Ultraviolet-A (UVA) micro-LEDs are increasingly garnering attention in fields such as additive manufacturing. However, the majority of these devices currently use heteroepitaxial substrates, where high stress from lattice mismatch leads to strong polarization and high dislocation densities, severely limiting the optoelectronic performance. This letter explores the characteristics of homoepitaxially grown UVA micro-LEDs with sizes down to $3~\mu \text{m}$ . At the material level, we report an in-plane compressive stress of 0.043 GPa and a dislocation density of $10^{{6}}$ cm−2, which is two to three orders of magnitude lower than that of traditional hetero-epitaxial substrates. At the device level, we examine the size effects from $100~\mu \text{m}$ down to $3~\mu \text{m}$ . The ideality factor and series resistance can reach a minimum value of 1.43 and $4.85~\Omega $ respectively. Owing to the enhanced crystal quality, all devices exhibit stable emission wavelengths, minimal efficiency droop, and uniform emission across the entire surface.

中文翻译：

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低位错密度同质外延 UV-A Micro-LED 尺寸缩小至 3 μm

紫外线 A (UVA) micro-LED 在增材制造等领域越来越受到关注。然而，目前这些器件大多数使用异质外延衬底，晶格失配产生的高应力导致强极化和高位错密度，严重限制了光电性能。这封信探讨了尺寸小至以下的同质外延生长的 UVA micro-LED 的特性 $3~\mu \text{m}$ 。在材料层面，我们报告面内压应力为 0.043 GPa，位错密度为 $10^{{6}}$cm−2，比传统异质外延基板低两到三个数量级。在设备级别，我们检查尺寸效应 $100~\mu \text{m}$向下 $3~\mu \text{m}$ 。理想因子和串联电阻可以达到最小值1.43， $4.85~\欧米茄 $分别。由于晶体质量的提高，所有器件都表现出稳定的发射波长、最小的效率下降以及整个表面的均匀发射。