Evropeitsev Evgenii A, Kazanov Dmitrii R, Robin Yoann, Smirnov Alexander N, Eliseyev Ilya A, Davydov Valery Yu, Toropov Alexey A, Nitta Shugo, Shubina Tatiana V, Amano Hiroshi
Ioffe Institute, 26 Politekhnicheskaya, St Petersburg, Russia, 194021.
Institute of Materials and Systems for Sustainability (IMaSS), Nagoya University, Nagoya, Japan.
Sci Rep. 2020 Nov 4;10(1):19048. doi: 10.1038/s41598-020-76042-0.
Core-shell nanorods (NRs) with InGaN/GaN quantum wells (QWs) are promising for monolithic white light-emitting diodes and multi-color displays. Such applications, however, are still a challenge because intensity of the red band is too weak compared with blue and green. To clarify this problem, we measured photoluminescence of different NRs, depending on power and temperature, as well as with time resolution. These studies have shown that dominant emission bands come from nonpolar and semipolar QWs, while a broad yellow-red band arises mainly from defects in the GaN core. An emission from polar QWs located at the NR tip is indistinguishable against the background of defect-related luminescence. Our calculations of electromagnetic field distribution inside the NRs show a low density of photon states at the tip, which additionally suppresses the radiation of polar QWs. We propose placing polar QWs inside a cylindrical part of the core, where the density of photon states is higher and the well area is much larger. Such a hybrid design, in which the excess of blue radiation from shell QWs is converted to red radiation in core wells, can help solve the urgent problem of red light for many applications of NRs.
具有氮化铟镓/氮化镓量子阱（QW）的核壳纳米棒（NR）有望用于单片白光发光二极管和多色显示器。然而，此类应用仍然是一个挑战，因为与蓝色和绿色相比，红色波段的强度太弱。为了阐明这个问题，我们测量了不同纳米棒的光致发光，这取决于功率、温度以及时间分辨率。这些研究表明，主要发射带来自非极性和半极性量子阱，而一个宽的黄红色带主要源于氮化镓核中的缺陷。位于纳米棒尖端的极性量子阱的发射在与缺陷相关的发光背景下难以区分。我们对纳米棒内部电磁场分布的计算表明，尖端处的光子态密度较低，这进一步抑制了极性量子阱的辐射。我们建议将极性量子阱放置在核的圆柱形部分内，此处光子态密度较高且阱面积大得多。这种混合设计，即壳层量子阱中多余的蓝光辐射在核量子阱中转换为红光辐射，有助于解决纳米棒许多应用中急需的红光问题。
