Influence of strain on solid–liquid phase equilibrium in heteroepitaxy of SiGe/Si(0 0 1)

A heteroepitaxially grown layer with a lattice constant different from that of substrate is subject to strain. If this strain cannot be released by misfit dislocations or surface undulation a pseudomorphic strained layer with lattice relaxation in growth direction will be formed. A simple model has been outlined to involve this strain energy into liquid–solid phase equilibrium calculations. The calculations have been applied to a SiGe layer on a Si(001) substrate grown from a ternary metallic solution with bismuth as solvent. The Ge amount has been varied. An increasing germanium content in the liquid phase leads to an additional supercooling necessary to balance out the rising strain in the solid layer. Moreover, the germanium content in the solid will shift to lower values in response to strain.

晶格常数不同于衬底的异质外延生长层会受到应变。如果这种应变不能通过失配位错或表面起伏释放，就会形成在生长方向上晶格弛豫的赝晶应变层。已经概述了一个简单模型，将这种应变能纳入液 - 固相平衡计算中。这些计算已应用于以铋为溶剂的三元金属溶液在Si(001)衬底上生长的SiGe层，其中锗的含量是变化的。液相中锗含量的增加导致需要额外的过冷来平衡固体层中不断增加的应变。此外，固体中的锗含量会因应变而降低。