A precise science
Clotilde Lethiec - 26 January 2018
When 18-year old Paul Kim arrived in Canada with his family in the early 2000s, he did not have precise plans for his future. After finishing school in Toronto, he moved to Alberta and held for a few years a number of small jobs in Edmonton. But what Kim wanted was a career, not a job.
"Since I have always enjoyed learning, I thought: ‘Why not make a living out of it?’" said Kim. As he was initially interested in chemistry, he decided to enroll in a science program at Grant MacEwan College. There, one of his instructors passed on to him a taste for physical sciences.
"I really learned to appreciate the bottom-up approach in physics," said Kim, who has since developed the deep nanofabrication skills to measure and control mechanical motions at the quantum level.
In 2010, Kim joined the Davis group in the Department of Physics to work on his fourth-year undergraduate project. Back then, he worked on techniques to study the optical and mechanical properties of industrially nanofabricated devices such as nano-chips. But by the time Kim received these prefabricated devices, they were no longer cutting-edge samples. After entering into the MSc program, he started training on nanofabrication techniques at the University of Alberta Centre for Nanofabrication (nanoFAB).
"After long hours, my newly built fabrication skills allowed me to make my own state-of-the-art samples," Kim said.
Man vs. machine
Today, as a PhD student, Paul is one of the advanced "super-users" at the nanoFab. As a good team member, Kim is also often making devices that will be used for the experiments of other students in the Davis’ research group. He is the lead author of two recent Nature Communications articles about measuring mechanical displacements at the nanoscale. These papers rely on Kim’s ability to fabricate very precise three-dimensional devices. He achieves a gap between the optical and mechanical components of just a few tens of nanometers, a resolution that tests the limits of the nanoFAB’s machines.
"I didn’t think we would be able to make devices this good with our current nanofabrication equipment," said Kim’s supervisor, John Davis, an associate professor in the Department of Physics. "He has really pushed the limit of what is possible."
For example, in his 2016 paper, Kim implemented a complex double lithography procedure which enabled him to align and land an aluminum disk onto his device with a precision of just 5-10 nm.
Kim’s second paper was made possible by the new "vapour etcher" in nanoFAB, of which Kim was one of the first users. The vapour etcher enables the fabrication of devices with an unprecedented precision.
"Paul’s desire to be at the cutting-edge of nanofabrication led him to imagine how this new tool would aid in making better devices," Davis said. "When there is a new tool that enables new abilities, Paul pushes the very limits of it. Fantastic science always pops up with new capabilities like these."
Future possibilities
Kim’s final challenge as a PhD student is to create devices with superconducting components operating at very low temperature. "We have shown that we have interesting capabilities at room temperature, and that we have amazing sensitivity at low temperatures," said Kim. "Now we just have to put these two aspects together. We hope to uncover some fundamental physics of superconductivity that has never been seen before."
Kim recently won the 2017 nanoFAB image contest and the 2017 Raith Micrograph Award, which will sponsor his travel to attend an international nanotechnology related conference of his choice. He is planning to use this to attend the SpinMechanics conference in French Alps. In addition, the nanoFab was recently awarded a $6.2 million grant from the CFI Innovation Fund, of which a major portion has been earmarked for a new high-energy electron-beam lithography system, a technique that enables to draw patterns in extremely small dimensions. The higher energy will allow for higher-resolution lithography than what is currently possible. "I can’t wait to see what Paul will be able to make with that system once it arrives," Davis said.
Even at present, Davis is impressed by Kim’s abilities. While in my office for this interview, Davis pointed to a computer image depicting the precise disk alignment that Kim performed. "This is a work of art," Davis said. However, Kim was less enthusiastic, saying, "This disk is a bit skewed though."