Educated Crystals

As every hi-fi addict knows, the amplifier is the part of his set that makes little angular noises into big round ones. In the parlor version, it is a dazzling assembly of vacuum tubes, resistors and capacitors. The invention of transistors twelve years ago enabled a speck of germanium to do the work of the vacuum tube, but most of the rest of the circuitry was still needed. Last week Westinghouse Electric Corp. showed an entire milliwatt amplifier, circuitry and all, contained in a single block of germanium hardly bigger (one-thousandth of a cubic inch) than the head of a pin. A 5-watt amplifier is about the size of a dime.

The one-piece amplifier is the most remarkable achievement so far in miniaturization, which has steadily reduced the size of electronic apparatus, until computers and other intricate instruments that formerly filled whole rooms are fitted into boxes no bigger than loaves of bread.

The amplifier is made by a new technique called molecular electronics. Westinghouse treats the molecules of germanium or silicon crystals in such a way that different parts of the same tiny block acquire different electrical properties. These "domains" and the "interfaces" between them act like the components of complicated electronic circuits.

The educated crystals may be microscopically small or as big as quarters, and they can do many different electronic jobs. Some are sensitive to light, and will turn on a car's headlights when the beam of a flashlight falls upon them. Others can generate alternating currents, turn them into direct currents at a different voltage. They can also serve as the electrically controlled switches that are used as thinking units in computers.

Molecular electronic units were developed under a $2,000,000 Air Force crash contract, with an eye toward their use in ballistic missiles and space rocketry. Besides being almost weightless and requiring almost no power to operate, the units promise to be much more reliable than conventional electronic circuits, because they have no internal connections to be jarred loose.

Westinghouse thinks it is only at the beginning of molecular electronics. It can grow ribbonlike crystals from pools of molten germanium, and treat them as they grow. An even more advanced technique grows "rnultizoned" crystals with their differences already in them, making them into useful electronic devices at birth.

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