Electron Energy Barriers Between Conducting Materials and Insulating Oxides

Internal Photoemission Spectroscopy Measurements of Interfacial Energy Barriers in Operating TaN/Hf0.5Zr0.5O2/TaN Metal/Ferroelectric/Metal (MFM) Devices

“…The change in slope seen in all curves at 4.1 eV and the yield behavior between 4.1 to 5.2 eV was consistent with an optical absorption observed between approximately 4 and 5 eV in ALD-prepared HZO that was attributed to V O + as well as REELS feature starting at about 1 eV below the CB of Ar + sputtered HfO 2 . − This energy range was also consistent with modeling and ab initio DFT calculations of V O + energy levels. ,− The decreased yield slope in this range was thus likely due to photoemission from the HZO VB into oxygen vacancies competing with IPE as well as possibly neutralizing some positive charge which could inhibit IPE. The onset of the slope change remains approximately the same for pristine, woken, and poled devices for emission from both top and bottom interfaces, indicating the energy levels of these defects was not significantly impacted by these electrical operations.…”