Abstract The optical properties of GaN-based green light-emitting diodes (LED) are investigated by transmission electron microscopy (TEM) and temperature-dependent micro-photoluminescence (μ-TDPL) in this study. Compared with the emission of normal c-plane multiple quantum wells (C-MQWs), the emission of C-MQWs close to V-shaped pits (V-pits) exhibits a shoulder peak phenomenon at cryogenic temperature, and the shoulder peak gradually disappears as the temperature increases. At room temperature, the peak of C-MQWs close to V-pits (C2) exhibits a red-shift. The formation of V-pits would induce strain relaxation. Strain relaxation can result in Indium (In) incorporation and localization, and reduced quantum-confined stark effects (QCSE). In incorporation and localization can lead to the red-shift of C2, reduced QCSE can cause the blue-shift of C2. Therefore, the red-shift of C2 arises from further In incorporation and localization of C-MQWs. It is worth noting that In incorporation and localization is dominant in the formation of V-pits for green InGaN/GaN C-MQWs. Additionally, the carriers limited in sidewall MQWs (S-MQWs) of V-pits escape into C-MQWs close to V-pits can mitigate the common phenomenon in which the emission intensity of C-MQWs decreases as the temperature increases, which helps improve the emission intensity of GaN-based green LEDs.

中文翻译：

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V形凹坑对GaN基绿色发光二极管光学性能的影响

摘要 本研究通过透射电子显微镜 (TEM) 和温度相关微光致发光 (μ-TDPL) 研究了 GaN 基绿色发光二极管 (LED) 的光学特性。与普通c面多量子阱（C-MQWs）的发射相比，靠近V形凹坑（V-pits）的C-MQWs的发射在低温下呈现肩峰现象，肩峰逐渐消失随着温度的升高。在室温下，靠近 V 坑 (C2) 的 C-MQW 的峰值表现出红移。V 凹坑的形成会引起应变松弛。应变弛豫可导致铟 (In) 掺入和定位，并减少量子限制的斯塔克效应 (QCSE)。在掺入和定位中会导致 C2 的红移，降低 QCSE 会导致 C2 的蓝移。因此，C2 的红移源于 C-MQW 的进一步掺入和定位。值得注意的是，In 掺入和定位在绿色 InGaN/GaN C-MQW 的 V 凹坑形成中起主导作用。此外，限制在 V 坑侧壁 MQW (S-MQW) 中的载流子逃逸到靠近 V 坑的 C-MQW 中，可以缓解 C-MQW 的发射强度随温度升高而降低的常见现象，有助于改善GaN 基绿色 LED 的发射强度。