Bojarska-Cieślińska Agata, Marona Łucja, Smalc-Koziorowska Julita, Grzanka Szymon, Weyher Jan, Schiavon Dario, Perlin Piotr
Institute of High Pressure Physics, "Unipress", Sokolowska 29/37, 01-142, Warsaw, Poland.
TOP-GAN Limited, Solec 24/90, 00-403, Warsaw, Poland.
Sci Rep. 2021 Jan 8;11(1):21. doi: 10.1038/s41598-020-79528-z.
In this work we investigate the role of threading dislocations in nitride light emitters with different indium composition. We compare the properties of laser diodes grown on the low defect density GaN substrate with their counterparts grown on sapphire substrate in the same epitaxial process. All structures were produced by metalorganic vapour phase epitaxy and emit light in the range 383-477 nm. We observe that intensity of electroluminescence is strong in the whole spectral region for devices grown on GaN, but decreases rapidly for the devices on sapphire and emitting at wavelength shorter than 420 nm. We interpret this behaviour in terms of increasing importance of dislocation related nonradiative recombination for low indium content structures. Our studies show that edge dislocations are the main source of nonradiative recombination. We observe that long wavelength emitting structures are characterized by higher average light intensity in cathodoluminescence and better thermal stability. These findings indicate that diffusion path of carriers in these samples is shorter, limiting the amount of carriers reaching nonradiative recombination centers. According to TEM images only mixed dislocations open into the V-pits, usually above the multi quantum wells thus not influencing directly the emission.
在这项工作中，我们研究了不同铟组分的氮化物发光器件中穿透位错的作用。我们将在低缺陷密度GaN衬底上生长的激光二极管的特性与其在相同外延工艺下在蓝宝石衬底上生长的对应器件的特性进行了比较。所有结构均通过金属有机气相外延生长，发射波长范围为383 - 477nm的光。我们观察到，对于在GaN上生长的器件，整个光谱区域的电致发光强度都很强，但对于在蓝宝石上生长且发射波长小于420nm的器件，其电致发光强度迅速下降。我们根据位错相关的非辐射复合对低铟含量结构的重要性增加来解释这种行为。我们的研究表明，刃型位错是非辐射复合的主要来源。我们观察到，长波长发射结构在阴极发光中具有较高的平均光强度和更好的热稳定性。这些发现表明，这些样品中载流子的扩散路径较短，限制了到达非辐射复合中心的载流子数量。根据透射电子显微镜图像，只有混合位错会通向V形坑，通常在多量子阱上方，因此不会直接影响发光。
