4. Electronic devices

The constant reduction in the size of electronic devices, which determines both the number of components and the speed of circuits, is encountering a number of technical difficulties in the top-down approach that are still being overcome, but beyond a lower limit, it will have to be replaced by a bottom-up approach starting from the molecular scale, based on different quantum physics principles. We will attempt to describe these two approaches in turn, illustrating them with two types of field-effect transistors: MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and SETs (Single Electron Transistors), and then briefly touch on interconnection issues.