[en] Experimental/ ab initio calculations ; amorphous state ; carbon ; germanium compounds ; phase change materials ; phase change memories ; X-ray scattering/ phase change memories ; pair distribution function ; interatomic distance ; triangular units ; tetrahedral units ; long carbon chains ; ab initio molecular dynamics ; X-ray total scattering experiments ; amorphous phase ; amorphous GeTe phase change material ; carbon doping ; GeTe:C/ A6140 Structure of amorphous, disordered and polymeric materials A7870C X-ray scattering (condensed matter)/ GeTe:C/ss GeTe/ss Ge/ss Te/ss C/ss GeTe/bin Ge/bin Te/bin C/el C/dop
[en] Carbon-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 Aring in the measured pair distribution function. Besides, the first Ge-Ge and Ge-Te distances are almost not affected by doping.