Moore's Law states that the number of transistors that can be placed inexpensively into an integrated circuit will double every two years or become half their original size. In reality, it turns out that the doubling/shrinking happens every 18 months. Based on prediction, the law will hold true until somewhere between 2015 and 2020. At which point, a single transistor will be the size of one atom.
Can single atom transistors exist? The answer is shocking; yes, they already do.
3D model constructed by a scanning tunnelling microscope of the single atom Phosphorus transistor (via UNSW)
Researchers at the University of New South Wales (UNSW), Australia, have precisely placed a single phosphorus atom between atomic-scale electrodes and control gates. UNSW Professor Michelle Simmons, leader of the project at the ARC Centre for Quantum Computation and Communication Technology, explained, "...this device is perfect... This is the first time anyone has shown control of a single atom in a substrate with this level of precise accuracy. Our group has proved that it is really possible to position one phosphorus atom in a silicon environment - exactly as we need it - with near-atomic precision, and at the same time register gates."
Inside a high-vacuum chamber, the team used a scanning tunnelling microscope (STM) to see/manipulate the atom on the crystalline substrate. A lithographic process was used to pattern the phosphorus atom into a usable transistor. A non-reactive layer of hydrogen was applied to the atomic circuit. The STM then removed selected hydrogen atoms, etching the surface. A chemical reaction placed the phosphorus atoms in the center. Then everything is encapsulated in silicon. Connections through the silicon allow for control on the individual atoms. The results were theoretical agreement with what a single phosphorus atom transistor could do.
Although the team stated that they beat Moore's Law, they now have to manufacture inexpensive devices using the technology to solidify an actual law-break. They have only 3 years to do it. I am hoping they do so. Keep in mind, controlling individual atom is at the core of quantum computing, and this might just bring about the technological singularity much faster. (When innovation can happen in an instant, every instant.)