A team based at the University of New South Wales has created a "perfect" single atom transistor, leading the way for smaller and more powerful electronics. The active component in the device is a single phosphorus atom, which is placed onto a silicon wafer using a combination of scanning tunnelling microscope microscopy (STM) and hydrogen-resist lithography. To achieve this, a silicon wafer is coated in hydrogen, before individual hydrogen atoms are lifted away using STM. The wafer is then treated with phosphene, which only binds to the silicon at points where the hydrogen has been removed (similar to creating a circuit board in an acid bath, where the masked areas don't get cut away). The same universities are behind the one-atom high wire, which has been hailed as a huge step in the development of quantum computing.
While single-atom transistors have been created before, the team says that it's the first to be able to produce them reliably, with others often stumbling across the transistors by accident and being unable to replicate the results. The team see this atom-by-atom method (known as bottom-up) of building transistors as the future of creating smaller and more powerful circuits, saying that the current top-down method of production will be unable to match this accuracy with any degree of reliability. Professor Michelle Simmons, the group leader behind the project, says that "This is the first time that anyone has shown control of an atom in a substrate with this level of accuracy."