Abstract The anisotropic exciton emission in a-plane nonpolar ZnO/ZnMgO MQWs offers opportunity for anisotropic photonic devices. By introducing Zn1-yMgyO buffer layer between r-plane sapphire substrate and MQWs, we investigated the structural and optical properties of ten-period a-plane ZnO/Zn1−xMgxO (ZnO/ZnMgO) multiple quantum wells (MQWs) with different widths of Zn1−xMgxO barrier layers grown by pulsed-laser deposition on Zn1-yMgyO buffered r-plane sapphire. Polarization-dependent photoluminescence spectra reveal that two additional linear polarizations of interface-bound exciton emission with E⊥c orienting at ~± 50° with respect to the regular a-plane MQWs are attributed to the generation of (0 0 0 2)-oriented nano-domains (NDs). As evidenced by XRD and TEM, we found four sets of (0 0 0 2)-oriented MQWs NDs are embedded in regular a-plane ZnO/ZnMgO MQWs with 90° in-plane rotation from one another which are inclined by 27.6° towards the [1 1 2 ¯ 0]-direction of the ZnO/ZnMgO MQWs. The existence of (0 0 0 2)-oriented NDs is further confirmed by the phase-contrast atomic force microscopy that modulates the optical anisotropy of interface-bound exciton emission in a-plane nonpolar ZnO/ZnMgO MQWs.

中文翻译：

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具有 Zn1-yMgyO 缓冲层的 a 面 ZnO/Zn1-xMgxO MQW 中界面束缚激子发射的光学各向异性

摘要 a 面非极性 ZnO/ZnMgO MQW 中的各向异性激子发射为各向异性光子器件提供了机会。通过在 r 面蓝宝石衬底和 MQW 之间引入 Zn1-yMgyO 缓冲层，我们研究了具有不同宽度的十周期 a 面 ZnO/Zn1−xMgxO (ZnO/ZnMgO) 多量子阱 (MQW) 的结构和光学性质。通过脉冲激光沉积在 Zn1-yMgyO 缓冲的 r 面蓝宝石上生长的 Zn1-xMgxO 阻挡层。偏振相关的光致发光光谱表明，界面束缚激子发射的两个附加线性偏振与 E⊥c 相对于规则 a 平面 MQW 取向在 ~±50° 归因于 (0 0 0 2) 取向的产生纳米域 (ND)。XRD 和 TEM 证明，我们发现四组 (0 0 0 2) 取向的 MQWs NDs 嵌入到规则的 a 面 ZnO/ZnMgO MQWs 中，面内旋转 90°，朝向 [1 1 2¯ 0 ]-ZnO/ZnMgO MQW 的方向。(0 0 0 2) 取向的 NDs 的存在通过相衬原子力显微镜进一步证实，该显微镜调节 a 面非极性 ZnO/ZnMgO MQW 中界面束缚激子发射的光学各向异性。