– KAIST-Berkeley University Joint Research Team
– Enhancing the Accuracy of Ferroelectric Measurement Technology
[Herald Economy = Koo Bon-hyuk] The cause of errors encountered when measuring special electronic devices with ultra-precise microscopes capable of observing dimensions as small as tens of thousands of times smaller than a hair’s thickness has been revealed. A joint research team from South Korea and the United States discovered that the error, previously attributed to the characteristics of the material being measured, was actually due to an ultra-fine gap between the microscope probe tip and the material surface. This study is expected to greatly contribute to the advancement of technology related to accurately analyzing the characteristics of nanoscale materials used in semiconductors, memory devices, and sensors.
KAIST announced on the 18th that a research team led by Professor Hong Seung-beom from the Department of Materials Science and Engineering has collaborated with Professor Lane Martin’s team from the University of California, Berkeley. Together, they have identified the key factor hindering signal accuracy in scanning probe microscopy and developed a groundbreaking method to control it.
The research team discovered that a non-contact dielectric gap between the microscope probe and the sample surface is a primary cause of measurement errors. This gap can easily be modulated in the measurement environment or filled with contaminants, greatly impacting electrical measurements.
They devised a method using high-dielectric constant fluids like water to fill this gap, enhancing the precision of nanoscale polarization switching voltage measurements by over eight times. This approach yields results that nearly match those obtained using a conventional symmetric capacitor structure, opening a new chapter in the analysis of ferroelectric thin films’ characteristics.
Notably, when water was used as a medium on lithium niobate (PPLN, a special crystal used in optical and electronic devices), which has regularly aligned electrical characteristics up and down, they succeeded in achieving piezoresponse force microscopy (PFM) measurements with significantly higher accuracy than before.
In the dielectric gap controlled by water, the asymmetry between different polarization signals dropped to below 4%. This is analyzed as a result of water molecules neutralizing surface charges and minimizing the effect of electrostatic forces, similar to how static electricity on dry winter days can be eliminated with water.
Professor Hong Seung-beom remarked, “This discovery is a foundational study that can solve the uncertainty issues of nanoscale measurement technology using fine probes,” adding, “It can be widely applied to the analysis of electrical characteristics of various functional materials, not just ferroelectrics.”
The research results were published in the September 2nd issue of the international journal ‘Advanced Functional Materials’ in the field of materials science.