Phase-Change Materials can Make Computers Faster, Greener

Replacing silicon with 'phase-change materials' (PCMs) can make future computers faster, efficient and 'greener' than the current ones, researchers at the University of Cambridge said.

PCMs are capable of switching between two structural phases with different electrical states - one glassy and insulating and the other crystalline and conducting. The phase switches occur in a billionth of a second. The researchers said that using these new materials can make computers 1,000 times faster than current models.

The team found that combinations of ultra-short voltage pulses can be used to perform logic-processing operations in non-volatile memory cells in PCM devices. Such operations can't be done on regular, silicon-based devices.

Unlike conventional computers, logic operations and memory are co-located in the PCM-based devices. These computers have better computing speeds but, use far less energy.

Researchers at the University of Cambridge, the Singapore A*STAR Data-Storage Institute and the Singapore University of Technology and Design, worked on the current design. The team used a type of PCM that was based on a chalcogenide glass. The material can be melted and recrystallized in about half a nanosecond (billionth of a second).

PCMs have been around since 1960s. These materials were earlier used in optical-memory devices, such as re-writeable DVDs. Now, PCMs are used in electronic memory applications. Some of the major limitations of the material is that they are unstable in their starting amorphous phase and do not perform calculations as fast as silicon-based devices.

The team at Cambridge found that performing the logic operations in reverse - begining from crystalline phase and then switching to the glassy phase - makes the material much more stable and work faster.

Information is shuffled around in traditional computers, which costs both time and energy.

"Ideally, we'd like information to be both generated and stored in the same place," said Dr Desmond Loke of the Singapore University of Technology and Design, the paper's lead author, according to a news release. "Silicon is transient: the information is generated, passes through and has to be stored somewhere else. But using PCM logic devices, the information stays in the place where it is generated."

The study is published in the journal Proceedings of the National Academy of Sciences.