New materials could provide high-density, energy-efficient memory storage
Thu 13 Aug 2015
By Calvin Peat
A team of scientists from Rice University have designed a new technology for solid-state memory storage, using tantalum oxide, which could potentially be a dramatic improvement on current technologies in terms of both the density of storage and the efficiency of energy consumption. The journal Nano Letters, of the American Chemical Society, has the details.
Two platinum electrodes sandwich layers consisting of multi-layer graphene, nanoporous tantalum oxide, and tantalum. The tantalum oxide loses its oxygen ions over time, turning from oxygen-rich at the top of this layer to oxygen-poor at the bottom of the layer. When all the oxygen ions are lost, it turns into pure tantalum.
The lead-author Gunuk Wang explained that, “The exchange of contact barriers causes the bipolar switching”.
In contrast to flash technology used at present, this design only requires two electrodes for each circuit, rather than three.
Rice University’s professor of materials science, nanoengineering, and computer science, James Tour, said, “This tantalum memory is based on two-terminal memory systems, so it’s all set for 3D memory stacks,” adding, “And it doesn’t even need diodes or selectors, making it one of the easiest ultradense memories to construct.”
According to the researchers, this design could store up to 162 gigabits (approximately 20GB) using crossbar array memories, and could use one hundredth of the energy required by devices currently in use. If these claims were to be realised consistently on a large, commercial scale, this would be a significant breakthrough in the field of memory storage.
Gunuk Wang cites certain obstacles such as the need to control nanopore size, and the need to make a crossbar device which is dense enough for individual bits, as concerns which will have to be addressed before the technology gets to that point.
However, while a few details still need to be ironed out, this design sounds, at least in theory, very promising.
Tantalum oxide, or strictly speaking tantalum(V)oxide, otherwise known as tantalum pentoxide, is used in capacitors in a range of electronic equipment, including computers, mobile phones, DVD players, and game consoles. It replaced aluminium oxide in this capacity, thus allowing the ‘brick’ phones of the 1980s to be replaced by smaller, lighter mobile phones.
Some may see potential ethical issues surrounding the sourcing of the rare element tantalum. One of the sources of tantalum is the mineral known as coltan, found in relative abundance in the Democratic Republic of Congo (formerly known as Zaire). While Congo represents a only small proportion of the world tantalum market, coltan mining is significant in terms the country’s economy. The coltan trade has been linked to ongoing warfare in the region, leading to tantalum being viewed as a conflict resource.
However, there’s hope for such ethical questions regarding tantalum from the Congo to be resolved. One initiative, aptly named the Solutions for Hope Project, aims to preserve the coltan mining trade’s contribution to the local economy, while ensuring that it doesn’t fund the conflict.
(In the words of Solutions Network, which the project is a part of the ‘Solutions for Hope Project‘ was launched as a pilot initiative to source conflict-free tantalum from the Democratic Republic of Congo (DRC).”)