Analysis of Polarization-Dependent Light Extraction and Effect of Passivation Layer for 230-nm AlGaN Nanowire Light-Emitting Diodes
This paper investigates the polarization-dependent light extraction efficiency (<inline-formula> <tex-math notation="LaTeX">$\eta _{\rm extraction}$</tex-math></inline-formula>) and the effect of passivation layer for AlGaN-based nanowire (NW) deep-ultraviolet (DUV)...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
IEEE
2017-01-01
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| Series: | IEEE Photonics Journal |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/7944547/ |
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| Summary: | This paper investigates the polarization-dependent light extraction efficiency (<inline-formula> <tex-math notation="LaTeX">$\eta _{\rm extraction}$</tex-math></inline-formula>) and the effect of passivation layer for AlGaN-based nanowire (NW) deep-ultraviolet (DUV) light-emitting diodes (LEDs) emitted at 230 nm using three-dimensional finite-difference time-domain method. Our results show that the use of NW structure for 230-nm LEDs can result in higher transverse-magnetic (TM) polarized <inline-formula><tex-math notation="LaTeX">$\eta _{\rm extraction}$</tex-math></inline-formula> than transverse-electric (TE) polarized <inline-formula> <tex-math notation="LaTeX">$\eta _{\rm extraction}$</tex-math></inline-formula>. Specifically, <inline-formula> <tex-math notation="LaTeX">$\eta _{\rm extraction}$</tex-math></inline-formula> up to ∼48% for TM polarization and ∼41% for TE polarization can be achieved by the investigated 230-nm NW LEDs as compared to conventional planar LEDs (∼0.2% and ∼2% for TM- and TE-polarizations, respectively) attributed to the large surface-to-volume ratio and strong sidewall emissions. In addition, the analysis on the effect of various passivation layer materials suggests the use of SiO<sub>2</sub>, which has smaller refractive index than the NW core, could extract more photons out of the NW core and lead to TM-polarized <inline-formula><tex-math notation="LaTeX"> $\eta _{\rm extraction}$</tex-math></inline-formula> up to ∼47%. Therefore, the use of the AlGaN NW structure is expected to lead to high external quantum efficiency DUV LEDs due to the large TM-polarized <inline-formula><tex-math notation="LaTeX">$\eta _{\rm extraction}$</tex-math></inline-formula> in combination with the dominant TM-polarized spontaneous emissions at 230 nm. |
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| ISSN: | 1943-0655 |