Effects of The Height of Nanorod Structure on The Photoluminescence Spectra of GaN-based Green LED
Author(s): HUANG Hua-mao, HUANG Jiang-zhu, HU Xiao-long, WANG Hong
Pages: 967-972
Year: 2016 Issue: 8
Journal: Chinese Journal of Luminescence
Keyword: GaN-based LED; green LED; nanorod structure; photoluminescence spectrum;
Abstract: Nanorod structure is an effective method to release the strain in multiple quantum wells of In-GaN/GaN green LED with high In component. In this paper, the natural lithography with self-assembled polystyrene microspheres, inductively coupled plasma dry etching and wet-etching using KOH aqueous solution were used to fabricate the nanorod structure with three heights in GaN-based green LED epitaxial wafers. The morphology was observed by scanning electron microscope, and the photoluminescence (PL) spectra at room temperature and 10 K low temperature were characterized. It is shown that the strain re-laxation significantly affect the piezoelectric field, thereby the nanorod structure leads to a promotion of the wafers'internal quantum efficiency (IQE) and blue-shift of the peak wavelengths of PL spectra, and the nonuniform distribution of the strain causes a broadening of the FWHM ( full width at half maxi-mum). Compared with the ordinary planar structure, the nanorod structure with the height of 747 nm in-duces an enhancement of 917% for the IQE, a blue-shift of 18 nm for the peak wavelengths of PL spec-trum, and a broadening of 7 nm for the FWHM. The results also indicate that the decreasing of effective active area of samples with nanorod structure may reduce the FWHM.
Pages: 967-972
Year: 2016 Issue: 8
Journal: Chinese Journal of Luminescence
Keyword: GaN-based LED; green LED; nanorod structure; photoluminescence spectrum;
Abstract: Nanorod structure is an effective method to release the strain in multiple quantum wells of In-GaN/GaN green LED with high In component. In this paper, the natural lithography with self-assembled polystyrene microspheres, inductively coupled plasma dry etching and wet-etching using KOH aqueous solution were used to fabricate the nanorod structure with three heights in GaN-based green LED epitaxial wafers. The morphology was observed by scanning electron microscope, and the photoluminescence (PL) spectra at room temperature and 10 K low temperature were characterized. It is shown that the strain re-laxation significantly affect the piezoelectric field, thereby the nanorod structure leads to a promotion of the wafers'internal quantum efficiency (IQE) and blue-shift of the peak wavelengths of PL spectra, and the nonuniform distribution of the strain causes a broadening of the FWHM ( full width at half maxi-mum). Compared with the ordinary planar structure, the nanorod structure with the height of 747 nm in-duces an enhancement of 917% for the IQE, a blue-shift of 18 nm for the peak wavelengths of PL spec-trum, and a broadening of 7 nm for the FWHM. The results also indicate that the decreasing of effective active area of samples with nanorod structure may reduce the FWHM.
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