INDUSTRY NEWS

Run pure, run free

By improving the vacuum system they use to grow GaAs crystals, a team of researchers in Israel has freed the electron to travel faster. The system created by scientists at the Weizmann Institute of Science in Rehovot has let them reduce the number of contaminants in GaAs samples. The cleaner samples have fewer impurities that can scatter electrons and impede their speed in next-generation ICs.

The purity improvement is "more of a technological feat than a scientific breakthrough," the institute's Mordehai Heiblum told Science News. The GaAs crystals are about 25% purer than any previously grown. Heiblum's team recorded a maximum electron speed of 14.4 million cm/sec on samples of multiple alternating layers of GaAs and aluminum GaAs.

The researchers recorded the electrons' travel at one-tenth of a degree above absolute zero. The impurities have little effect on the flow of electrons in real devices, which operate at room temperature. The real impact comes as device sizes shrink.

The ultrapure crystals allowed the team to study how electrons travel in material "at their quantum mechanical limit." In the GaAs crystals, the negatively charged particles travel 120 µm before scattering. At those long distances, the electrons show wavelike properties. Traveling shorter distances before scattering, they behave like particles.

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