Офіційне художнє зображення процесу аморфизації під впливом електричного струму / Akanksha Jain
Phase change in phase-change memory PCM was accidentally triggered not by heating, but by a steady current, which means much less consumption and a plethora of technical prospects.
Scientists may have accidentally overcome a major hurdle for the deployment of next-generation data storage technologies. Using a material called indium selenide (In2Se3), researchers discovered the possibility of reducing the energy needs of phase-change memory PCM (capable of storing data without constant power) — by up to 1 billion times.
The discovery is an important step towards creating so-called universal memory, which combines the properties of RAM and data storage devices. RAM is fast but takes up a lot of space and requires a constant power source to operate. Solid-state drives are much denser and can store data when computers are turned off. Universal memory combines their best features.
PCM works by switching materials between two states: crystalline, where atoms are neatly organized, and amorphous, where atoms are arranged randomly. This encodes values 1 and 0 by changing the state of the matter. However, the technology used for this involves heating and rapidly cooling materials and requires a lot of energy.
Researchers found a way to completely bypass the melt-quenching process, instead causing amorphization through an electrical discharge. This drastically reduces the energy needs of PCM and opens up prospects for expanded commercial application.
The discovery is based on the unique properties of indium selenide, a semiconductor material with both ferroelectric and piezoelectric characteristics. Ferroelectric materials can spontaneously polarize, meaning they can generate an internal electric field without needing an external charge. Piezoelectric materials physically deform when subjected to an electric charge. Testing the material, researchers noticed that its regions became amorphous when subjected to a continuous current. Moreover, this happened completely by accident.
“I actually thought I might have damaged the wires. Normally you would need electrical pulses to cause any amorphization. Suddenly, the continuous current disrupted the crystalline structure, which shouldn’t have happened,” said Gaurav Modi, a doctoral student in materials science and engineering at Penn Engineering.
Further analysis revealed a chain reaction caused by the semiconductor’s properties. It starts with tiny deformations in the material, caused by the current, which triggers an “acoustic jerk” — a sound wave similar to seismic activity during an earthquake. It travels through the material, creating amorphization in micrometric areas in a process researchers compared to an accelerating avalanche.
The scientists explain that the properties of indium selenide, including its dual ferroelectric and piezoelectric structure, work together to provide a path for amorphization with an ultra-low level of energy, triggered by impacts. This could lay the foundation for future research into new materials and devices for low-power electronic and photonic devices. The research is published in Nature.
Source: LiveScience