Diffusion at the AlN/Al_0.3Ga_0.7N interface was investigated by X-ray diffraction, high-angle annular dark field scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. AlN/Al_0.3Ga_0.7N superlattices (SLs) have been grown at 800 °C on (111) silicon substrates by ammonia-assisted molecular beam epitaxy. Annealings on a 5-pair SL, carried out at the growth temperature in an ammonia-based atmosphere from 1h to 115h, show the occurrence of a diffusion process illustrated by the increase of the interface layer thickness. The cation interdiffusion is found to be weakly concentration-dependent while it seems to be more strain-dependent. The mean diffusion coefficient value determined in this study at the AlN/Al_0.3Ga_0.7N interface is about 6⨯10⁻¹⁸ cm²/s at the growth temperature. The effect of the unintentional annealing of buried layers during long growth runs is exemplified on a 45-pair SL. The measurement of the actual composition profile along the growth direction shows the formation of an unintentional AlGaN graded layer of intermediate composition at each interface. The thickness of each of these interfacial layers is found to decrease along the SL growth direction, pointing towards the influence of the overall time spent at growth temperature as a determining parameter.

通过X射线衍射，高角度环形暗场扫描透射电子显微镜和能量色散X射线光谱研究了AlN / Al _0.3 Ga _0.7 N界面处的扩散。AlN / Al _0.3 Ga _0.7 N超晶格（SLs）已通过氨辅助分子束外延在800°C下在（111）硅基板上生长。在生长温度下，在氨气中1h至115h进行的5对SL退火表明，界面层厚度的增加说明了扩散过程的发生。发现阳离子互扩散对浓度的依赖性很弱，而似乎对应变的依赖性更大。本研究中在AlN / Al下确定的平均扩散系数值在生长温度下，_0.3 Ga _0.7 N界面约为6×10 ^-18  cm ² / s。在45对SL上例举了长时间生长过程中埋层无意退火的影响。沿着生长方向的实际组成分布图的测量结果表明，在每个界面处都形成了中间组成的无意AlGaN渐变层。发现这些界面层中的每一个的厚度沿着SL生长方向减小，从而指出了在生长温度上花费的总时间的影响作为确定参数。