Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 12: HL Poster I
HL 12.60: Poster
Montag, 1. April 2019, 17:30–20:00, Poster E
Structural, Energetic and Electronic Properties of Lanthanum and Fluorine Doped HfO2/SiO2 Gate Stack of MOSFETs — Arash Rahimi1, •Ebrahim Nadimi1,2, and Michael Schreiber2 — 1Faculty of Electrical Engineering, Center for Computational Micro and Nanoelectronics, K. N. Toosi University of Technology, Tehran, Iran. — 2Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany.
Aggressive down scaling of the dimensions of metal-oxide-semiconductor field-effect transistors requires the application of high-k gate dielectrics in order to keep the gate leakage current at an acceptable level. Among several candidates HfO2-based high-k gate stacks have been shown to be the most promising solution. However, the high-k gate stacks suffer from high density of trap levels as well as difficulties in threshold voltage adjustment. Doping of the gate stack with different atoms such as La and F has been shown to improve the gate stack quality. We employed first-principles calculations to investigate different atomic structures for La and F doping agents and their interactions with oxygen vacancies in a SiO2/HfO2 gate dielectric stack. The formation energies are calculated for different configurations and the results show that the F atoms prefer to occupy the position of an oxygen vacancy, particularly at the SiO2/HfO2 interface. The energetically favored configuration for a La defect complex is also located at the HfO2 layer close to the interface. F and La doping is shown to be applicable for the passivation of trap levels as well as for the adjustment of the threshold voltage.