Herein, the impact of high‐temperature (HT) annealing on the crystalline structure of metal organic vapor phase epitaxy (MOVPE)‐grown boron‐containing AlN layers is investigated. High‐resolution X‐ray diffraction studies reveal AlBN in the wurtzite configuration for nonannealed 300 nm‐thick layers containing several percent of boron. After 3 h of annealing at 1700 °C, the AlBN‐related reflex is weakened, showing a strong impact of the HT treatment on the crystalline structure of this material. After annealing, high‐resolution transmission electron microscopy micrographs reveal grain formation with moiré patterns, giving strong evidence of different crystal phases or orientations, alongside well‐oriented wurtzite regions. High‐angle annular dark‐field (HAADF) imaging and electron energy loss spectroscopy indicate stronger compositional inhomogeneities for the annealed sample in comparison with the as‐grown layer, most likely related to phase separation between AlN and BN. In addition, a significant diffusion of B out of the surface region is observed. AlBN with about ten times a lower boron content, for which defect propagation from the AlN template into the AlBN layer is visible, shows a much more homogeneous contrast in HAADF investigations after annealing, although the formation of granular structures is still observed.

中文翻译：

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高温退火对金属有机气相外延生长含硼AlN层的影响

在此，研究了高温（HT）退火对金属有机气相外延（MOVPE）生长的含硼AlN层晶体结构的影响。高分辨率X射线衍射研究表明，对于未退火的，包含百分之几硼的300 nm厚层，其纤锌矿结构中的AlBN。在1700°C下退火3小时后，与AlBN有关的反射减弱，这表明HT处理对该材料的晶体结构有很大影响。退火后，高分辨率透射电子显微镜显微照片显示出具有莫尔条纹的晶粒形成，为不同晶相或取向以及取向良好的纤锌矿区域提供了有力的证据。高角度环形暗场（HAADF）成像和电子能量损失谱表明，与成层相比，退火样品的成分不均匀性更强，这很可能与AlN和BN之间的相分离有关。另外，观察到B明显扩散出表面区域。退火后，尽管仍观察到颗粒结构的形成，但硼含量低约十倍的AlBN（从AlN模板到AlBN层的缺陷传播可见）显示出更加均匀的对比。