A new analysis method has been developed that can detect "hidden defects" (electron traps) that disrupt electrical flow inside semiconductors approximately 1,000 times more sensitively than existing techniques.
KAIST announced Wednesday that a joint research team led by Professor Shin Byoung-ha of the Department of Materials Science and Engineering and Dr. Oki Gunawan of IBM T. J. Watson Research Center has developed a new measurement technique capable of simultaneously analyzing defects (electron traps) that interfere with electricity and electron transport characteristics inside semiconductors.
Electron traps that capture electrons and impede their movement can exist inside semiconductors. When electrons become trapped, electricity cannot flow smoothly, causing leakage current or performance degradation. Therefore, accurately evaluating semiconductor performance requires determining how many electron traps exist and how strongly they capture electrons.
The research team focused on Hall measurement, a technique long used in semiconductor analysis. Hall measurement analyzes electron movement using electricity and magnetic fields. The team succeeded in obtaining information that was difficult to confirm with conventional methods by adding illumination and varying temperatures during measurement.
When light is applied weakly, newly generated electrons are first captured by electron traps. Conversely, as light intensity gradually increases, the traps become filled, and subsequently generated electrons begin moving freely. By analyzing this change process, the research team was able to precisely calculate the quantity and characteristics of electron traps.
The greatest advantage of this method is that multiple pieces of information can be obtained simultaneously from a single measurement. It can determine not only how fast electrons move, how long they survive, and how far they travel, but also the characteristics of traps that impede electron movement.
The research team first applied this technique to silicon semiconductors to verify accuracy, then applied it to perovskite, a material attracting attention as a next-generation solar cell material. As a result, they succeeded in precisely detecting very small quantities of electron traps that were difficult to detect with existing methods. This means measurement sensitivity approximately 1,000 times greater than existing technology has been achieved.
"This research presents a new method that can simultaneously analyze electrical flow inside semiconductors and factors that interfere with it through a single measurement," Professor Shin said. "It will become an important tool for improving the performance and reliability of various semiconductor devices including memory semiconductors and solar cells."
The research results were published in the international journal Science Advances on January 1, with doctoral student Kim Chae-yeon of the Department of Materials Science and Engineering as first author.