Single-electron transistor. Coloured scanning electron micrograph (SEM) of a single-electron transistor. Like the larger transistors it is designed to replace, it has three parts, positive and negative terminals (lower left and right) with a gate" (centre) situated in the few nanometres between them. Altering the current on the gate alters the state of the transistor (from "on" to "off"). In a normal transistor, this requires thousands of electrons worth of charge, but this device can be activated by a single electron. This means more transistors can fit on a silicon chip, making it faster, more powerful and more efficient. Magnification unknown."