Sapphires and rubies may edge out silicon if University of Delaware engineers can sweat the details.
The engineers are busily perfecting a technique they developed to produce ultra-thin alumina films. Alumina, found in its mineral form in sapphires or rubies, can offer electrical storage capacity three times greater than today's transistors, which are made from silicon dioxide.
The technique involves combining aluminum with positively charged silicon substrate in the presence of nitrogen and argon gases. This process creates aluminum nitride, which is then oxidized. Through oxidation, the nitrogen gets replaced with oxygen to form aluminum oxide, or alumina.
The alumina is then placed into a cylindrical furnace and heated so it will thicken. The higher the temperature, the thicker the film. For example, heating a sample for one hour at 1,475°F produces alumina films with a thickness of 33 nanometers. Heating a sample at 1,832°F for the same period yields a film with a thickness of 524 nanometers.
The ability to generate thicker films can potentially fix a growing problem with silicon-based transistors: As semiconducting circuits become smaller, the silicon dioxide layers become thinner. If these films become too thin, they can fail, said James Kolodzey, a professor of electrical engineering for the University of Delaware.
Because the alumina has a capacity three times that of silicon dioxide, it may be possible to make them three times thicker, Kolodzey said.
