Ultra-Fast Quantum-Dot Information Storage

Via Physorg.com -

The information-storage market is dominated by two main types: Flash memory, used in memory sticks and cell phones, and dynamic random access memory (DRAM), which is the main memory in a personal computer. Both types have their advantages and disadvantages, but a new type of memory, based on tiny atom clusters, called quantum dots, may soon displace both of them.

In research published in the March 4, 2008, online edition of Applied Physics Letters, scientists from the Technical University of Berlin, in Germany, and Istanbul University, in Turkey, describe how they created a type of quantum-dot-based memory device that can save information at speeds of only a few nanoseconds (billionths of a second).

The paper's lead author, Technical University of Berlin scientist Martin Geller, explained to PhysOrg.com, “Flash memory, which is today's market-driver in the semiconductor industry, and which everybody knows from memory sticks, digital cameras, and mp3-players, has a slow write time. The semiconductor industry is seeking faster Flash memories, but hasn't found an ultimate solution yet. Our quantum-dot-based memory may provide long storage time without power consumption of Flash memory, as wells as a fast write time and better scalability to real-life devices."

To be fair, the other established predecessor of quantum-dot memory, DRAM, does have some excellent qualities. It offers very fast information-access times—under 20 nanoseconds—and the information can be repeatedly written and rewritten on a DRAM; it has excellent so-called endurance. But a DRAM device has a big disadvantage: It is volatile, meaning the information has to be refreshed every ten milliseconds to be maintained, also resulting in a high power consumption.

"The very first prototype of our new quantum-dot-based memory scheme is already almost as fast as DRAM,” said Andreas Marent, a physicist at the Technical University of Berlin who took part in the research. “And in contrast to DRAM or Flash, the physical characteristics of quantum dots limit the write time to the picosecond, or trillionth of a second, range. That means a better device prototype should be more than 100 times faster than today's DRAM.”