Glass Semiconductors Developed
January 1969 Radio-Electronics

January 1969 Radio-Electronics [Table of Contents] Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Electronics, published 1930-1988. All copyrights hereby acknowledged.

The term "ovonic" - a fairly unfamiliar word these days - appeared in the May edition of Radio-Electronics, in an article titled, "All About Ovonics," just a few months after this news item ran in the January issue (which I posted last month). Ovonics is a portmanteau of "Ovshinsky" (from Stanford R. Ovshinsky, the inventor) and "electronics." Read the "All About Ovonics" article for a deeper dive into the subject. The big deal, which turned out to be not a big enough deal, was the use of amorphous (strangely spelled "amphorous") glassy compounds as semiconductors rather than the standard crystalline silicon structures. Maybe someday an enterprising genius inventor type will give a rebirth to the concept.

Glass Semiconductors Developed

A solid-state physics development involving the switching characteristics of glassy amorphous semiconductors may eventually bring about a size and price cut in some semiconductors.

Compounds such as oxide- and boron-based glasses and materials that contain tellurium and chemically similar elements can be made to act electrically like diodes and magnetic memory cores. Unlike the orderly crystalline structure of semiconductors that require complex and expensive doping, the glassy materials have a disordered (amorphous) atomic structure.

Two new switching devices using the materials have been developed and are being manufactured by Energy Conversion Devices, a Michigan firm. Called the Ovonic Threshold Switch (OTS) and Ovonic Memory Switch (OMS) by the developer and company president, Stanford R. Ovshinsky, the devices can switch both alternating current and direct current equally well. Ordinary semiconductor pn-type junctions have a preferred current direction.

Developer of the new devices, Stanford R. Ovshinsky, demonstrates the conducting state (right) and non-conducting (disordered) state of polymer structures.

When voltage is applied to an CTS, it remains an insulator until a threshold voltage is reached. It then switches rapidly (150 trillionths of a second) into conduction and conducts as long as current exceeds a critical value. Depending on its thickness and composition, threshold voltage may range from about two to several hundred volts. The OMS is similar, except it remains in its conduction state when current is removed, and blocks current when a pulse is again applied.

The firm foresees a number of "spectaculars" for the devices, such as flat TV displays and pocket-size computers. The devices can be produced cheaply in sizes as small as 0.005 of an inch across.