A US research team has developed phase-change memory that could extend battery life significantly
The move to mobility has created a demand for battery longevity and this is reflected in research into memory storage at Illinois University. The Computer Engineering Department has developed a radical memory technology that uses 100 times less power than current chips.
Instead of storing bits and bytes as electrical charge, the research team has used variable resistance of materials as the basis of its memory. As with many of the low-power technologies that are emerging, the Illinois team has been working at the nanoscale level to achieve its aims.
Battery life of weeks or months
Professor Eric Pop, the team leader, said, “I think anyone who is dealing with a lot of chargers and plugging things in every night can relate to wanting a cell phone or laptop whose batteries can last for weeks or months.”
To achieve this dream, the researchers created “bits” by placing a small amount of phase-change material (PCM) in a nanoscale gap formed in the middle of a carbon nanotube. The resistance of the PCM is changed when a current is applied, switching the material from crystalline to amorphous (non-crystalline) state or back again, providing the “on/off” states that equate to zeros and ones in binary code. Once the phase is altered, it remains changed until a current is applied again.
The nanotubes act as “wires” to carry the current but they are 10,000 times thinner than a human hair. Creating nanogaps in these filaments for the PCM to be inserted, creates a minute storage system that requires half the switching current of similar PCM technologies currently in use – and 100 times less than conventionally wired electronics.
The PCM film is protected by a layer of silica (SiO2) to prolong the switching life of the device.
No power wastage
A major advantage of the circuitry built from these PCM bits is that they are not affected by magnets or scanners. In a smartphone, there is no battery power wasted in processes such as the maintenance of charge in conventional memory.
“Anytime you’re running an app, or storing MP3s, or streaming videos, it’s draining the battery,” said Albert Liao, a member of Pop’s team. “The memory and the processor are working hard retrieving data. As people use their phones to place calls less and use them for computing more, improving the data storage and retrieval operations is important.”
The research is continuing and has shown promise for further power savings. “Even though we’ve taken one technology and shown that it can be improved by a factor of 100, we have not yet reached what is physically possible. We have not even tested the limits yet. I think we could lower power by at least another factor of 10,” Pop said.