Breakthrough flash device could boost computing with faster, efficient chips

A research team from Fudan University in Shanghai has developed a groundbreaking two-dimensional single-electron quantum flash memory device that could dramatically improve the speed and energy efficiency of future computing systems.

The study, published in the journal Science on July 17, marks a major milestone in memory technology. Compared with existing memory technologies such as Dynamic Random Access Memory, or DRAM, and 3D NAND flash memory, the new device combines three qualities that have long been difficult to achieve at the same time: high speed, low power consumption and the ability to retain data without a power supply.

The researchers said the technology could help meet the growing computing demands of artificial general intelligence, or AGI, which requires much faster and more efficient ways to process and store massive amounts of data.

Memory chips are a key component of modern computers because they store and retrieve data needed for processing. However, the speed at which data can be accessed and the amount of energy required remain major obstacles to improving computing performance.

Today's mainstream memory technologies each have strengths and weaknesses. DRAM can read and write data very quickly, making it suitable for high-performance computing, but it loses all stored information once power is turned off. In contrast, 3D NAND flash memory can preserve data for years without electricity, but it is slower when reading and writing information.

To overcome these limitations, researchers from Fudan University's State Key Laboratory of Integrated Chips and Systems and the College of Integrated Circuits and Micro-Nano Electronics have spent more than a decade developing a new type of memory.

Last year, the team introduced its PoX 2D flash memory prototype in the journal Nature in April and unveiled the world's first full-featured 2D flash memory chip, CY-01, in the same journal in October.

After developing what they described as the fastest semiconductor charge-storage technology to date, the researchers turned to an even more ambitious goal: storing one bit of information using just a single electron.

Electrons are the tiny particles that carry electric charge and form the basis of electronic devices. In theory, using a single electron to represent one bit of information would enable the smallest and most energy-efficient memory possible.

However, scientists have long believed that such technology would be extremely difficult to achieve because the behavior of individual electrons is governed by quantum mechanics and is difficult to observe under normal conditions.

Starting from the basic principles of quantum mechanics, the Fudan team developed a new quantum flash technology that allows a single electron to be precisely controlled and stored. By taking advantage of the atomic-scale properties of two-dimensional semiconductor materials, the researchers designed a new device structure that enabled them to reliably manipulate individual electrons.

For the first time, the team directly observed the stable, nonvolatile storage of a single electron at room temperature of 27 C. Previously, many researchers believed such quantum behavior could only be observed at extremely low temperatures.

The researchers also developed a device with what they describe as the world's largest nonvolatile quantum memory window. The device requires only one electron to produce a memory window of 0.5 volts, demonstrating the possibility of storing one bit of information with a single electron.

The breakthrough points to the potential for much denser memory chips that consume far less power while delivering faster performance, making them well suited for future AI systems.

"Our demands for storage speed, capacity, energy efficiency and stability have reached a new level in the AI era," said Liu Chunsen, a first author and corresponding author of the paper.

"Being able to store one bit of information by changing the state of a single electron will significantly reduce power consumption and pave the way for much larger storage capacity," he said.

Zhou Peng, another corresponding author and one of the project's lead researchers, said today's advanced DRAM technology typically requires about 200,000 electrons to store a single bit of information.

In contrast, the team's new device uses only one electron to store the same amount of data while maintaining nonvolatile storage.

"This greatly improves storage efficiency while reducing power consumption and creating the potential for much higher storage density," Zhou said.

Liu added that the new memory could also be integrated directly with processors, allowing data to move much more quickly between computing and storage units.

"That would significantly reduce data transfer delays, improve computing efficiency and help expand AI applications across industries," he said.

During the research, the team also made a new scientific discovery. For the first time, the researchers predicted and experimentally observed a previously unknown quantum memory effect, in which a quantum state can be sharply controlled through a mechanism they describe as a "density of states scissors".

According to the team, the discovery provides a new theoretical foundation for single-electron quantum memory and could accelerate the engineering and commercialization of quantum storage technologies in the future.