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dc.contributor.authorKe, Wen-Chengen_US
dc.contributor.authorLee, Fang-Weien_US
dc.contributor.authorChiang, Chih-Yungen_US
dc.contributor.authorLiang, Zhong-Yien_US
dc.contributor.authorChen, Wei-Kuoen_US
dc.contributor.authorSeong, Tae-Yeonen_US
dc.date.accessioned2017-04-21T06:55:28Z-
dc.date.available2017-04-21T06:55:28Z-
dc.date.issued2016-12-21en_US
dc.identifier.issn1944-8244en_US
dc.identifier.urihttp://dx.doi.org/10.1021/acsami.6b10226en_US
dc.identifier.urihttp://hdl.handle.net/11536/132962-
dc.description.abstractA hybrid patterned sapphire substrate (hybrid-PSS) was prepared using an anodic aluminum oxide etching mask to transfer nanopatterns onto a conventional patterned sapphire substrate with microscale patterns (bare-PSS). The threading dislocation (TD) suppression of light-emitting diodes (LEDs) grown on a hybrid-PSS (HP-LED) exhibits a smaller reverse leakage current compared with that of LEDs grown on a bare-PSS (BP-LED). The strain-free GaN buffer layer and fully strained InGaN active layer were evidenced by cross-sectional Raman spectra and reciprocal space mapping of the X-ray diffraction intensity for both samples. The calculated piezoelectric fields for both samples are close, implying that the quantum-confined Stark effect was not a dominant mechanism influencing the electroluminescence (EL) peak wavelength under a high injection current. The bandgap shrinkage effect of the InGaN well layer was considered to explain the large red-shifted EL peak wavelength under high injection currents. The estimated LED chip temperatures rise from room temperature to 150 degrees C and 75 degrees C for BP-LED and HP-LED, respectively, at a 600-mA injection current. This smaller temperature rise of the LED chip is attributed to the increased contact area between the sapphire and the LED structural layer because of the embedded nanopattern. Although the chip generates more heat at high injection currents, the accumulated heat can be removed to outside the chip effectively. The high diffuse reflection (DR) rate of hybrid-PSS increases the escape probability of photons, resulting in an increase in the viewing angle of the LEDs from 130 degrees to 145 degrees. The efficiency droop was reduced from 46% to 35%, effects which can be attributed to the elimination of TDs and strain relaxation by embedded nanopatterns. In addition, the light output power of HP-LED at 360-mA injection currents exhibits a similar to 22.3% enhancement, demonstrating that hybrid-PSSs are beneficial to apply in high-power LEDs.en_US
dc.language.isoen_USen_US
dc.subjectlight-emitting diodeen_US
dc.subjectdislocationen_US
dc.subjectnanopatternsen_US
dc.subjectRamanen_US
dc.subjectelectroluminescenceen_US
dc.subjectdiffuse reflectionen_US
dc.subjectefficiency droopen_US
dc.titleInGaN-Based Light-Emitting Diodes Grown on a Micro/Nanoscale Hybrid Patterned Sapphire Substrateen_US
dc.identifier.doi10.1021/acsami.6b10226en_US
dc.identifier.journalACS APPLIED MATERIALS & INTERFACESen_US
dc.citation.volume8en_US
dc.citation.issue50en_US
dc.citation.spage34520en_US
dc.citation.epage34529en_US
dc.contributor.department電子物理學系zh_TW
dc.contributor.departmentDepartment of Electrophysicsen_US
dc.identifier.wosnumberWOS:000390728900042en_US
Appears in Collections:Articles