Transistor size is a crucial part of improving computer technology. Smaller silicon transistors pack more computing power, making processors faster and more efficient, but silicon has its limits.
Transistors consist of three terminals, namely a drain, a source and a gate. Current flows from the source to the drain. The flow is being controlled by the gate that switches on and off depending on the voltage applied.
Because silicon allows for such a free flow of electrons, the particles get through the doors once the gate becomes too small. When this happens, the transistors leak energy.
Now, Ali Javey, from the University of California, Berkeley, and colleagues came up with an alternative to silicon transistors and made the world's smallest transistor, which has a working 1-nanometer gate. To put in perspective how small this is, the strand of a human hair is about 50,000 nanometers.
Javey and colleagues were able to do this using carbon nanotubes and molybdenum disulfide (MoS2). MoS2, an engine lubricant that can be bought in auto parts shops, belongs to a family of materials with potentials for applications in lasers, solar cells, LEDS and nanoscale transistors.
Like silicon, MoS2 has crystalline lattice structure, but electrons do not move as easily through MoS2 as they do with silicon in which electrons become out of control when the gate becomes too small.
Silicon transistors are likely to fail when the gate length falls below 5 nanometers, but using MoS2, scientists were able to make the gate and the transistor much smaller without it being susceptible to gate-crashing electrons creating what to date is the smallest transistor with a 1-nanometer gate.
"Scaling of silicon (Si) transistors is predicted to fail below 5-nanometer (nm) gate lengths because of severe short channel effects," researchers reported in their study, which was published Oct. 7 in the journal Science. "As an alternative to Si, certain layered semiconductors are attractive for their atomically uniform thickness down to a monolayer, lower dielectric constants, larger band gaps, and heavier carrier effective mass."
Researchers, however, said that their work is just a proof of concept, and there is still much more work to do to put this technology to use. Researchers, for instance, need to identify ways to produce and manufacture these devices on a large scale, which would require future innovations.
"It's a proof of concept," said Javey. "We have not yet packed these transistors onto a chip."