Purdue News

November 19, 1986 Tiny Memory Cell Measures Up To New Supercomputer Technology West Lafayette, Ind. – A tiny memory cell developed at Purdue University may stack up as one of the most promising new developments toward building a generation of faster, more powerful computers. The new cell, made of gallium arsenide--a superfast semiconductor that holds promise for high-speed computers of the future--is six times smaller than existing gallium arsenide cells, and will allow designers to stack hundreds of thousands of storage units on each microchip, says James A. Cooper, professor of electrical engineering at Purdue and one of the primary investigators for the project. "High-speed computers require lots of high-speed memory. Our cell will provide systems designers with the high-storage capabilities needed for future gallium arsenide supercomputers," says Cooper. "Because of its size, designers can use up to six times as many memory cells in a given area," he adds. A technical report on the new storage device is presented in the November issue of Electron Device Letters. The paper represents the first reported work in "dynamic" random-access memories developed for gallium arsenide computers. To date, the only memory elements available to gallium arsenide systems designers have been six-transistor static cells, which require considerable chip area and continuously consume power, says Cooper. The Purdue memory cell uses only one transistor to provide the same flexible, read-write memory capabilities offered by its larger predecessors, and operates on an on-off basis that allows the element to use power only when needed. During the last few years, researchers around the world have focused attention on gallium arsenide and related materials to build a new generation of supercomputers. The new machines will be up to l00 times more powerful than today's supercomputers, says Michael Melloch, professor of electrical engineering who worked with Cooper on the project. "Gallium arsenide is an ideal material for building computers. Its properties make it possible to process information at speeds significantly higher than the silicon components used in existing computers, and it can operate at very low energies so little heat is generated by the system," he explains. Gallium arsenide is also optically active, so information can be transmitted between chips using light instead of wire, adds Melloch. "Most of our future computer and communication systems will rely on optics to transmit information." Though it will be many years before gallium-arsenide technology reaches consumer products for the home, the technology offers the promise of developing faster computers and more efficient communication systems within the next five years, says Melloch. The new memory cell was developed at Purdue using a molecular beam expitaxy system--a technique that allows researchers to grow single crystals of a substance from two or more chemicals, such as gallium and arsenic. When kept at very low temperatures--minus 320 degrees Fahrenheit--the dynamic memory cell is capable of storing information without renewal for up to nine days--a very long period of time for computer memory, says Melloch. "These materials require extremely low temperatures for optimal performance," he says. "We are now working to develop similar memory cells for use at room temperature." The Purdue team has received a patent for the new device. The project is funded by the National Science Foundation and Purdue. Funding for the Optoelectronics Laboratory at Purdue, where much of the work is done, is provided by the Indiana Corporation for Science and Technology. Purdue News Service: (765) 494-2096; purduenews@purdue.edu To the Purdue News and Photos Page