Shajil Nair Keerthana, Holzer Marco, Dubourdieu Catherine, Deshpande Veeresh
Helmholtz-Zentrum-Berlin für Materialien und Energie, Institute "Functional Oxides for Energy Efficient Information Technology", Hahn-Meitner Platz 1, 14109 Berlin, Germany.
Physical Chemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany.
ACS Appl Electron Mater. 2023 Mar 10;5(3):1478-1488. doi: 10.1021/acsaelm.2c01492. eCollection 2023 Mar 28.
The wake-up behavior and ON/OFF current ratio of TiN-AlO-HfZrO-W ferroelectric tunnel junction (FTJ) devices were investigated for different wake-up voltage waveforms. We studied triangular and square waves, as well as square pulse trains of equal or unequal voltage amplitudes for positive and negative polarities. We find that the wake-up behavior in these FTJ stacks is highly influenced by the field cycling waveform. A square waveform is observed to provide wake-up with the lowest number of cycles, concomitantly resulting in higher remnant polarization and a higher ON/OFF ratio in the devices, compared to a triangular waveform. We further show that wake-up is dependent on the number of cycles rather than the total time of the applied electric field during cycling. We also demonstrate that different voltage magnitudes are necessary for positive and negative polarities during field cycling for efficient wake-up. Utilizing an optimized waveform with unequal magnitudes for the two polarities during field cycling, we achieve a reduction in wake-up cycles and a large enhancement of the ON/OFF ratio from ∼5 to ∼35 in our ferroelectric tunnel junctions.
针对不同的唤醒电压波形，研究了TiN-AlO-HfZrO-W铁电隧道结（FTJ）器件的唤醒行为和开/关电流比。我们研究了三角波和方波，以及正负极性下电压幅度相等或不相等的方波脉冲序列。我们发现，这些FTJ堆叠中的唤醒行为受场循环波形的影响很大。与三角波形相比，观察到方波形以最少的循环次数实现唤醒，同时导致器件中更高的剩余极化和更高的开/关比。我们进一步表明，唤醒取决于循环次数，而不是循环期间施加电场的总时间。我们还证明，为了实现有效的唤醒，在电场循环期间正负极性需要不同的电压幅度。通过在电场循环期间使用针对两种极性具有不相等幅度的优化波形，我们在铁电隧道结中实现了唤醒循环次数的减少以及开/关比从约5大幅提高到约35。
