Temperature-dependent residual stresses in a hetero-epitaxial thin film system

Abstract

This paper investigates the temperature dependence of residual stresses in a hetero-epitaxial thin film on a sapphire substrate. The X-ray diffraction technique was employed and a theoretical analysis was also carried out. It was found that the magnitude of compressive residual stresses decrease with increasing the temperature, and that the rate of the change can be well predicted theoretically. It was discovered, however, that the residual stresses vary with the film thickness. For a film of 0.3μm in thickness at all temperatures, the magnitudes of compressive stresses measured are greater than the theoretically predicted; but for that of 5μm in thickness, the magnitudes measured become smaller than the theoretical. This leads to the conclusion that the mitigation of lattice mismatch, essentially through interface misfit dislocations, could have varied with the change of the film thickness.