TECHNOLOGY FOR CHANGE

PRAM Aims to Replace Flash Memory

Researchers at the University of California Berkeley and the Lawrence Berkeley National Laboratory claim to have a nano-structured formulation that makes phase-change random access memory (PRAM) the prime candidate to replace flash. By storing bits as a phase-change in a polymer�from amorphous to crystalline�PRAM will achieve terabit densities on chips that can pack hundreds of full-length movies and whole libraries of books into our mobile devices.

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PRAM Aims to Replace Flash Memory
As flash memory becomes so dense that atomic-scale defects cause failure, many different approaches are being tried to replace the aging technology�from ferroelectric RAM (FRAM, which uses electrical polarization to enhance its DRAM-like bit cells) to magnetic RAM (MRAM, which stores information in magnetic bit cells).

The most promising alternative for future terabit chips, however, is phase-change RAM (PRAM). PRAM stores bits as an amorphous or crystalline state of its polymer bit cell.

Now a new formulation invented by researchers from the University of California (UC) Berkeley and the Lawrence Berkeley National Laboratory (Berkeley Lab) aims to enable PRAM to take the baton from flash memories and win the race to succeed it.

The new PRAM formulation is called a binary eutectic-alloy nanostructure (BEAN). BEAN has the potential to increase a PRAM's density far beyond flash, while improving performance with faster writes and lower power consumption, according to the UC and Berkeley Lab.

Diagram shows enthalpy curves sketched for the liquid, crystalline and amorphous phases of a new class of nanomaterials called "BEANs"�for binary eutectic-alloy nanostructures (source: Daryl Chrzan).

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