The influence of substitutional carbon on the Si Ge interdiffusion studiedby x-ray diffractometry at superlattice structures

Si/Ge interdiffusion in SiGe(C)/Si(C) superlattice (SL) structures with dif ferent positions and concentrations of substitutional carbon was studied un der atmospheric and high hydrostatic pressure in the temperature range 700- 950 degrees C for Ge (about 20%) and carbon (0-0.5%) concentrations, which are relevant for modem SiGe(C) device applications. The coefficient of the Si/Ge interdiffusion increases linearly with the carbon concentration and t he total amount of carbon in the SL structure. With increasing hydrostatic pressure a further increase of the diffusion was observed. Both effects cou ld be interpreted by a modification of the point defect spectrum with an un dersaturation of Si self-interstitials and a supersaturation of vacancies.