Investigation of the high temperature behavior of strained Si1−yCy /Si heterostructures

Abstract
We report on x‐ray diffraction measurements of the substitutional carbon content y in pseudomorphic Si1−yCy (yin situ by an x‐ray powder diffractometer. Despite the tensile strain in the 100‐nm‐thick layers and the high carbon supersaturation, the samples were stable up to 800 °C. Beyond this temperature range, the substitutional carbon content decreased exponentially during isothermal annealing. This effect can be explained by the precipitation of the carbon and the nucleation and diffusion limited growth of SiC nanocrystals. Since no strain relief by the introduction of misfit dislocations was detectible, we conclude that contrary to the mechanism of strain relief in Si1−xGex, in comparably strained Si1−yCy epilayers, the main high temperature process is precipitation.