Atom spied interfering with electron flow

 作者:曲歉     |      日期:2019-03-02 02:16:00
By Will Knight An individual “dopant” atom has been spied interfering with the flow of electrons through a silicon transistor for the first time. Researchers say the feat could help scientists squeeze more power out of conventional computers and ultimately develop silicon-based quantum computers. Dopants are chemical impurities that affect the flow of electrons through a conducting or semiconducting material. They are deliberately added to pure silicon, for example, to create different types of electronic component. To analyse a lone dopant atom in action, Sven Rogge and colleagues at Delft University of Technology in the Netherlands cryogenically cooled 35-nanometre-wide silicon wires, taken from commercial field-effect transistors. They then fed a current through the transistor while subtly tuning the voltage at its gate. By focusing on a section of wire just a few cubic nanometres at either end of the transistor and measuring the current flowing through the wire they were able to extrapolate the position of a single dopant atom, and measure its effect on the flow of electrons. The ability to analyse single dopant atoms could help engineers squeeze further power out conventional computer systems, say the researchers. As electronic components are gradually scaled down to nano-dimensions – to pack more power into the same physical area – the precise position and behaviour of each dopant atom becomes crucial to the functioning of that component. “The fact that dopants are randomly spread causes a severe limit on the amount of miniaturisation you can achieve,” Rogge told New Scientist. “We don’t have a solution to that problem but we have the toolbox to study a single impurity.” “The physics is interesting,” adds Laurence Eaves a researcher at the University of Nottingham in the UK, who was not involved in the study. “As it reports results in a silicon-based device, it is clearly of relevance to where electronics will go when Moore’s Law starts to saturate.” Rogge goes on to suggest that the trick could also prove useful to the development of silicon-based quantum computers. This would involve an architecture proposed by Bruce Kane, of the University of Maryland, US, in which the spin state of individual electrons and atoms within silicon are used to perform quantum calculations. “If you want to do something in silicon on the quantum scale with an impurity atom, you have to understand how those atoms will behave,