It has long been thought that building nanometer-sized transistors was impossible. Simply put, the physics and atomic structural imperfections couldn’t be overcome. However, scientists built fully functional, nanometer-sized transistors. They did so using atomically flat, two-dimensional molybdenum disulfide semiconductor and a single-walled carbon nanotube imbedded in zirconium dioxide.
Moore’s law states that the number of transistors per square inch on a microchip has doubled every year since they were invented. This has been realized by the ability to decrease the size of a transistor. However, when the gate length of the transistors approaches 5 nanometers, it was believed that our ability to continue to shrink a transistor size would reach its limit. Below this feature size, it was not clear how to build next-generation devices. The result of this research shows that it is feasible to continue to reduce the size of a transistor, all the way down to 1 nanometer.
The next generation of microelectronics will only be realized by finding ways to continue to reduce the size of a transistor. Since the introduction of integrated circuits, the observation referred to as Moore’s law has been met — about every year, the number of transistors per unit area has doubled continuously, which is a direct consequence of our ability to continue to decrease the size of a transistor. The gate length of a transistor is the defining parameter of the transistor size, and is presently about 20 nanometers in commercial electronic chips. It is not possible to shrink it below 5 nanometers using silicon. However, researchers have demonstrated that using the semiconducting material molybdenum disulfide (MoS2) and single-walled carbon nanotubes, the transistor gate length can be reduced to a record size of 1 nanometer. The team used these materials to fabricate a fully operational transistor. These novel materials are atomically uniform at a thickness down to a monolayer. In comparison to current materials, these newly discovered materials have lower dielectric constants, larger band gaps, and a larger carrier effective mass making them ideally matched to the device requirements. The characteristics of the nanometer-sized transistor have been measured and show a subthreshold swing ~65 mV/decade and On/Off current ratio ~106. This work demonstrated the shortest transistor ever and that Moore’s law can continue a while longer by proper engineering of the semiconductor material and device architecture.