Storage in today's computers is based on rotating magnetic platters or flash memory. Both of these mediums work well, provide large amounts of storage and have been around for a while now. Some scientists don’t believe that flash is the future for storage in computers and electronic devices. In fact, the future of storage could be based on something kids use every day at school -- pencil lead or graphite.
A team of researchers at Rice University has found a method of creating a new type of memory from a strip of graphite only 10 atoms thick. Graphite is the basic element in the new type of memory. The scientists describe in a paper published in the online journal Nature Materials a storage device that utilizes the conducting properties of graphene. A large clump of graphene is better known as graphite, something school kids doodle with everyday.
Rice professor James Tour says that graphene memory would increase the amount of storage in a two-dimensional array by about five times. He says that this massive improvement is due to the individual bits being able to be made smaller than 10 nanometers. By comparison, circuitry in your average flash memory chip today is 45nm. Another big benefit of graphene memory is that switches can be controlled by two terminals rather than the three terminals used in flash memory today.
The two-terminal capability is important because it provides the capability to make three-dimensional memory practical since the very thin graphene arrays can be stacked, multiplying the storage capacity of the array with each graphene layer.
Storage arrays using graphene will be mechanical devices at their core and as such, the chips will consume very little power. Much lost power in flash storage comes from leakage; graphene memory will need little power leading to less leakage while keeping data intact. Graphene memory has a massive improvement in on-off power ratio compared to current memory technologies.
Tour said in a statement, "It’s (power savings) huge — a million-to-one. Phase change memory, the other thing the industry is considering, runs at 10-to-1. That means the ‘off’ state holds, say, one-tenth the amount of electrical current than the ‘on’ state."
Tour explains that current tends to leak from an off that is holding a charge. He says, "That means in a 10-by-10 grid, 10 ‘offs’ would leak enough to look like they were ‘on.’ With our method, it would take a million ‘offs’ in a line to look like ‘on'. So this is big. It allows us to make a much larger array.”
Another benefit of graphene as a storage medium is that while it puts off little heat, it is able to operate in a very wide temperature range. The researchers have tested the system to minus 75 to over 200 degrees Celsius.
Performance of graphene-based systems is impressive, the researchers say that the new switches are faster than the lab's testing equipment can measure and they promise long life as well. "We’ve tested it in the lab 20,000 times with no degradation,” said Tour. “Its lifetime is going to be huge, much better than flash memory."
The processes uses graphene deposited on silicon via chemical vapor deposition making for easy construction that can be done in commercial volumes with methods already available says Tour.
quote: Lastly can the sense amplifier go to such high ratios (10^7); it looks like a signal-to-noise challenge.