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采用晶体相场模型研究了异质外延过程中失配应变与应力弛豫对外延层界面形态演化的影响,并对由衬底倾角引起的外延层晶向倾侧进行了分析.研究结果表明:在有一定倾角的衬底晶体上进行外延生长时,若衬底和外延层之间失配度较大(ε>0.08),外延层中弹性畸变能会以失配位错的形式释放,最终薄膜以稳定的流动台阶形式生长且外延层的晶向倾角与衬底倾角呈近似线性关系.而当衬底和外延层之间失配度较小(ε<0.04)不足以形成失配位错时,外延层中弹性畸变能会以表面能的形式释放,最终使薄膜以岛状形态生长.在高过冷度条件下,衬底倾角和失配度较大时,衬底和外延层之间会形成由大量位错规则排列而成的小角度晶界从而显著改变外延层的生长位向.
The effects of mismatch strain and stress relaxation on the morphology evolution of the epitaxial layer during heteroepitaxy were investigated by using the crystal phase field model. The crystal orientation of the epitaxial layer caused by substrate tilt was analyzed. The results show that in the When epitaxial growth occurs on a tilted substrate crystal, if the mismatch between the substrate and the epitaxial layer is large (ε> 0.08), the elastic distortion in the epitaxial layer can be released as misfit dislocations. The final film And the crystal dip angle of the epitaxial layer has an approximately linear relationship with the substrate tilt angle.When the mismatch degree between the substrate and the epitaxial layer is small enough (ε <0.04) to form misfit dislocations, In the epitaxial layer, the elastic distortion energy will be released as surface energy and finally the thin film grows in the island shape. Under high undercooling conditions, when the substrate inclination angle and the mismatch degree are large, the difference between the substrate and the epitaxial layer The formation of a large number of dislocation rules arranged by the small-angle grain boundaries so as to significantly change the epitaxial layer growth orientation.