AlN:Er薄膜在不同退火温度下应力诱导的微观结构演变

摘要

The microstructure evolution of AlN: Er during thermal treatment was mainly characterized by weak beam diffraction-contrast imaging and high resolution phase-contrast imaging of the transmission electron micros-copy (TEM), which was also supported by X-ray diffraction (XRD) and Raman spectroscopy. Three regions could be observed in the TEM for the implanted samples. The region Ⅰ is about 30 nm in depth below the surface, the re-gion Ⅱ is about 50 nm in depth under the region I and is the worst damaged area, and the region Ⅲ is the area below the reigion Ⅱ. At relatively low annealing temperature, such as 1025℃, the regionI disappears. However, this area can be observed again after annealing at 1200℃.Based on the results of XRD, Raman and TEM, the interesting experiment phenomenon are explained on the view of damage recovery and stress releasing. There is a large stress in the region Ⅱ due to the large radius difference between Er ions and Ga ions. In the annealing process at 1025℃, the region Ⅰ is affected by the stress from region Ⅱ, the lattice distortion in region Ⅰ is produced. Therefore, the re-gion Ⅰ is observed as region Ⅱ under TEM observation. In the annealing process at 1200℃, the stress in the region Ⅰ is released from the surface, the lattice distortion is removed and the region Ⅰ is observed again under TEM.%以透射电镜中的弱束衍衬成像和高分辨相位衬度成像为主要表征手段,辅以X射线衍射、拉曼光谱等测试方法,对AlN:Er样品在退火过程中的微观结构演变过程进行了深入分析.在透射电镜观察下,Er离子注入的AlN样品在退火前存在三个区域:区域Ⅰ为自表面以下约30 nm深度;区域Ⅱ为区域I以下约50 nm深度;区域Ⅲ为区域Ⅱ以下的部分,其中区域Ⅱ为损伤最为严重的区域.在较低的温度(如1025℃时)退火后,区域Ⅰ消失;但1200℃退火后,又重新可以观察到区域Ⅰ.结合TEM、XRD和Raman测试结果,从损伤恢复和应力释放的角度对上述实验现象进行了理论解释:由于Er离子半径和基体原子半径的差异,在区域Ⅱ中引入较大的应力;在1025℃退火时,来自区域Ⅱ的应力作用于区域Ⅰ,导致区域Ⅰ发生大的晶格扭曲,和区域Ⅱ合并,用TEM观察不到;在1200℃退火时,应力在表面释放,区域Ⅰ的晶格扭曲修复,从而用TEM可重新观察到.