Forming Free Bipolar ReRAM of Ag/a-IGZO/Pt with Improved Resistive Switching Uniformity Through Controlling Oxygen Partial Pressure

Abstract

Bipolar resistive switching properties of Ag/a-IGZO/Pt structure resistive random-access memories (ReRAMs) were investigated. The amorphous In-GaZn-O (a-IGZO) films were prepared by a radio frequency magnetron sputtering system at room temperature in mixed gas ambient of argon (Ar) and oxygen (O 2 ). The oxygen partial pressures during sputtering deposition were varied from 0% to 17% to engineer defects in an a-IGZO layer. When the oxygen partial pressure increased to 17%, forming-free bipolar resistive switching properties were observed with nearly 100% device yield. In addition, the forming-free ReRAM device presents an enhanced resistive switching uniformity and an enhanced endurance. The forming-free resistive switching is attributed to the concentration of oxygen-related defects in an a-IGZO thin film via analyses of x-ray photoelectron spectroscopy and current-voltage (I-V) curves, with which it is possible to reduce the forming energy of silver (Ag) conductive filaments.

Performance improvement of amorphous indium–gallium–zinc oxide ReRAM with SiO2 inserting layer

“…The different conduction behaviors in the HRS and LRS suggest that the high conductivity in On-state cell is likely to be a confined effect rather than a homogenously distributed one. The similar IeV characteristics had been observed in the Ag/a-IGZO/Pt ReRAM structure reported in our previous work [12]. Ohmic and SCLC current are bulk dominated mechanisms.…”

“…In addition, the temperature coefficient of resistance of the filaments corresponds with the value for Ag/a-IGZO/Pt structure reported in our previous work [12], which is 6.9 Â 10 À3 K À1 . The results suggest that the filaments are composed of Ag in metallic states due to the diffusion of the top electrode under a bias voltage.…”

High-Performance InGaZnO-Based ReRAMs

“…The memory windows reached 10 5 within 100 endurance cycles. Such a switching ratio is orders of magnitude higher than that of the previously reported IGZO-ReRAMs [25]- [27], [38]- [40]. Furthermore, the memory window of our ReRAMs remains nearly constant during a Pengfei Ma, Guangda Liang, Yiming Wang, Yunpeng Li, Qian Xin, Yuxiang Li, and Aimin Song, Senior Member, IEEE High-performance InGaZnO-based ReRAMs w retention test of 10 5 s. The conduction and switching mechanism was also analysed by examining different possible models.…”

“…Our previous work demonstrated that IGZO TFTs are suitable for future wearable and other low-power electronics because of their high yield and low operation voltages [19], [20]. IGZO films have recently been found to exhibit resistance switching properties [25]- [29]. Liu et al demonstrated an integration of IGZO TFT and ReRAMs to form a one-transistor-one-resistor (1T1R) configuration [30].…”

“…Unfortunately, the IGZO-based ReRAMs fabricated at room temperature generally showed a small memory window (i.e. the on/off ratio was mostly between 10 and10 2 ) [25]- [29]. Furthermore, multi-level memory devices have been proposed for 3D NAND flash [31], [32].…”