Impact of vacancies and impurities on ferroelectricity in PVD- and ALD-grown HfO2 films

Abstract

Note: This paper is part of the Special Topic on Materials and Devices Utilizing Ferroelectricity in Halfnium Oxide.

Chemical Stability of IrO2 Top Electrodes in Ferroelectric Hf0.5Zr0.5O2‐Based Metal–Insulator–Metal Structures: The Impact of Annealing Gas

“…In a previous study, we have revealed such a process by the incorporation of nitrogen in HfO 2 . [ 27 ] As vacancy gap states are mainly expected near the conduction band minimum (CBM), [ 26,28 ] such passivation should result in a Fermi level shift toward the valence band maximum (VBM), and, in accordance, a rigid core‐level shift toward lower binding energies was observed for nitrogen incorporation. [ 27 ] In the present study, we do not observe a core‐level shift for FGA samples toward lower binding energies, but, in contrary, toward higher ones and, hence, conclude that hydrogen does not passivate existing defect states in HZO but introduces additional ones.…”

An Overview of Ferroelectric Hafnia and Epitaxial Growth

“…In this sense, the ferroelectric behavior such as fatigue and imprint field would degrade under high oxygen vacancies. [ 99,100 ] Although no significant influence of the oxygen content on retention, it was observed that fatigue was less in films grown under low oxygen concentrations. In addition, the imprint field relies greatly on oxygen concentration, increasing from a negligible value at 0.01 mbar to ≈400 kV cm −1 at 0.1 mbar.…”

Interplay between oxygen defects and dopants: effect on structure and performance of HfO2-based ferroelectrics

“…In a recent publication, Baumgarten et al 32 compared ALD and PVD deposited undoped HfO 2 layers where oxygen was supplied through 10 and 60 s ozone pulses and 0 and 2 sccm oxygen flow for the two processes, respectively. Hard X-ray photoelectron spectroscopy (HAXPES) results for the PVD layers confirmed the expected trends: a higher O 2 flow translated into a better oxidized layer and in weaker ferroelectricity.…”