Atomic-scale characterization of defects generation during fatigue in ferroelectric Hf_0.5Zr_0.5O₂ films: vacancy generation and lattice dislocation

Fatigue Mechanism of Antiferroelectric Hf0.1Zr0.9O2 Toward Endurance Immunity by Opposite Polarity Cycling Recovery (OPCR) for eDRAM

“…According to previous research reports, the FE fatigue and degradation are dominated by (i) the m-phase increment, (ii) breakdown, and/or (iii) dipole pinning, as shown in Fig. 5(a) [1], [3], [4], [11], [12], [13], [14], [15], [16]. Three fatigue mechanisms are discussed for AFE and validated by experimental measurements as follows.…”

“…Three fatigue mechanisms are discussed for AFE and validated by experimental measurements as follows. For (i) m-phase formation, the lattice dislocation is located in the FE orthorhombic phase (o-phase) grain with a large grain size to form the non-FE monoclinic phase (m-phase) with cycling to lead to endurance fatigue for FE Hf 0.5 Zr 0.5 O 2 [11], [12]. However, the relative permittivity remains almost unchanged with endurance cycles for the AFE, even when 2P r decreases as shown in Fig.…”

“…3, the AFE domains can be divided into positive and negative polarities independent of the tetragonal phase, which is notably different from the orthorhombic-based FE system. For the recovery by high E-field stimulation on bipolar AFE cycling, VOs are [1], [3], [4], [11], [12], [13], [14], [15], [16]. (b) Comprehensive model for AFE fatigue and recovery with high E-field stimulation (black path), OPPR (blue and green paths), and OPCR (red path).…”

“…5. (a) According to previous research reports, the FE fatigue and degradation are dominated by (i) m-phase increment, (ii) breakdown, and/or (iii) dipole pinning[1],[3],[4],[11],[12],[13],[14],[15],[16]. (b) Comprehensive model for AFE fatigue and recovery with high E-field stimulation (black path), OPPR (blue and green paths), and OPCR (red path).…”

First direct observation of the built-in electric field and oxygen vacancy migration in ferroelectric Hf0.5Zr0.5O2 film during electrical cycling

“…In view of these competing theories, direct observation of the above nanoscale processes is essential to unravel the true cause of wake-up and fatigue effects. Although field-induced phase transition was recently detected in ferroelectric HfO 2 film during field cycling, [18][19][20] nanoscale imaging of the builtin electric field or oxygen vacancy migration is a very challenging task and has not been reported so far, which has obscured further insight into the mechanism of wake-up and fatigue effects.…”