International audienceCarbon-doped GeTe is a promising material for use in phase change memories since the addition of C increases the stability of the amorphous phase. By combining x-ray total scattering experiments and ab initio molecular dynamics, we show that carbon deeply modifies the structure of the amorphous phase through long carbon chains and tetrahedral and triangular units centered on carbon. A clear signature of these units is the appearance of an additional interatomic distance, around 3.3 angstrom in the measured pair distribution function. Besides, the first Ge-Ge and Ge-Te distances are almost not affected by doping. (C) 2011 American Institute of Physics. [doi:10.1063/1.3651321