Transistors are the fundamental building blocks of most electronics, including all computers and radios. A nanotransistor is a transistor whose dimensions are measured in nanometers. For instance, a transistor with a diameter of 300 nanometers (billionths of a meter) would be a nanotransistor. Transistors are used for switching and amplifying electronic signals. When combined in the millions and billions, they can be used to create sophisticated programmable information processors, more commonly known as computers. Computing and communications companies invest hundreds of millions of dollars in research funds every year to develop smaller transistors.
Miniaturizing the transistor has been the hallmark of 50 years of progress in smaller computers. In a trend known as Moore's law, the number of transistors that engineers have been able to fit on a chip of fixed size has consistently doubled every 18 to 24 months. Thus, the entire history of computing has consisted of many dozens of doublings. Unfortunately for the computing industry, however, this trend cannot be maintained forever -- the tiny size of current transistors is starting to run up against the laws of physics.
Efforts to fabricate a smaller nanotransistor are a push to fulfill Moore's law and providing better and faster electronics to customers. Conventional photolithography offers limits to how small a nanotransistor can be fabricated, so new approaches are being attempted, including using microbes and slow chemical vapour deposition to synthesize transistor components. The effort to make nanotransistors is on the forefront of nanotechnology.
In November 2001, Bell Labs scientists made a major step forward in efforts towards smaller nanotransistors with their fabrication of individually-addressable nanotransistors at the scale of an individual molecule. These devices are so tiny that about 10 million could fit on the head of a pin. The challenge of creating tiny electrodes for these transistors was solved using self-assembly -- putting together molecules in a certain mix that causes them to combine together and self-assemble without direct engineer intervention. Unfortunately however, this approach is still experimental and is not viable for mass manufacturing yet.
In January 2008, another milestone in the development of nanotransistors was made by scientists at the University of Illinois, when they constructed a nanotransistor radio whose active components are exclusively made from carbon nanotubes. Carbon nanotubes are extremely flexible materials with unparalleled strength and usefulness in electronics.
Because nanotransistors are so small, their behavior cannot be entirely described by current theories. Therefore, efforts have been ongoing to develop new theories that can be applied to the nanoscale.