III-nitride light-emitting diodes (LEDs) exhibit an injection-dependent emission blueshift and linewidth broadening that is severely detrimental to their color purity. Due to the difficulty in experimentally isolating the various competing mechanisms, a complete understanding of this phenomenon is missing. Using first-principles multi-scale modelling, we examine the current-dependent spectral characteristics of polar III-nitride LEDs and compare directly to experimental measurements of devices fabricated with state-of-the art quantum wells. We find that the band-gap blueshift due to electrostatic screening of the polarization charge competes with the redshift due to exchange-correlation effects in the free-carrier plasma, and this cancellation is sensitive to the quantum-well thickness. Overall, we find that the injection dependence of the emission energy is determined by a complex interplay between phase-spacing filling and polarization-charge screening, which blueshift the emission energy, and many-body plasma renormalization, which redshifts the emission energy. On the other hand, we find that the linewidth broadening, and in particular the broadening of the high-energy tail, is predominantly due to phase-space filling. Designs that reduce the carrier density required to operate the LED at a given current density lessen their injection-dependent wavelength shift and linewidth broadening.

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III-氮化物发光二极管的注入相关发射蓝移和线宽展宽的起源

III 族氮化物发光二极管 (LED) 表现出与注入相关的发射蓝移和线宽展宽，这严重损害了它们的色纯度。由于难以通过实验分离各种竞争机制，因此缺乏对这种现象的完整理解。使用第一性原理多尺度建模，我们检查了极性 III 族氮化物 LED 的电流相关光谱特性，并直接与使用最先进的量子阱制造的器件的实验测量结果进行比较。我们发现，由于极化电荷的静电屏蔽引起的带隙蓝移与自由载流子等离子体中的交换相关效应引起的红移相互竞争，并且这种抵消对量子阱的厚度很敏感。全面的，我们发现发射能量的注入依赖性是由相位间距填充和极化电荷屏蔽之间的复杂相互作用决定的，这使发射能量蓝移，而多体等离子体重整化使发射能量红移。另一方面，我们发现线宽的展宽，特别是高能尾的展宽，主要是由于相空间填充。降低在给定电流密度下运行 LED 所需的载流子密度的设计会减少与注入相关的波长偏移和线宽展宽。我们发现线宽加宽，特别是高能尾的加宽，主要是由于相空间填充。降低在给定电流密度下运行 LED 所需的载流子密度的设计会减少与注入相关的波长偏移和线宽展宽。我们发现线宽加宽，特别是高能尾的加宽，主要是由于相空间填充。降低在给定电流密度下运行 LED 所需的载流子密度的设计会减少与注入相关的波长偏移和线宽展宽。