Controlling the assembly of atoms

University of Canterbury scientists have discovered a new way of assembling atoms that could lead to increases in the power of mobile phones, computer tablets and memory sticks.

UC physics professor Simon Brown is investigating the possibility of much smaller electronic devices with more power and data storage.

“The ultimate limit is to build things one atom at a time. We aren’t there yet but our recent paper describes a new tool that can be used to control the assembly of atoms,” he said.

“Silicon chips are built using a process called lithography, where a large piece of silicon is sculpted so as to produce the tiny devices (called transistors) that actually do computing. The semiconductor industry knows that these processes cannot be used at much smaller scales than they are used at present and so it is important to find new ways of building at the nanoscale.”

This discovery provides a new way of controlling the formation of nanoscale structures as part of the research. The UC scientists involved in this work are part of the MacDiarmid Institute for Advanced Materials and Nanotechnology, which is a government-funded centre of research excellence.

Many other important products are being enabled by nanotechnology, such as a range of medical diagnostic devices which rely on tiny nanoscale sensing elements.

“Those nanoscale elements are critical to the way the sensors work,” Professor Brown explained. “Researchers overseas have built sensors that can detect a single HIV virus, but the problem is that it is difficult to manufacture those devices with current technologies, and so they are not currently available to consumers. That’s why it is important we try to develop new ways of building on this tiny scale.

“The new method harnesses fundamental quantum mechanical principles to ‘self-assemble’ structures that could be used in a range of applications, such as new computer memories and new laser technologies.

“The downstream benefits for the public possibly include new internet and computing technologies, new sensing technologies and new medical diagnostics.

“It is always hard to predict the implications. Very few people in the 1950s could have imagined the enormous impacts of the invention of the transistor. Now we have silicon chips in everything from our mobile phones to our computers to our fridges; we rely on them for an enormous range of activities.”

The experimental work has been conducted by postdoctoral researcher Pawel Kowalczyk and PhD student Ojas Mahapatra under Professor Brown’s supervision and was largely funded by the MacDiarmid Institute. They collaborated with researchers in the United States and China.

“Anyone who has played a musical instrument, or blown across the open end of a bottle or a pipe, knows that the musical note that is produced depends on the length of the instrument,” Professor Brown said. “In fact, to get a nice musical note, the length of the pipe must be just right. It should match the wavelength of the note required.

“In our research we discovered that because of the way quantum mechanics works, the opposite process comes into play on the nanoscale. We found that the structure tunes its size to match the wavelength of the electron waves inside it.

“This technique could be used to control the formation of quantum dots. These tiny light emitting particles are used in a wide range of medical diagnostic technologies. They are a key part of some new cancer diagnosis techniques.”

The new research has been published in the prestigious international journal Nano Letters.