The charge transfer and retention characteristics of MNOS structures have been studied as a function of specified processing parameters utilized when fabricating the tunneling silicon oxide and charge storage silicon nitride layers. A grid array of n+ junctions fabricated on 2 ohm-cm "p" type silicon substrates allowed simulation of the transient characteristics of FET's. Electrical measurements included switching speed, static and dynamic charge storage windows, and stored charge retention with time. The switching speed and window width were influenced by some processing parameters. Some shortcomings with recent discharge models are noted, based upon the data obtained. Limited (multiple cycling) "fatigue" studies have indicated improved window behavior with increased write-erase voltages, and pulse widths below one microsecond, for MNOS structures with the tunneling oxide prepared within an NO plus H2 ambient. © 1975 American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.