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Study of structural and optical properties of MBE grown nonpolar (10-10) ZnO/ZnMgO photonic structures
Optical Materials ( IF 3.8 ) Pub Date : 2020-02-01 , DOI: 10.1016/j.optmat.2020.109709
M. Stachowicz , J.M. Sajkowski , S. Kryvyi , A. Pieniazek , A. Reszka , A. Wierzbicka , M.A. Pietrzyk , E. Przezdziecka , D. Jarosz , K. Gwóźdź , E. Placzek-Popko , E. Alves , S. Magalhães , A. Kozanecki

Abstract Two types of simple monolithic photonic ZnO/ZnMgO structures, differing by a factor of two in thicknesses of individual components and grown on m-ZnO substrates, are tested to determine limitations in obtaining their good quality at Mg concentrations close to the limit for phase segregation (~40–45%). The studied structures were composed of 5.5 pairs of ZnO/ZnMgO bilayers (20/22 and 40/45 nm), the central ZnO microcavity (70 and 140 nm) and 5 bilayers on top. Actual layer thicknesses were verified using Scanning Electron Microscopy. Rutherford Backscattering Spectrometry was used to determine the Mg content. The X-ray rocking curves revealed high periodicity and proved that the wurtzite structure was retained without precipitates of foreign phases. Reciprocal space maps and the calculated lattice constants indicated that the layers were strained. Excitonic lines in cross-sectional cathodoluminescence (CL) spectra from individual ZnO layers are blue-shifted compared to emissions from ZnO substrates, thus confirming the presence of strain. The CL intensity of the first ZnMgO layers deposited on ZnO substrates and on both interfaces of the central microcavities was low thus suggesting an effective generation of misfit defects, especially in thicker structures. Reflectivity measurements confirmed the existence of cavity resonance at 385 nm and stop band at 370–400 nm in the photonic structure with a 140 nm microcavity. The results show that defect engineering at the initial stages of deposition of ZnMgO layers with high Mg is critical for the optimization of all-ZnO photonic structures.

中文翻译:

MBE 生长的非极性 (10-10) ZnO/ZnMgO 光子结构的结构和光学特性研究

摘要 测试了两种简单的单片光子 ZnO/ZnMgO 结构,它们的单个组件的厚度相差两倍,并且生长在 m-ZnO 衬底上,以确定在接近相位极限的 Mg 浓度下获得良好质量的限制。隔离(~40-45%)。研究的结构由 5.5 对 ZnO/ZnMgO 双层(20/22 和 40/45 nm)、中央 ZnO 微腔(70 和 140 nm)和顶部的 5 个双层组成。使用扫描电子显微镜验证实际层厚度。卢瑟福背散射光谱法用于确定镁含量。X 射线摇摆曲线显示出高周期性并证明纤锌矿结构得以保留,没有外来相的沉淀。倒易空间图和计算出的晶格常数表明这些层是应变的。与来自 ZnO 基板的发射相比,来自单个 ZnO 层的横截面阴极发光 (CL) 光谱中的激子线发生蓝移,从而证实了应变的存在。沉积在 ZnO 衬底上和中心微腔的两个界面上的第一层 ZnMgO 层的 CL 强度很低,因此表明错配缺陷的有效产生,尤其是在较厚的结构中。反射率测量证实在具有 140 nm 微腔的光子结构中存在 385 nm 的腔共振和 370-400 nm 的阻带。结果表明,高Mg ZnMgO 层沉积初始阶段的缺陷工程对于优化全ZnO 光子结构至关重要。与来自 ZnO 基板的发射相比,来自单个 ZnO 层的横截面阴极发光 (CL) 光谱中的激子线发生蓝移,从而证实了应变的存在。沉积在 ZnO 衬底上和中心微腔的两个界面上的第一层 ZnMgO 层的 CL 强度很低,因此表明错配缺陷的有效产生,尤其是在较厚的结构中。反射率测量证实在具有 140 nm 微腔的光子结构中存在 385 nm 的腔共振和 370-400 nm 的阻带。结果表明,高Mg ZnMgO 层沉积初始阶段的缺陷工程对于优化全ZnO 光子结构至关重要。与来自 ZnO 基板的发射相比,来自单个 ZnO 层的横截面阴极发光 (CL) 光谱中的激子线发生蓝移,从而证实了应变的存在。沉积在 ZnO 衬底上和中心微腔的两个界面上的第一层 ZnMgO 层的 CL 强度很低,因此表明错配缺陷的有效产生,尤其是在较厚的结构中。反射率测量证实在具有 140 nm 微腔的光子结构中存在 385 nm 的腔共振和 370-400 nm 的阻带。结果表明,高Mg ZnMgO 层沉积初始阶段的缺陷工程对于优化全ZnO 光子结构至关重要。
更新日期:2020-02-01
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