Researchers Grow Ultrapure Crystals in High-Vacuum System
Scientists have long known that the fewer impurities there are in a semiconductor material, the faster electrons can travel through it. Impurities act as roadblocks, scattering and reducing their speed.
Recently a team of researchers led by Mordehai Heiblum at the Weizmann Institute of Science in Rehovot, Israel, enhanced the vacuum system used in growing gallium arsenide crystals. Gallium arsenide is used in the laser component of compact disc players.
The improved vacuum system produced crystals that were 25 percent purer, resulting in electron speeds of 14.4 cm/s. In addition, electrons traveled farther -- 120 µm -- before scattering. Over these path lengths, electrons displayed wavelike properties, rather than like particles at shorter wavelengths. A Bell Laboratories team set the previous purity record in 1989.
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