Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada. Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
Nanotechnology. 2019 Dec 13;30(50):504001. doi: 10.1088/1361-6528/ab4201. Epub 2019 Sep 6.
In this paper, the size-dependent optical and electrical properties of 365 nm InGaN/AlGaN ultraviolet micron-size light-emitting diodes (μLEDs) on c-plane sapphire substrates is investigated. The series resistance of the μLED increased from 20 Ω to 15 kΩ when the diameter of the device decreased from 150 to 3 μm. The ideality factor increased from 4 to 4.6 over the same range of diameters due to the increase in the defect density for the smaller μLEDs. Moreover, electroluminescence characterization showed a fixed and red-spectral-shift emission for the μLEDs with diameters smaller than 10 μm and larger than 15 μm, respectively. The red-shift was due to band-gap narrowing in InGaN/AlGaN multi-quantum wells as a result of self-heating at higher current densities in the larger diameter μLEDs. Due to an increase in the heat dissipation of devices with a high surface to volume ratio, the smaller diameter devices were found to have higher light extraction efficiency and no measurable emission spectrum shift.
本文研究了 c 面蓝宝石衬底上 365nm InGaN/AlGaN 紫外微尺寸发光二极管（μLED）的尺寸相关的光电特性。当器件直径从 150μm 减小到 3μm 时，μLED 的串联电阻从 20Ω 增加到 15kΩ。由于较小 μLED 的缺陷密度增加，肖特基势垒的理想因子从 4 增加到 4.6。此外，电致发光特性表明，对于直径小于 10μm 和大于 15μm 的 μLED，分别具有固定和光谱红移的发射。红移是由于在较大直径 μLED 中较高电流密度下的自加热导致 InGaN/AlGaN 多量子阱的能带隙变窄所致。由于高纵横比器件的散热增加，发现较小直径的器件具有更高的光提取效率，并且没有可测量的发射光谱位移。
