Impedance spectroscopic analysis on effects of partial oxidation of TiN bottom electrode and microstructure of amorphous and crystalline HfO2 thin films on their bipolar resistive switching.
Impedance spectroscopic analysis on effects of partial oxidation of TiN bottom electrode and microstructure of amorphous and crystalline HfO2 thin films on their bipolar resistive switching.
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DOI：
10.1039/c4nr00507d
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发表时间：
2014-05
期刊：
影响因子：
6.7
通讯作者：
Ji-Wook Yoon;J. Yoon;Jong‐Heun Lee;C. Hwang
中科院分区：
文献类型：
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作者：
Ji-Wook Yoon;J. Yoon;Jong‐Heun Lee;C. Hwang
使用直流电流-电压 (I-V) 扫描和交流阻抗谱 (IS) 分析，检查了通过原子层沉积在 TiN 基底上生长的非晶 HfO2 (a-HfO2) 和结晶 HfO2 (c-HfO2) 薄膜的电阻切换 (RS) 特性。 a-HfO2 薄膜在 N2 气氛下于 500 °C 快速热退火 5 分钟，使 HfO2 薄膜结晶并产生界面 TiON 阻挡层。 a-HfO2 样品表现出流畅的双极性 RS 性能，具有高开/关比 (∼ 500)，而 c-HfO2 样品则表现出低得多的开/关比 (<∼ 10)，但其开关均匀性优于 a-HfO2。这种关键差异主要归因于 a-HfO2 和 c-HfO2 样品中分别不存在和存在 TiON 阻挡层。 AC IS 尤其能够在每个样品的一个完整开关周期内分别检查 HfO2/Pt 界面和 HfO2/TiN 界面的电阻状态。尽管Pt/c-HfO2界面在原始状态下具有肖特基势垒，但一旦c-HfO2电铸，肖特基势垒就消失，并且即使在重置步骤之后也没有恢复。相比之下，Pt/a-HfO2 界面在复位后部分恢复了肖特基势垒。
The electrical resistance switching (RS) properties of amorphous HfO2 (a-HfO2) and crystalline HfO2 (c-HfO2) thin films grown on a TiN substrate via atomic layer deposition were examined using DC current-voltage (I-V) sweep and AC impedance spectroscopic (IS) analyses. The rapid thermal annealing of the a-HfO2 film at 500 °C under a N2 atmosphere for 5 min crystallized the HfO2 film and induced an interfacial TiON barrier layer. The a-HfO2 sample showed fluent bipolar RS performance with a high on/off ratio (∼ 500), whereas the c-HfO2 sample showed a much lower on/off ratio (<∼ 10), but its switching uniformity was better than that of a-HfO2. Such critical differences can be mainly attributed to the absence and presence of the TiON barrier layer in the a-HfO2 and c-HfO2 samples, respectively. The AC IS especially enabled the resistance states of the HfO2/Pt interface and the HfO2/TiN interface to be separately examined during one complete switching cycle of each sample. Although the Pt/c-HfO2 interface has a Schottky barrier in the pristine state, it disappeared once the c-HfO2 was electroformed and was not recovered even after the reset step. In contrast, the Pt/a-HfO2 interface partly recovered the Schottky barrier after the reset.