Wiring imperfect crystals.Wiring imperfect crystals Thin metal strands, only a few atoms thick, can be deposited within silicon wafers to create an extremely fine wiring network, say researchers at Ohio State University Ohio State University, main campus at Columbus; land-grant and state supported; coeducational; chartered 1870, opened 1873 as Ohio Agricultural and Mechanical College, renamed 1878. There are also campuses at Lima, Mansfield, Marion, and Newark. in Columbus. The key step involves bonding copper to tiny imperfections deliberately introduced into silicon crystals. Metallurgical met·al·lur·gy n. 1. The science that deals with procedures used in extracting metals from their ores, purifying and alloying metals, and creating useful objects from metals. 2. engineer William Clark and his colleagues start the process by welding welding, process for joining separate pieces of metal in a continuous metallic bond. Cold-pressure welding is accomplished by the application of high pressure at room temperature; forge welding (forging) is done by means of hammering, with the addition of heat. together two thin slices of crystalline Like a crystal. It implies a uniform structure of molecules in all dimensions. For example, phase change technology, widely used for rewritable optical discs, uses crystalline spots (bits) to reflect the laser beam. Amorphous, non-crystalline bits do not reflect light. silicon. If the evenly spaced rows of atoms in the two slices are aligned precisely, then the crystals bond perfectly and the boundary disappears. But if the slices are even slightly misaligned mis·a·ligned adj. Incorrectly aligned. mis  a·lign ment n. , a grid of dislocations is formed at the boundary. Clark and his team then coat the misaligned crystal sandwich's surface with a layer of copper. Heating the coated sandwich allows copper atoms to diffuse into the crystal's interior. The atoms tend to settle in the dislocations, creating a web of metal filaments. Wires this small may have all sorts of unusual properties. "There is evidence for some rather strange diode behavior in arrays like this," says Clark. "It does funny things that you wouldn't expect." Yet unsolved is the problem of connecting such arrays to an electric circuit so that they can be used, perhaps for storing information. |
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