The Effect of Al and Ni Top Electrodes in Resistive Switching Behaviors of Yb2O3-Based Memory Cells

Abstract

In this letter, the effect of Al and Ni top electrodes in resistive switching behavior of Al/Yb 2 O 3 /TaN and Ni/Yb 2 O 3 /TaN memory devices is proposed. The Al/Yb 2 O 3 /TaN memory device demonstrates no such switching performance as applying bias on both top and bottom electrodes, whereas the Ni/Yb 2 O 3 /TaN reveals the bipolar memory switching behavior with a high resistance ratio of 10 4 for over 200 cycles of switching responses and good data retention with memory window of about 10 5 at 85 • C, as extrapolated up to 10 years. The resistance switching dynamic is ascribed to the conductivity modulation by oxygen ions/vacancies controlled electrochemical reaction process in the Yb 2 O 3 switching layer.Resistive random access memory (ReRAM) is an emerging storage device for next generation high potential nonvolatile memory (NVM) applications due to its scaling ability, low cost, and compatibility of being integrated in back-end-of-line (BEOL) process in complementary metal-oxide-semiconductor (CMOS) fabrication. 1-7 A simple ReRAM device structure usually consists of an oxide layer sandwiched between two metal electrodes. Application of low voltage electrical pulse with certain level can change the oxide's resistance significantly between two stable states, namely high resistance state (HRS) and low resistance state (LRS). Nonvolatile resistive switching behavior has been demonstrated for several binary oxides, including . 8-13 Although resistance-switching phenomena in several binary metal oxides have been known from decades, the details of the switching mechanisms and the nature of the different resistive states are still under debate. Different switching models such as domain and tunneling model, 14 filament model, 15,16 and field induced crystallinity and charge trapping model [17][18][19] have been studied extensively. However, exact switching phenomena are not clearly understood yet. In this letter, we explored an improved resistive switching behavior of Ni/Yb 2 O 3 /TaN memory cells in compare with Pt/Yb 2 O 3 /TiN memory cell. 13 Additionally, the influence of top electrode material (Ni and Al) on the electrical properties of Yb 2 O 3 -based ReRAM is discussed to realize for next generation universal memory application.It is found that the bipolar resistive switching behavior in Ni/Yb 2 O 3 /TaN ReRAM cell keeps stable resistance ratio of 10 4 with switching responses over 200 cycles. Good data retention for 10 5 s with sufficient memory window at 85 • C is also demonstrated. The resistance switching dynamic is attributed to the filamentary conduction of oxygen ions/vacancies by electrochemical reaction process in the Yb 2 O 3 switching layer. ExperimentalThe TaN bottom electrode was deposited on SiO 2 /Si substrates by sputter deposition technique. Then, a 30-nm Yb 2 O 3 thin film was deposited on the TaN by radio frequency (rf) magnetron sputtering with an Ar/O 2 atmosphere using a metallic Yb target. The chamber working pressure was maintained at 10 −2 Torr, while the Ar/O 2 flow was set at 3:1 p...

Endurance and Cycle-to-cycle Uniformity Improvement in Tri-Layered CeO2/Ti/CeO2 Resistive Switching Devices by Changing Top Electrode Material

“…Therefore, it can be reasonably concluded that there are sufficient number of defects existing in the device reflecting the concentration of oxygen vacancies. Figure 2(b) shows the XPS trace spectrum in which O 1 s energy state at about 530 eV corresponds to TaON due to nonlattice oxygens29. While, Ta 4p 3/2 peak shows slightly asymmetric shape and binding energy of this peak has been shifted to higher energy as compared to its value for metallic Ta 4p 3/2 (~404 eV) supporting the formation of TaON because of the larger electronegativity of oxygen30.…”

Valence Change Bipolar Resistive Switching Accompanied With Magnetization Switching in CoFe2O4 Thin Film

“…On applying positive bias, at the anode, an electrochemical reaction occurs that separates the oxygen ions from the regular oxygen sites and these oxygen anions can move under the effect of applied electric field which is equivalent to the drift of oxygen vacancies 57 . This electrochemical reaction can be written in Krὅger-vink notations 58 as; where O O represents an oxygen ion on a regular site, O −2 is oxygen anions and V O ++ denotes oxygen vacancies with a double positive charge. If the anode is gold, platinum or another noble metal, it can receive the electrons from the oxygen anions and it may lead to the evolution of oxygen gas and leaves the oxygen vacancies behind 59 ;

Figure 6 Schematic representation of ( a ) Pristine state with top (Al) and bottom (FTO) electrodes, ( b ) Electroforming process, ( c ) Low resistance state with a conducting channel in CFO layer and oxygen diffusion layer near Al electrode, ( d ) Reset process, when oxygen ions are coming back from oxygen diffusion layer to CFO layer, ( e ) and ( f ) High resistance state and Set process.

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Excellent Bipolar Resistive Switching Characteristics of Bi4Ti3O12 Thin Films Prepared via Sol-Gel Process

“…An electrochemical reaction occurs when a forward bias is applied to the top Au electrode of the device. This electrochemical reaction can be written in Krὅger-vink notations as [55]: O represents oxygen ions. The electrochemical reaction separates oxygen ions from the regular oxygen sites, and these oxygen ions can drift under the applied electric field, which is equivalent to the movement of the oxygen vacancy [56].…”