The maximum RAM in a desktop computer amounts to a few gigabytes. When it comes to storage, the mark rises to a few terabytes at best. That is an impressive amount of information; however, demand continues to grow. Fortunately, several companies are developing a long-term solution, applying a new super-dense memory based on a resistive design, which reminds us of memristors.
The most advanced smartphones on the market can offer two or three gigabytes of RAM. Needless to say, that places them on par with any computer, laptop or desktop. But we know deep down that it is not enough. Perhaps it is enough now, but within a few years mobile devices will need to gain speed and storage density. The same happens with computers, and the feeling is that current technologies are stagnant. Luckily, there are developments with gigantic potential.
A Prototype with Impressive Density
In 2013, a company based in California called Crossbar presented a resistive memory prototype with such high density that it could store up to a terabyte of data on an area equivalent to a postage stamp.
The problem with this resistive memory is that it has a very complicated manufacturing process, which involves high voltages and environments with very high temperatures. The key to boosting the adoption of this technology is to simplify production lines.
The Rice University Approach
This brings us to work presented by Rice University in July 2014. There, they explain that everything begins with a layer of silicon oxide full of holes, each five nanometers in diameter. This porous layer is enclosed between two other layers that act as electrodes. When electricity is applied, the metal of these outer layers, usually gold or platinum, penetrates the holes in the silicon oxide, establishing an electrical connection between the two electrodes. With the application of more electricity, a crack is created in the metal inside the pores, giving rise to a nanometric gap of silicon. The storage of bits is carried out by altering the conductivity of that silicon with low-voltage electrical pulses, and that state is preserved until another pulse rewrites it.
This new resistive memory requires much lower voltages in its fabrication, and its density is higher (nine bits per cell). There is also the possibility of stacking memory layers, something in which companies like Samsung are already working. With the new memory, it would be possible to create modules with hundreds of layers, accumulating entire terabytes of capacity, in a volume small enough to fit inside smartphones and tablets.
So far, it is the same people from Crossbar that seem best positioned to launch resistive memories to the market. In fact, the first units would be seen during this year, although the '3D version' with multiple layers will demand two or three more years.
Rice University
