This study systemically investigated the retardation of electrical-stress-induced degradation in Ge2Sb2Te5 by modifying its material properties through doping. The effects of doping on the electromigration and void formation in molten Ge2Sb2Te5 were explored by studying the model of a large and symmetric line-shaped Ge2Sb2Te5 cell doped with nitrogen, oxygen and bismuth, using high-amplitude electrical pulse stress. The electromigration rate, which was represented by the product of the diffusion coefficient and effective charge number (DZ*), and the amount of void formation in doped Ge2Sb2Te5 were quantified and compared with undoped Ge2Sb2Te5. The DZ* and void area in Bi-doped Ge2Sb2Te5 increased by about 10% compared with those in undoped Ge2Sb2Te5; these values decreased by 30% and 45% in the O- and N-doped Ge2Sb2Te5, respectively. The results suggested that the interstitial-type dopant could suppress the electromigration rate and void formation by decreasing the free volume; however, the substitutional-type dopant could not. The change in the free volume of molten Ge2Sb2Te5 due to dopants led to the change in the electromigration rate and the area of void formation. Understanding how the atomic-bonding type of dopants affected the degradation phenomena helps in designing phase-change material that was more stable against device failures.

Influence of Dopants on Atomic Migration and Void Formation in Molten Ge2Sb2Te5 under High-Amplitude Electrical Pulse. T.Y.Yang, J.Y.Cho, Y.J.Park, Y.C.Joo: Acta Materialia, 2012, 60[5], 2021-30