Computer Memory Improvements with Nanotechnology

Hard drives used as memory in computers  consume more power and have more chance of failure than solid state memory that doesn't have any moving parts.

For that reason, solid-state computer memory has become popular on smaller computers, such as tablets. This solid-state computer memory take up less space, uses less battery power,  and is less likely to be damaged if the device is dropped. Nanotechnology is being used to improve the density of solid-state computer memory.

Computer memory: Applications under Development

Solid-state drives store information on a type of transistor called flash. Currently, flash memory manufacturers use nanolithography techniques to build memory chips with minimum feature sizes as small as 20 nm.

Researchers have demonstrated vertical flash transistors. The idea is that by making the transistors vertically memory cells could be stacked on top of each other, with the potential for increasing the memory density. Researchers suggest that the memory cell density could be 8 to 16 times higher than for planar transistors.

Hewett Packard is developing a memory device that uses nanowires coated with titanium dioxide. One group of these nanowires is deposited parallel to another group. When a perpendicular nanowire is laid over a group of parallel wires, at each intersection a device called a memristor is formed.

A memristor can be used as a single-component memory cell in an integrated circuit. By reducing the diameter of the nanowires, researchers believe memristor memory chips can achieve higher memory density than flash memory chips. HP is working with Hynix Semiconductor to develop memory components based upon memristors, called Resistive Random Access Memory (ReRAM)

Magnetic nanowires made of an alloy of iron and nickel are being used to create dense memory devices. Researchers at IBM have developed a method to magnetize sections of these nanowires. By applying a current they can move the magnetized sections along the length of the wire. As the magnetized sections move along the wire, the data is read by a stationary sensor. This method is called race track memory because the data races by the stationary sensor. The plan is to grow hundreds of millions of U-shaped race track nanowires on a silicon substrate to create low-cost, high-density, and highly reliable memory chips.

Another method of using nanowires is being investigated at Rice University. Researchers at Rice have found that they can use silicon dioxide nanowires to create memory devices. The nanowire is sandwiched between two electrodes. By applying a voltage, you change the resistance of the nanowire at that location. Each location where the nanowire sits between two electrodes becomes a memory cell.

The key to this approach is that researchers have found that they can repeatedly change the state of each memory cell between conductive and nonconductive without damaging the material’s characteristics. These researchers believe that they can achieve high memory densities by using nanowires with a diameter of about 5 nm and by stacking multiple layers of arrays of these nanowires like a triple-decker club sandwich.

An alternative method being developed to increase the density of memory devices is to store information on magnetic nanoparticles. Researchers at North Carolina State University are growing arrays of magnetic nanoparticles, called nanodots, which are about 6 nm in diameter. Each dot would contain information determined by whether or not they are magnetized. Using billions of these 6-nm diameter dots in a memory device could increase memory density.

Computer Memory: Company Directory

Company	Products or Projects
Everspin Technologies	Magnetoresistive Random Access Memory (MRAM)
HP	Memristor
IBM	Nanophotonics
Intel	Integrated circuits with nano-sized features