Toward red light emitters based on InGaN-containing short-period superlattices with InGaN buffers

In order to broaden the light emission of nitride quantum structures towards the red color, the technological problem of low In incorporation in InGaN−based heterostructures has to be solved. To overcome this problem superlattices grown on InGaN buffers with different In content were used. Based on the comparison of the calculated ab initio superlattice band gaps with the photoluminescence emission energies obtained from the measurements on the specially designed samples grown by metal-organic vapor phase epitaxy, it is shown that by changing the superlattice parameters and the composition of the buffer structures, the light emission can be shifted to lower energies by about 167 nm (0.72 eV) in comparison to the case of a similar type of superlattices grown on GaN substrate. The importance of using superlattices to achieve red emission and the critical role of the InGaN buffer are demonstrated.The names of the individual files correspond to the numbering of the figures in the paper Staszczak, G.; Gorczyca, I.; Grzanka, E.; Smalc-Koziorowska, J.; Targowski, G.; Suski, T. Toward Red Light Emitters Based on InGaN-Containing Short-Period Superlattices with InGaN Buffers. Materials 2023, 16, 7386. https://doi.org/10.3390/ma16237386.Files included in this collection:Fig1 - Scheme of the calculated mInxGa1−xN/nInyGa1−yN SLs grown on thick buffer layer. QW layers are in red, and the QB layers are in blue color.Fig2a, 2b, 2c - Calculated band gaps, Eg, vs. number of barrier MLs, n, for a set of SLs: (a) mIn0.33Ga0.67N/nGaN, (b) mIn0.33Ga0.67N/nIn0.165Ga0.835N, (c) mIn0.33Ga0.67N/nIn0.25Ga0.75N.Fig3 - Calculated band gap for In0.33Ga0.67N/nGaN, mIn0.33Ga0.67N/In0.165Ga0.835N, and mIn0.33Ga0.67N/nIn0.25Ga0.75N SLs vs. In content in a buffer.Fig4 - Scheme of the investigated mInxGa1−xN/nInyGa1−yN superlattices grown on buffer layer with z~0.17, and z~0.2 of In content; m, n denotes the number of QW and QB MLs, respectively. The thickness of one ML is around 0.26 nm.Fig5a, 5b - The XRD patterns depict the characteristics of two samples: (a) sample A1 of InGaN/GaN SL (no indium in QBs), (b) sample A3 of InGaN/InGaN SL (with 15% In in QBs).Fig6a, 6b, 6c, 6d - Comparison of XRD reciprocal space maps around the asymmetric GaN (10–14) reflection for (a) sample A1 and (b) sample A3 with the corresponding structures grown on GaN (c,d).Fig7 - Cross-sectional TEM image of the mInGaN/nInGaN SLs with m = 2 and n = 30 MLs grown on In0.17Ga0.72N buffer layer (sample A3).Fig 8a, 8b - Comparison of PL spectra @20K of the selected InxGa1−xN/InyGa1−yN SLs: (a) sample A1 without indium in QBs (y = 0), (b) sample B1 with indium in QBs (y = 0.17).Fig9a, 9b - Comparison of the calculated SL band gaps, Eg, and PL emission energies. For (a) SLs 33/0 on buffers: GaN and In0.165Ga0.835N (blue line). (b) SLs 33/16.5 (green line) and 33/25 (violet line) on buffers: GaN and In0.165Ga0.835N and In0.33Ga0.67N.

为拓宽氮化物量子结构的红光发射光谱范围，亟需解决InGaN基异质结构中铟（Indium, In）掺入率偏低的核心技术难题。为克服该瓶颈，本研究采用了在不同铟组分InGaN缓冲层上外延生长的超晶格（superlattice）结构。通过将从头算（ab initio）方法得到的超晶格带隙，与通过金属有机气相外延（metal-organic vapor phase epitaxy）制备的定制样品的实测光致发光（photoluminescence）发射能量进行对比分析，结果表明：相较于在GaN衬底上生长的同类超晶格，通过优化超晶格参数与缓冲层结构组分，可将材料的光发射波长向低能方向偏移约167 nm（0.72 eV）。本研究证实了采用超晶格结构实现红光发射的技术价值，以及InGaN缓冲层在体系中的关键调控作用。本数据集包含的文件命名与论文Staszczak, G.; Gorczyca, I.; Grzanka, E.; Smalc-Koziorowska, J.; Targowski, G.; Suski, T. 发表于《Materials》2023年第16卷第7386页的论文中附图谱的编号一一对应，该论文DOI为："https://doi.org/10.3390/ma16237386"，论文标题为《基于含InGaN缓冲层的InGaN短周期超晶格的红光发射器件研究》。各文件详情如下：Fig1：厚缓冲层上生长的mInₓGa₁₋ₓN/nInᵧGa₁₋ᵧN超晶格结构示意图。其中量子阱（quantum well, QW）层以红色标注，势垒（quantum barrier, QB）层以蓝色标注。Fig2a、2b、2c：三类超晶格的计算带隙E_g随势垒单层（monolayer, ML）数n的变化关系：(a) mIn₀.₃₃Ga₀.₆₇N/nGaN；(b) mIn₀.₃₃Ga₀.₆₇N/nIn₀.₁₆₅Ga₀.₈₃₅N；(c) mIn₀.₃₃Ga₀.₆₇N/nIn₀.₂₅Ga₀.₇₅N。Fig3：mIn₀.₃₃Ga₀.₆₇N/nGaN、mIn₀.₃₃Ga₀.₆₇N/In₀.₁₆₅Ga₀.₈₃₅N以及mIn₀.₃₃Ga₀.₆₇N/nIn₀.₂₅Ga₀.₇₅N三类超晶格的计算带隙随缓冲层铟组分的变化规律。Fig4：在铟组分z≈0.17与z≈0.2的缓冲层上生长的mInₓGa₁₋ₓN/nInᵧGa₁₋ᵧN超晶格结构示意图，其中m、n分别代表量子阱与势垒的单层数，单个单层的厚度约为0.26 nm。Fig5a、5b：两款样品的X射线衍射（X-ray diffraction, XRD）图谱特征：(a) 样品A1为InGaN/GaN超晶格（势垒层无铟掺入）；(b) 样品A3为InGaN/InGaN超晶格（势垒层铟组分占比15%）。Fig6a、6b、6c、6d：围绕GaN(10–14)非对称反射的X射线倒易空间图对比：(a) 样品A1、(b) 样品A3，以及分别在GaN衬底上生长的对应结构(c、d)。Fig7：在In₀.₁₇Ga₀.₇₂N缓冲层上生长的m=2、n=30单层的mInGaN/nInGaN超晶格的截面透射电子显微镜（transmission electron microscopy, TEM）图像（样品A3）。Fig8a、8b：20K低温下所选InₓGa₁₋ₓN/InᵧGa₁₋ᵧN超晶格的光致发光光谱对比：(a) 势垒层无铟掺入的样品A1（y=0）；(b) 势垒层含铟掺入的样品B1（y=0.17）。Fig9a、9b：超晶格计算带隙E_g与光致发光发射能量的对比结果：(a) 缓冲层为GaN与In₀.₁₆₅Ga₀.₈₃₅N的33/0型超晶格（蓝色曲线）；(b) 缓冲层为GaN、In₀.₁₆₅Ga₀.₈₃₅N与In₀.₃₃Ga₀.₆₇N的33/16.5型（绿色曲线）与33/25型（紫色曲线）超晶格。