POSTECH and U.S. SEMATECH explain next-generation nanotransistor degradation. Professor Yoon-Ha Jeong's EE team develops a model predicting degradation in lanthanum-doped transistors, enabling fabricated devices to match design predictions and reducing fabrication time and cost.

A Korean–U.S. team reported research that could improve lanthanum-doped transistors, a promising nanotransistor technology that lowers power consumption by adjusting threshold voltage. POSTECH Professor Yoon-Ha Jeong's team and semiconductor research consortium SEMATECH identified the mechanism linking dipoles and microwave characteristics in lanthanum-doped field-effect transistors and proposed a model.

Presented at the International Electron Devices Meeting (IEDM), a leading semiconductor-device conference, the work should assist fabrication of ultrafast integrated circuits previously hindered by degradation. The microwave behavior of nanotransistors used in phones and computer CPUs had been poorly understood, often causing large discrepancies between designed and fabricated performance. Gain degradation at higher frequencies was a major barrier to accurate prediction and precision fabrication.

The team identified dielectric relaxation of lanthanum-induced dipoles as the cause and incorporated it into a circuit-design model. The model enables advance prediction and prevention of degradation and more accurate designs, reducing fabrication time and cost. SEMATECH's Dr. Chang-Yong Kang praised it as a breakthrough in performance analysis and modeling of ultrafast logic and microwave integrated circuits.

Support came from the Ministry of Education, Science and Technology's WCU IT Convergence Engineering (ITCE) program and BK21, and the Ministry of Knowledge Economy's National Center for Nanomaterials Technology (NCNT).

Glossary: Threshold voltage is the minimum voltage needed to form a current-conducting transistor channel. Lanthanum (La), atomic number 57, is a silvery-white metal, the most reactive rare-earth element, soft enough to cut with a knife. Doping intentionally adds small amounts of another material to improve properties. A dipole is a pair of equal, opposite charges whose centers do not coincide.

Dielectric relaxation: At sufficiently low frequencies, dipoles can reach equilibrium before the electric field changes. If the medium's viscosity prevents them from following changes, electric-field energy is absorbed and lost. SEMATECH is a public–private semiconductor consortium established in 1987 to improve U.S. manufacturing processes and competitiveness; members include Intel, AMD, IBM, Samsung Electronics and Texas Instruments.