The improvements in the device characteristics of n-channel MOSFET's that occur at low temperatures are considered in this paper. The device parameters for polysilicon gate FET's with channel lengths of the order of 1 µm have been studied both experimentally and theoretically at temperatures ranging from room temperature down to liquid nitrogen temperature. Excellent agreement was found between the experimental dc device characteristics and those predicted by a two-dimensional current transport model, indicating that device behavior is well understood and predictable over this entire temperature range. A device design is presented for an enhancement mode FET with a channel length of 1 µm that is suitable for operation at liquid nitrogen temperature. Copyright © 1977 by the Institute of Electrical and Electronics Engineers, Inc.