Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Austria.
Nanotechnology. 2011 Apr 22;22(16):165302. doi: 10.1088/0957-4484/22/16/165302. Epub 2011 Mar 11.
We show that both the morphology and the optoelectronic properties of SiGe islands growing in the pits of periodically pre-patterned Si(001) substrates are determined by the amount of Ge deposited per unit cell of the pattern. Pit-periods (p) ranging from 300 to 900 nm were investigated, and Ge growth was performed by molecular beam epitaxy (MBE) at temperatures of 690 and 760 °C. The ordered SiGe islands show photoluminescence (PL) emission, which becomes almost completely quenched, once a critical island volume is exceeded. By atomic force and transmission electron microscope images we identify the transition from pyramid-shaped to dome-shaped islands with increasing p. Eventually, the nucleation of dislocations in the islands leads to PL quenching. Below a critical Ge coverage a narrowing and a blue shift of the PL emission is observed, as compared to islands grown on a planar reference area of the same sample.
我们表明，在周期性预图案化的 Si(001) 衬底的凹坑中生长的 SiGe 岛的形态和光电特性取决于每个图案单元沉积的 Ge 量。研究了凹坑周期（p）范围为 300 至 900nm 的情况，并在 690 和 760°C 的温度下通过分子束外延（MBE）进行 Ge 生长。有序的 SiGe 岛显示出光致发光（PL）发射，一旦超过临界岛体积，PL 发射几乎完全被猝灭。通过原子力和透射电子显微镜图像，我们确定了随着 p 的增加，从金字塔形到圆顶形岛的转变。最终，在岛中发生位错的成核导致 PL 猝灭。与在同一样品的平面参考区域上生长的岛相比，在低于临界 Ge 覆盖的情况下，PL 发射会变窄和蓝移。
