With today's increasing use of high-definition content in consumer electronics devices, there is an ever-growing demand for fast performing compact products with high storage capacity. Manufacturers of storage systems are under pressure to find novel techniques to squeeze more and more data bits per inch to provide both cost-efficient and high-capacity devices. The two technologies discussed here mark significant breakthroughs in material science, and according to their inventors could revolutionize storage.
Scientists at the University of California, Berkeley, and the University of Massachusetts Amherst have jointly developed an easily executable technique whereby nanoscale elements can accurately assemble themselves over sizeable surfaces. According to the researchers, the new method could inadvertently change the face of data storage capacity for electronic media. In fact, the team claims that in the future, it would be possible to store the equivalent of 250 DVDs on a device the size of a small coin.
Ting Xu, assistant professor in the department of materials science and engineering at UC-Berkeley, explains that by using a thin film of block copolymers – two or more chemically dissimilar polymer chains linked collectively – the molecules in the material were shown to assemble themselves into an exceptionally accurate, equidistant pattern when distributed on a surface. Before this, scientists had found it difficult to achieve results at such precision for semiconductor purposes because the strictly assembled molecules weren't able to preserve their accurate positions as the surface increased in size.
The strength of the formation is essential because once it fails, the domains can neither be read nor written to, rendering the device useless for data storage.
“I expect that the new method we developed will transform the microelectronic and storage industries and open up vistas for entirely new applications,” says Thomas Russell, an expert on the behavior of polymers and co-lead investigator on the project from UMass Amherst.
To overcome the obstacles related to the material surface area, the team layered the film of block copolymers onto the surface of a commercially available sapphire crystal. The crystal was then cut at an angle and heated to temperatures ranging from 1,300 to 1,500 degrees Celsius (2,372 to 2,732 degrees Fahrenheit) for 24 hours. At this point, its surface was shown to reorganize itself into a very sequential model of saw-tooth ridges that can be subsequently utilized to direct the self-assembly of block polymers.
The new method allowed the researchers to achieve defect-free arrays of nanoscopic elements as small as 3 nanometers wide, leading to densities of 10 terabits per square inch –1,250 gigabytes. To add to the flexibility, the angle and depth of the saw tooth ridges can be adjusted by varying the temperature at which the crystal is heated to polish up the required pattern.
“We can generate nearly perfect arrays over macroscopic surfaces where the density is over 15 times higher than anything achieved before,” Russell says. “With that order of density, one could get a high-definition picture on a screen the size of a JumboTron.”
While this technology could significantly advance our abilities when it comes to storage densities, another technology from the National Institute of Standards and Technology brings semiconductor materials into the picture by enabling these to store data.
NIST scientists have demonstrated for the first time the concept of a vital magnetic characteristic of specifically fabricated semiconductor devices. The team hopes that this breakthrough could lead to smaller and faster devices, benefiting from the magnetic data storage capabilities found in the semiconductor materials.
Conventional magnetic storage devices used in consumer electronics, such as computer hard drives, MP3 players and other products based on metallic materials, have separate data storage and execution units. At least part of the delay (or slowness) generated by current products is because of the relatively long route the data traverses – being retrieved from the storage, passed on to the CPU for processing and execution, and then back again to the storage unit. These back-and-forth transfers dramatically hinder the general performance of the system.
The new technology developed by NIST in collaboration with Korea University and the University of Notre Dame, has proved that thin magnetic layers of semiconductor material could demonstrate antiferromagnetic (AF) coupling, in which one layer spontaneously lines up its magnetic pole in the opposite direction to that of the adjacent magnetic layer.
The 2007 Nobel Prize in physics was granted for the discovery of AF coupling in metals. Researchers say their new technology enables this property to be extended from metals to semiconductor materials. As a result, the new semiconductor materials would not only compute but also be able to store data.
The researchers reported that at low temperatures and high magnetic fields, the beamed neutrons data was observed to indicate a parallel alignment of all layers. This, they say, shows that AF coupling is achievable in GaMnAs-based multilayers.
Of course, the technique has yet to become practical, as this phenomenon occurs only at very cold temperatures nearing 30 Kelvin (-243.15 Celsius or -405.67 Fahrenheit). However, the researchers say they expect that a method for maintaining the same magnetic properties at room temperature can be developed.
Once commercialized, the potential advances in storage systems are likely to have dramatic consequences on the consumer electronics market. While both technologies are yet in relatively early stages of development, if the scientists do succeed in demonstrating easy-to-implement solutions based on the experimental findings, the emerged solutions could answer the industry's demands on both the cost and performance levels.