Zheng Fang; Xin Peng Wang; Joon Sohn; Bao Bin Weng; Zhi Ping Zhang; Zhi Xian Chen; Yan Zhe Tang; Guo-Qiang Lo; Provine, J.; Wong, S.S.; Wong, H.-S.P.; Dim-Lee Kwong, "The Role of Ti Capping Layer in HfOx-Based RRAM Devices," Electron Device Letters, IEEE , vol.35, no.9, pp.912,914, Sept. 2014 doi: 10.1109/LED.2014.2334311
In this letter, we examine the role of the Ti capping layer in HfOx-based resistive random access memory (RRAM) devices on the memory performance. It is found that with a thicker Ti capping layer, the fresh device initial leakage current increases and as a result, the forming voltage decreases. In addition, with a thin Ti layer of <3 nm (on top of 8-nm HfOx ), there is no resistive switching, while by inserting a thicker Ti
layer of 10 nm, the memory window enlarges to about two orders. Very good uni formity has also been observed in thick Ti capping devices, demonstrating the effectiveness in RRAM device engineering. It is believed that the Ti layer serves as an oxygen reservoir, by extracting oxygen during device formation
and electrical forming process and facilitates resistive switching thereafter.
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