Ivan Alejandro Velasco-Davalos
PhD student in Energy Science and Materials
Award winning publication: Realization of Single-Termination SrTiO3 (100) Surfaces by a Microwave-Induced Hydrothermal Process
Published in: Applied Physics Letters, vol. 103, no 202905, 2013
"For most oxide-based nanoelectronic and superconductor applications, epitaxial growth is an absolute prerequisite, and strontium titanate (100) surfaces are the default substrate in thousands of laboratories (research and industry) all around the world. The standard etching procedure to achieve atomically flat and TiO2 terminated surfaces is based on a buffered HF (dilute hydrofluoric acid) dip and has two major disadvantages: a) the results for pure and niobium-doped (metallic) SrTiO3 surfaces are different and require different protocols; b) HF is highly corrosive, toxic and requires substantial storage, handling and disposal precautions. My process is based on pure water and a hydrothermal plastic reactor in a commercial microwave oven at a total cost of less than $1,000. The microwave-assisted step takes Iess than 3 minutes and works equally well for pure and Niobium-doped samples. It also excludes the possibility of a fluorine contamination as introduced by HF. Being safer, faster, and by far less expensive and leading to better sample properties, I am convinced that my process will soon become the new standard."
The procedure proposed by the author would have multiple immediate impacts: first of all, it eliminates the reported typical fluorine contamination; secondly, it increases work safety by the use of a moderately pressurized container of hot water, at the same time reducing problematic laboratory waste. Not only was this protocol adopted by several research groups in Canada and the US, but it has also started to attract interest in some emerging and developing countries. This study opens the door for a whole new research community with limited resources.