IEEE Computer Volume 11 Number 12 -- NEW APPLICATIONS & RECENT RESEARCH
Original Publication Date: 1978-Dec-01
Included in the Prior Art Database: 2005-Nov-10
Software Patent Institute
Prof. D. A. Michalopoulos: AUTHOR [+2]
NEW APPLICATIONS & RECENT RESEARCH * Faster semiconductor electron speeds may boost chip performance
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NEW APPLICATIONS & RECENT RESEARCH
Prof. D. A. Michalopoulos
California State University, Fullerton
Faster semiconductor electron speeds may boost chip performance
Scientists at Bell Telephone Lab. oratories have achieved a potentially significant advance in solid~state tech. nology by doubling the speed at which electrons can move through semiconductor crystals at room temperature.
An important factor limiting semicom ductor conductivity is the tendency of their electrons -- charged negatively -- to be slowed down by the positively and negatively charged "impurities" added to semiconducting materials. Such impurities are implanted in a precisely controHed fashion to act as a source of free electrons. Bell Labs researchers have devised a new technique to isolate the electrons from their source impurities, so they can move quickly and with little interference.
The speed of semiconductor devices is usually improved by physical designs that reduce the distances electrons need to travel. By boosting electron speed, however, this latest advance has opened up a new approach to enhancing device performance. It extends the limits of a basic property (the material's electrical conductivity) that has until now been considered a constant.
The new technique is an extension of the usual "doping" method used to add the small amounts of an element needed to act as "donor" impurities. In the case of the semiconductor gallium arsenide, or GaAs, the donor impurity is often silicon. Each silicon atom gives up one of its electrons, which moves through the semiconductor as current. The silicon left behind, having lost an electron, is positively charged. As moving electrons pass silicon impurities, however, they are slowed by their attract tion to the now positively charged atom. They may even recombine with the silicon atom and stop moving altogether.
To isolate these electrons from the donor atoms, the researchers layered two semiconductor materials to form a single crystal. This...