Micrometer-dimension n-channel silicon-gate MOSFET's optimized for high-performance logic applications have been designed and characterized for both room-temperature and liquid-nitrogen-tem-perature operation. Appropriate choices of design parameters are shown to give proper device thresholds which are reasonably independent of channel length and width. Depletion-type devices are characterized at room temperature for load device use. Logic performance capability is demonstrated by test results on NOR circuits for representative fanout and loading conditions. Unloaded ring oscillators achieved switching delays down to 240 Ps at room temperature and down to 100 Ps at liquid nitrogen temperature. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.