Plastic deformation and fracture resulting from stresses caused by differential thermal contraction in GaP/Si heterostructures

Cleavage cracks form in thick (≳5 μm) GaP layers deposited epitaxially on Si during the cooldown after growth. The distribution of stresses caused by differential thermal contraction in such heterostructures has been analyzed, and suggests that stress relief through plastic deformation explains why GaP layers thinner than 5 μm do not crack. Large-area, crack-free layers thicker than 5 μm have been grown on Si-on-sapphire substrates because the resultant stresses in the GaP layers are compressive rather than tensile.