650 ps SET speed in Ge2Sb2Te5 phase change memory induced by TiO2 dielectric crystal plane

Crystallization speed of phase change material is one of the main obstacles for the application of phase change memory (PCM) as storage class memory in computing systems, which requires the combination of nonvolatility with ultra-fast operation speed in nanoseconds. Here, we propose a novel approach to speed up crystallization process of the only commercial phase change chalcogenide Ge₂Sb₂Te₅ (GST). By employing TiO₂ as the dielectric layer in phase change device, operation speed of 650 ps has been achieved, which is the fastest among existing representative PCM, and is comparable to the programing speed of commercial dynamic random access memory (DRAM). Because of its octahedral atomic configuration, TiO₂ can provide nucleation interfaces for GST, thus facilitating the crystal growth at the determinate interface area. Ti–O–Ti–O four-fold rings on the (110) plane of tetragonal TiO₂ is critical for the fast-atomic rearrangement in the amorphous matrix of GST that enables ultra-fast operation speed. The significant improvement of operation speed in PCM through incorporating standard dielectric material TiO₂ in DRAM paves the way for the application of phase change memory in high performance cache-type data storage.