On Some Modern Uses of the Electron in Logic and Memory

The electron plays a role in many facets of modern life—lighting, heating, welding and so on. Here, I concentrate on the use of electrons primarily in logic and memory. I generally skip the early history—that of electronic tubes—and start instead with the modern integrated circuit and then go on to explore possible alternatives to the now‐dominant silicon MOSFET technology. (MOSFET stands for metal oxide semiconductor field‐effect transistor.) This approach is enforced not only by space considerations, but also by the fact that the passing years have erased triodes, power pentodes, klystrons, traveling‐wave tubes and the like from my memory. Not that they are no longer used; clones of the 6L6, EL34 and KT88 are still used in some of the best audio amplifiers. Microwaves and power applications still rely heavily on tubes. Cathode‐ray tubes are still the standard display, although their days may be numbered—at least at the large and small ends. Electron microscopes and lithography tools are, in a sense, large demountable vacuum tubes. (They are the subject of Murray Gibson's article on page 56 in this special issue.) However, over the past 40 years, the vacuum tube has been displaced by solid‐state devices as the basis of most computer, low‐power amplifier, communications and control circuits. (See figure 1, which shows a computer processing unit.)