埋层应变对溅射生长Ge量子点的影响

Influences of buried strain on the growth of Ge quantum dots prepared by ion beam sputtering

利用离子束溅射制备双层Ge/Si量子点,通过变化Si隔离层厚度和Ge沉积量研究了埋层应变场对量子点生长的影响。实验中观察到隔离层厚度较薄时,双层结构中第2层量子点形成的临界厚度减小,生长过程提前;此外,随着Ge沉积量的增加,第2层量子点密度维持在一定范围,分布被调制的同时岛均匀长大呈现单模分布。增大隔离层厚度,埋层岛的生长模式在第2层岛生长时得到复制。通过隔离层传递的不均匀应变场解释了量子点生长模式的变化。

Double-layers Ge/Si quantum dot samples were grown on Si（100）substrate by ion beam sputtering system.The influence of buried strain on the growth of islands on the upper layer was studied by varying the thickness of Si spacer-layer and Ge deposition.When the thickness of spacer-layer was thin,the results show that a reduction of wetting-layer thickness of islands on the upper layer.In addition,with increasing the thick-ness of Ge deposition,the growth of islands on the second layer was modulated.Increasing the thickness of spacer-layer,the growth of islands on the second layer follows the buried dots.The change of growth mode was explained by the non-uniform strain field induced by the buried islands and passing through the spacer-layer.