Not-so-dotty material

US researchers have coaxed the metal nickel to self-assemble into arrays of nanodots, with each dot a mere seven nanometres across.

Jagdish Narayan and Ashutosh Tiwari, both of North Carolina State University and the National Science Foundation’s Center for Advanced Materials and Smart Structures, invented the new material and developed the manufacturing processes to make it.

Presently, the researchers are working with an industry partner to apply the technique to development of next-generation light-emitting diodes (LEDs). The experimental LEDs are already more efficient than existing devices, potentially lasting decades and using a fraction of the power of fluorescent bulbs.

Narayan and Tiwari used a pulsed excimer laser to create conditions under which nickel self-assembles into 3-D, ordered arrays within aluminum oxide and titanium nitride matrices. Applying similar techniques to gallium nitride and zinc oxide, the researchers are hoping to further improve the efficiency of their LED devices.

‘In the past we could make only one-layer structures and 3-D self-assembly wasn’t possible. We couldn’t control the medium. Now, with this development we can control the medium and do 3-D self-organisation. More importantly we can change the size in different layers and can change the functionality at different depths,’ says Narayan.

Because the manufacturing method they have developed works with a variety of materials and may drastically reduce imperfections, the new procedure may also bolster research into extremely hard materials and efforts to develop ultra-dense computer memory.

But computer applications are further away, as many additional hurdles need to be cleared before the nanodots become actual chips. However, since every nickel-metal nanodot could theoretically store a single bit of information, the researchers believe that a one-inch chip using that technology could eventually store 10 Terabits of data.

Further details maybe found in the September, 2004 issue of Nanoscience and Nanotechnology.