A high efficiency, high brightness, and robust micro or sub-microscale red light emitting diode (LED) is an essential, yet missing, component of the emerging virtual reality and future ultrahigh resolution mobile displays. We report, for the first time, to our knowledge, the demonstration of an N-polar InGaN/GaN nanowire sub-microscale LED emitting in the red spectrum that can overcome the efficiency cliff of conventional red-emitting micro-LEDs. We show that the emission wavelengths of N-polar InGaN/GaN nanowires can be progressively shifted from yellow to orange and red, which is difficult to achieve for conventional InGaN quantum wells or Ga-polar nanowires. Significantly, the optical emission intensity can be enhanced by more than one order of magnitude by employing an in situ annealing process of the InGaN active region, suggesting significantly reduced defect formation. LEDs with lateral dimensions as small as $\sim 0.75\mathrm{\mu m}$, consisting of approximately five nanowires, were fabricated and characterized, which are the smallest red-emitting LEDs ever reported, to our knowledge. A maximum external quantum efficiency $\sim 1.2\%$ was measured, which is comparable to previously reported conventional quantum well micro-LEDs operating in this wavelength range, while our device sizes are nearly three to five orders of magnitude smaller in surface area.

中文翻译：

---

N 极 InGaN/GaN 纳米线：克服发红光 micro-LED 的效率悬崖

高效率、高亮度和稳健的微型或亚微米级红色发光二极管 (LED) 是新兴虚拟现实和未来超高分辨率移动显示器必不可少但缺少的组件。据我们所知，我们首次报告了在红色光谱中发射 N 极 InGaN/GaN 纳米线亚微米级 LED 的演示，该 LED 可以克服传统红色发射 micro-LED 的效率悬崖。我们表明，N 极性 InGaN/GaN 纳米线的发射波长可以逐渐从黄色变为橙色和红色，这是传统 InGaN 量子阱或 Ga 极性纳米线难以实现的。重要的是，通过采用原位技术，可以将光发射强度提高一个数量级以上InGaN 有源区的退火工艺，表明缺陷形成显着减少。LED 的横向尺寸小至$～0.75\mathrm{微米}$由大约五根纳米线组成，据我们所知，这是有史以来最小的红色发光 LED。最大的外部量子效率$～1.2\%$测量，这与之前报道的在该波长范围内工作的传统量子阱微型 LED 相当，而我们的器件尺寸在表面积上小了近三到五个数量级。