UV LEDs based on p–i–n core–shell AlGaN/GaN nanowire heterostructures grown by N-polar selective area epitaxy
| Autor: | Todd E. Harvey, Matthew D. Brubaker, Kris A. Bertness, Bryan T. Spann, Alexana Roshko, Paul T. Blanchard, Kristen L. Genter |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Nanowire Bioengineering 02 engineering and technology Electroluminescence 010402 general chemistry Mole fraction 01 natural sciences Article law.invention Selective area epitaxy law Scanning transmission electron microscopy General Materials Science Electrical and Electronic Engineering Homojunction business.industry Mechanical Engineering Heterojunction General Chemistry 021001 nanoscience & nanotechnology 0104 chemical sciences Mechanics of Materials Optoelectronics 0210 nano-technology business Light-emitting diode |
| Zdroj: | Nanotechnology |
| ISSN: | 1361-6528 0957-4484 |
| DOI: | 10.1088/1361-6528/ab07ed |
| Popis: | Ultraviolet light-emitting diodes (UV LEDs) fabricated from N-polar AlGaN/GaN core-shell nanowires with p-i-n structure produced electroluminescence at 365 nm with ~5x higher intensities than similar GaN homojunction LEDs. The improved characteristics were attributed to localization of spontaneous recombination to the nanowire core, reduction of carrier overflow losses through the nanowire shell, and elimination of current shunting. Poisson-drift-diffusion modeling indicated that a shell Al mole fraction of x=0.1 in Al(x)Ga(1-x)N effectively confines electrons and injected holes to the GaN core region. AlGaN overcoat layers targeting this approximate Al mole fraction were found to possess a low-Al-content tip and high-Al-content shell, as determined by scanning transmission electron microscopy. Photoluminescence spectroscopy further revealed the actual Al mole fraction to be nanowire diameter dependent, where the tip and shell compositions converged towards the nominal flux ratio for large-diameter nanowires. |
| Databáze: | OpenAIRE |
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