Strain relief in epitaxial fluoride buffer layers for semiconductor heteroepitaxy

摘要

Strain in epitaxial BaF2layers grown by molecular beam epitaxy on CaF2covered Si is found to be completely relieved at room temperature in films thicker than sim;250 nm, despite a large lattice and thermal expansion mismatch. In thinner films, planar tensile strain up to 5times;10minus;3is observed. Partial or complete strain relief occurs during temperature cycling near room temperature, and even if further layers are grown on top of the BaF2film. This suggests that such films may be of use as buffers to relieve stresses in heteroepitaxial semiconductorhyphen;onhyphen;semiconductor structures.