Thin Film Growth around Misfit Dislocations

近年来，Si/Ge异质结在Si基电子和空穴的二维限制以及量子点的自组装方面受到了广泛的关注。这些应用的关键是应变异质界面的生长模式的控制。然而，Si_<1-x>Ge_x（001）表面上Si层生长的细节仍然没有得到很好的研究。本文报道了利用STM在Si_<1-x>Ge_x/Si（001）表面生长Si层的研究。首先，我们观察了<1-x>在Si（001）衬底上生长的不同厚度的Si_ Ge_x（001）层的表面形貌。0.46nm厚的Si 1-xGex层的表面在2x 1重构中包括许多二聚体空位。然而，台阶密度足够小以保持表面平坦，如Si（001）衬底。随着厚度的增加，二聚体空位沿直线排列，从而释放Si_<1-x>Ge_x（001）表面的压应变。二聚体空位线之间的距离减小到8a（a是表面空位）。 ...更多信息 在<1-x>厚度为1.38nm的Si_ Ge_x层上，由于二聚体空位线的存在，表面形成了小的台阶，使得表面不平整。与Si（001）2x 1表面相比，SA台阶趋于粗糙，而SB台阶变得直。在厚度大于2nm的Si_xGex层表面，观察到具有（105）晶面的三维锥形岛形核，在Si沉积过程中，在0.46nm的Si_ Ge_x（001）层上，二聚体空位消失，并在初始阶段出现许多小台阶<1-x>。随着Si的进一步沉积，台阶尺寸变大，表面恢复光滑。在<1-x>厚度为1.38nm的Si_ Ge_x（001）层上，沉积Si后，片状小台阶消失，表面变得更加光滑。但是，二聚体空位线仍然存在的Si覆盖到1 nm，可能是由于Ge的偏析。在会议上，将介绍更多关于Si_ Ge_x（001）表面上生长的Si层的形态变化的细节<1-x>，并将从生长前沿的应变积累和释放以及Ge外扩散的角度进行讨论。少

Si/Ge hetero-structure has been paid much attention in Si-based two-dimensional confinement of electrons and holes, and also in self assembling of quantum dots recently. A key of these applications is the control of the growth mode at the strained hetero-interfaces. However, a detail of the Si layers growth on the Si_<1-x>Ge_x (001 ) surface is still not well investigated. Here, we report our study on the growth of Si layers on Si_<1-x>Ge_x/Si (001) surfaces using STM.First, we observed the surface morphology of the Si_<1-x>Ge_x (001) layers of various thickness grown on the Si (001) substrates. The surface of the 0.46nm thick Sil-xGex layer include many dimer vacancies in the 2x1 reconstruction. However, the step density was small enough to keep the surface flat as the Si (001) substrate. Increasing the thickness, the dimer vacancies aligned to lines to release the compressive strain on the Si_<1-x>Ge_x (001) surface. The distance between dimer vacancy lines reduced to 8a (a is the su … More rface unit cell length) on the Si_<1-x>Ge_x layer of 1.38nm thickness.On the surface with dimer vacancy lines, small terraces stacked to make the surface uneven. SA step tended to be rough while SB step became straight in contrast to the Si (001) 2x1 surface. At the surface of the Sil-xGex layer with the thickness over 2nm, pyramidal 3D islands with (105) facets were observed to nucleate.In Si deposition, the dimer vacancies disappeared and many small terraces appeared in the initial stage on the Si_<1-x>Ge_x (001) layer of 0.46nm thickness. The terrace size became larger and the surface recovered smoothness in further deposition of Si. On the Si_<1-x>Ge_x (001) layer of 1.38nm thickness, patchy small terraces disappeared and the surface became smoother in the Si deposition. But, the dimer vacancy lines still persisted for the Si coverage up to 1nm, probably due to the segregation of Ge. In the conference, more details of the morphological change on the Si layers grown on the Si_<1-x>Ge_x (001) surface will be presented, and will be discussed from the viewpoints of the accumulation and release of stain and Ge out-diffusion on the growth front. Less