EU project Diaspora

Abu Sebastian
Martin Salinga


Phase-change materials have been used since the early 1990s in rewritable optical data storage. Research for better materials had led this technology to the successful introduction of consumer data storage devices like rewritable compact disks (CD), digital versatile disks (DVD), and Blu-ray disks (BD) or high-definition digital versatile disks (HD DVD). As an electronic memory, phase-change materials offer promising future prospects in terms of speed, scalability, and endurance. They could act as a so-called storage-class memory, filling the speed and endurance gap between DRAM (access time 60 ns) and Flash (write time 1 ms).

In 2012, IBM and SK Hynix announced a joint development agreement and a technology license agreement for the development of Phase Change Random Access Memory (or PCRAM) technology. There is already a hybrid PCM/NAND server flash card by IBM that has at least 12 times lower latency than an enterprise PCIe flash card.

In addition to the application as storage class memory, phase-change materials recently attracted interest in the field of brain inspired computing. Researchers aim at breaking the Von Neumann bottleneck due to memory and processor being separated by a data channel in conventional information-processing systems. Massive parallelism and energy efficiency of the human brain suggest a great source of inspiration for a non-conventional computer architecture.

Being more mature than technologies like resistive switching memory (RRAM) or conductive bridge memory (CBRAM), phase change memory was already implemented as a synaptic element in a large-scale neural network. In addition to its excellent scalability, the main characteristic of PCM that makes it a good candidate as a synaptic device is its capability to be programmed to intermediate resistance states between high and low-resistance values, similar to the MLC concept in storage technology.


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