NIMS Award Symposium 2023｜Abstracts

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High Thermal Stability for Boron-Doped Diamond Field-effect Transistors Jiangwei Liu,1 Tokuyuki Teraji,1 Bo Da2 and Yasuo Koide1 1 , National Institute for Materials Science (NIMS) 2 Center for Basic Research on Materials, National Institute for Materials Science (NIMS) Wide-bandgap semiconductor diamond has excellent intrinsic properties over other semiconductors, such as high critical breakdown field, large thermal conductivity, and high hole mobility. Diamond-based electronic devices are considered promising as they operate well with low power loss, high power-frequency, and high thermal limitation. Recently, p-type hydrogen-terminated diamond (H-diamond) and boron-doped diamond (B-diamond) field-effect transistors (FETs) have been developed greatly. However, with increase of annealing temperature, the H-diamond surface channel was damaged gradually and electrical properties of the H-diamond FETs were degraded greatly. The B-diamond-based FETs are considered to be operating well at high temperature. However, due to the high activation energy for boron dopants (370 meV) at room temperature, hole density in the B-diamond was quite low and the B-diamond-based FETs operated with low output current and extrinsic transconductance. In this work, we will demonstrate our recent studies for the B-diamond-based FETs with high output current and good thermal stablity at high-temperature [1-4]. References [1] J. Liu, T. Teraji, B. Da, and Y. Koide, IEEE Electron Dev. Lett. 40, 1748–1751 (2019). [2] J. Liu, T. Teraji, B. Da, H. Oosato, and Y. Koide, IEEE Tran. Electron Dev. 67, 1680-1685 (2020). [3] J. Liu, T. Teraji, B. Da and Y. Koide, IEEE Tran. Electron Dev. 68, 3963–3967 (2021). [4] J. Liu, T. Teraji, B. Da and Y. Koide, IEEE Tran. Electron Dev. 70, 2199–2203 (2023). Effects of Temperature and Strain Rate on MEntropy Alloy R. Harada1, N. Tsuchida2, R. Ueji3 and H. Somekawa3 1 Graduate Student, Department of Materials and Synchrotron Radiation Engineering, University of Hyogo 2 Department of Materials and Synchrotron Radiation Engineering, Graduate School of Engineering, University of Hyogo 3 Research Center for Structural Materials, National Institute for Materials Science (NIMS) High entropy alloys (HEA) consist of five or more elements with equal or nearly equal atomic weight. Although it has been reported that combinations of elements exhibit excellent mechanical properties at cryogenic and high temperatures, there are few reports on the strain rate dependence. Thus, this study investigated the effects of strain rate and temperature on the mechanical properties of FeMnNiCoCr HEA. Tensile tests were conducted at deformation temperatures between 77 and 673 K and strain rates between 103 and 10-4 s-1. In the mechanical properties obtained from static tensile tests, 0.2% proof stress and tensile strength increased, and uniform elongation improved significantly below 296 K. Deformation twins are responsible for improving mechanical properties at low temperatures from SEM observations. The tensile test results at strain rates above 101 s-1 showed that the temperature increase due to adiabatic heating and the stress increase due to strain rate canceled each other out, resulting in little change in uniform elongation. The volume fraction of the deformation twin is expected to decrease due to the adiabatic heating at high strain rates above 101 s-1. Poster Presentation ｜NIMS Award Symposium 2023 P2 ｜ Characterizationechanical Properties in FeMnNiCoCr High PP22--1199 PP22--2200 53