGaN/GaN ordered fine nanocolumn arrays

Oto,

Aihara,

Motoyama

et al. 2023

Appl. Phys. Express

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By using ordered fine nanocolumns suitable for high-efficiency red-emission, emission enhancement based on surface plasmon polariton (SPP) coupling was successfully obtained for the honeycomb lattice. This lattice enables obtaining a longer SPP resonant wavelength in the red region, which could not be attained for the triangular lattice. A 4.8-fold red-emission enhancement was achieved for the honeycomb lattice, demonstrating effective synergy between plasmonic and nanocrystalline effects within the red-emission nanocolumn system. Additionally, a 3.2-fold light-extraction enhancement was attained by changing the emission directionality by introducing plasmonic crystals (PlCs) in addition to metal reflection.

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Photonic band characterization in InGaN/GaN nanocolumn arrays with triangular and honeycomb lattices by angle-resolved micro-photoluminescence measurements

Cited by 5 publications

References 36 publications

A route for the top-down fabrication of ordered ultrathin GaN nanowires

A route for the top-down fabrication of ordered ultrathin GaN nanowires

A route for the top-down fabrication of ordered ultrathin GaN nanowires

Plasmonic red-light-emission enhancement by honeycomb-latticed InGaN/GaN ordered fine nanocolumn arrays

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