RESEARCH TRIANGLE PARK, N.C. -- A new Army-funded memory device, like a USB stick or hard drive, promises to increase data upload speed, greatly extend smart phone battery life and reduce data corruption.
The research, funded by the Army Research Office, an element of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory, and conducted at University of Southern California, improves the material and structure of memory devices with groundbreaking results.
Researchers published findings in Nature Electronics describing the new device, which combines new van der Waals materials with an innovative device design for the memory concept called the ferroelectric tunneling junction.
Van der Waals materials have strong in-plane covalent bonding and weak interlayer interactions. Ferroelectric materials have a spontaneous electric polarization that can be reversed by the application of an external electric field.
“This breakthrough will have significant impact on future electronics for the U.S. Army, enabling man-portable electronic systems with improved size, weight and power,” said Dr. Joe Qiu, ARO program manager for solid-state electronics and electromagnetics.
This new memory device is part of a family known as non-volatile memory devices, meaning they can be unplugged and still retain their data, much like USB flash drives. As the ferroelectric polarization field in these materials reverses direction, it can either facilitate the current flow, corresponding to an on setting, or block the current flow, corresponding to an off setting. These on and off settings can represent the 1 and 0 of digital information. Alternating between an on and off state is how the device records the series of ones and zeros needed to capture data.
Traditionally, these structures came in two primary forms: The most basic form uses metals as contacts on both sides of the junction, while a more recent structure replaces one of the metal contacts with a semiconductor material. The new device, using asymmetric metal and semimetallic graphene contacts, is able to exceed the performance of all previously demonstrated ferroelectric tunneling junctions while offering promising prospects for integration with silicon electronics.
“This van der Waals FTJ offers high ratio between the on and off states, also known as the tunneling electroresistance, that overcomes a critical challenge in building high performance FTJ memory,” said Han Wang, associate professor of electrical and computer engineering at the USC Viterbi School of Engineering.
More simply put, the unique properties of the new device, combined with a novel design structure, makes it much easier to distinguish between the different data states. The better that can be done, the more reliably and efficiently data can be stored and processed. Furthermore, the unique advantage offered by van der Waals ferroelectric material to approach atomic scale thickness can eventually lead to much faster and energy efficient ferroelectric tunneling junction memory.
The researchers hope that with time, their device can be scaled up and may become a replacement not just for existing non-volatile memory, but also volatile memory (devices requiring constant power to retain memory like D-RAM storage devices) commonly found in computers.
With its robust endurance and ability for multi-bit operation, the technology also has promising potential for applications in in-memory computing and other emerging energy-efficient computing schemes.
In addition to the Army funding, the National Science Foundation partially funded this research.
CCDC Army Research Laboratory is an element of the U.S. Army Combat Capabilities Development Command. As the Army’s corporate research laboratory, ARL discovers, innovates and transitions science and technology to ensure dominant strategic land power. Through collaboration across the command’s core technical competencies, CCDC leads in the discovery, development and delivery of the technology-based capabilities required to make Soldiers more lethal to win the nation’s wars and come home safely. CCDC is a major subordinate command of the U.S. Army Futures Command.