(a) Memory cell resistance vs. applied voltage curves in Cr2Ge2Te6 and GST memory cell. (b) Comparison of operation energy between Cr2Ge2Te6 and GST. Credit: Shogo Hatayama
A team of researchers at Tohoku University, in collaboration with the National Institute of Advanced Industrial Science and Technology (AIST) and Hanyang University, has developed new phase change material which has electrical characteristics that behave differently to those of conventional materials.
This new material allows a drastic reduction in power consumption for data-recording in non-volatile random access memory.
Phase change random access memory, PCRAM, has attracted attention as a next generation practical non-volatile memory. PCRAM isexpected to not only replace flash memory but also to be used for storage-class memory, which can mitigate the difference in latencies between DRAM and flash memory.
The principle of PCRAM operation relies on the change in electrical resistance between high resistance amorphous and low resistance crystalline states in phase change material.
Ge-Sb-Te (GST) is well known as a phase change material for PCRAM application.
GST can operate at high speed but has poor data retention at high temperatures (~ 85 ?C) and needs a large amount of power for data-recording.
This newly developed material, Cr2Ge2Te6 phase change material exhibits an inverse resistance change from low resistance amorphous to high resistance crystalline states. The researchers demonstrated that the Cr2Ge2Te6 can achieve a reduction of more than 90% in power consumption for data-recording compared to using conventional GST memory cell.
Simultaneously, Cr2Ge2Te6 was found to combine a faster operation speed (~30 ns) and a higher data retention property (over 170 ?C) than conventional materials. Comparison with other reported materials indicates that Cr2Ge2Te6 can break the trade-off relationship between data retention and operation speed.
The researchers believe that the inverse resistance change Cr2Ge2Te6 is a breakthrough material for PCRAM with combined low operation energy, high data retention and fast operation speed.
