Dislocation densities in AlN layers grown on c‐plane sapphire and physical vapor transport‐grown AlN (PVT‐AlN) (0001) substrates, by metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE), respectively, are evaluated from the density of etch pits formed in sodium hydroxide (NaOH)/potassium hydroxide (KOH) eutectic heated to 450 °C. In the heteroepitaxial layers grown by MOVPE on the sapphire substrates, etch pits with different sizes are formed. Cross‐sectional transmission electron microscopy (TEM) observations reveal that the large, medium, and small pits, with densities of 1.4 × 10⁶, 2.6 × 10⁷, and 6.9 × 10⁹ cm⁻², respectively, correspond to screw, mixed, and edge dislocations, respectively. In contrast, in the homoepitaxial layers grown by HVPE on the PVT‐AlN substrates, only one kind of etch pit with uniform size corresponding to the edge dislocations is formed with a density of 10³–10⁴ cm⁻². Cross‐sectional TEM observation confirms that the edge dislocations in the homoepitaxial layer propagate from the substrate through the interface, which indicates that the dislocation density does not increase during homoepitaxial growth by HVPE. The HVPE‐AlN homoepitaxial layers grown on the PVT‐AlN substrates are found to have very low dislocation density.

中文翻译：

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AlN同质外延层和异质外延层中位错的研究

分别通过金属有机气相外延（MOVPE）和氢化物气相外延（HVPE）评估了在c面蓝宝石和物理气相传输生长的AlN（PVT-AlN）（0001）衬底上生长的AlN层中的位错密度。在加热到450°C的氢氧化钠（NaOH）/氢氧化钾（KOH）共晶中形成的蚀刻坑的密度。在通过MOVPE在蓝宝石衬底上生长的异质外延层中，形成了具有不同尺寸的蚀刻坑。横截面透射电子显微镜（TEM）的观察表明，大，中，和小的凹坑，为1.4×10密度⁶，2.6×10 ⁷和6.9×10 ⁹ 厘米^-2分别对应于螺丝，混合和边缘错位。相反，在HVPE在PVT-AlN衬底上通过HVPE生长的同质外延层中，仅形成一种尺寸与边缘位错相对应的，尺寸均匀的蚀刻坑，其密度为10 ³ –10 ⁴  cm ^-2。TEM横断面观察证实，同质外延层中的边缘位错从基板通过界面传播，这表明在HVPE的同质外延生长过程中，位错密度没有增加。发现在PVT-AlN衬底上生长的HVPE-AlN同质外延层的位错密度非常低。