Mixed Oxide High-K Dielectrics - from Gate Dielectrics to Non-Volatile Memories to SSI-LEDs
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Metal oxides were first used as the high-k gate dielectrics in thin film transistors (TFTs). In late 1990s, they were applied to MOSFETs to solve the high leakage current problem in the ultra-thin SiO2 gate dielectric. HfO2 was identified as a viable solution for this application due to its relatively large effective k value and low leakage current. However, HfO2 is subject to crystallization at a relative low temperature of about 600C. We introduced the doping method, i.e., by adding a third element to the metal oxide, to solve this problem. The crystallization temperature, the effective k value, the interface state density, and the interface layer thickness of the new film were influenced by the concentration of the added element (1). Eventually, we demonstrated that the 12% Zr doped HfO2, i.e., ZrHfO, had a crystallization temperature higher than 900C and many good dielectric properties. The ZrHfO thin film can be sputter deposited.In this talk, structures, preparation methods, operation principles, and characteristics of the following devices will be discussed and new developments will be addressed. < 1 nm EOT ZrHfO gate dielectric layers (2),nanocrystals embedded ZrHfO NVMs in which electrons and holes could be stored separately based on the type of nanocrystal material (3), andsolid state incandescent LEDs (SSI-LEDs) which are formed from the thermal excitation of the simultaneous formation of a large number of nano-resistors during the dielectric breakdown process (4,5,6).J.-Y. Tewg, Y. Kuo, and J. Lu, Electrochem. Solid-State Letters, 8(1), G27-G29 (2005).Yan, Y. Kuo, and J. Lu, Electrochem. Solid-State Letts., 10(7), H199-H202 (2007).Zhang and Y. Kuo, ECS Trans., 66(4), 195-202 (2015).Y. Kuo and S. Zhang, ECS J. Solid State Sci. Technol., 8(12), Q223-Q225 (2019).W.-S. Lin and Y. Kuo, ECS J. Solid State Sci. Technol., 10, 126001 (2021).A. Samuel and Y. Kuo, Solid State Electronics, 204, 108651 (2023).
