Formation polarity dependent improved resistive switching memory characteristics using nanoscale (1.3 nm) core-shell IrOx nano-dots

Abstract

Improved resistive switching memory characteristics by controlling the formation polarity in an IrOx/Al2O3/IrOx-ND/Al2O3/WOx/W structure have been investigated. High density of 1 × 1013/cm2 and small size of 1.3 nm in diameter of the IrOx nano-dots (NDs) have been observed by high-resolution transmission electron microscopy. The IrOx-NDs, Al2O3, and WOx layers are confirmed by X-ray photo-electron spectroscopy. Capacitance-voltage hysteresis characteristics show higher charge-trapping density in the IrOx-ND memory as compared to the pure Al2O3 devices. This suggests that the IrOx-ND device has more defect sites than that of the pure Al2O3 devices. Stable resistive switching characteristics under positive formation polarity on the IrOx electrode are observed, and the conducting filament is controlled by oxygen ion migration toward the Al2O3/IrOx top electrode interface. The switching mechanism is explained schematically based on our resistive switching parameters. The resistive switching random access memory (ReRAM) devices under positive formation polarity have an applicable resistance ratio of > 10 after extrapolation of 10 years data retention at 85°C and a long read endurance of 105 cycles. A large memory size of > 60 Tbit/sq in. can be realized in future for ReRAM device application. This study is not only important for improving the resistive switching memory performance but also help design other nanoscale high-density nonvolatile memory in future.

Resistive switching memory characteristics of Ge/GeO x nanowires and evidence of oxygen ion migration

“…In recent years, many solid electrolyte materials such as Ge x Se 1 − x [9-12], GeS 2 [13], Ta 2 O 5 [14], Ag 2 S [15,16], ZrO 2 [17], TiO x /ZrO 2 [18], GeSe x /TaO x [19], HfO 2 [20], CuTe/Al 2 O 3 [21], and Ti/TaO x [22] have been used in conductive bridging random access memory (CBRAM) applications. RRAM devices containing materials such as HfO x [5,6], SrTiO 3 [7], TiO 2 [8,23], ZrO 2 [24,25], Na 0.5 Bi 0.5 TiO 3 [26], NiO x [27], ZnO [28,29], TaO x [30,31], and AlO x [32,33] have been reported. However, GeO x has only been used in RRAM as Ni/GeO x /SrTiO x /TaN [34] and Cu/GeO x /W [35] structures and in Ge-doped HfO 2 films [36].…”

Multilevel unipolar resistive switching with negative differential resistance effect in Ag/SiO2/Pt device

“…[8][9][10][11][12][13][14] Similar abnormal unipolar RS phenomenon was also observed in other RRAM systems with embedded nanocrystals, which typically exhibits good uniformity and multilevel storage potential. [15][16][17][18][19][20][21] However, a very large electroforming voltage is required to form the Si nanocrystal chain in SiO x , leading to the degradation of the device reliability and the increase of the complexity of peripheral circuit.…”

Dual operation characteristics of resistance random access memory in indium-gallium-zinc-oxide thin film transistors

“…formed at the interface of the source electrode and IGZO. 27,28 Furthermore, the contact between source electrode and a-IGZO film is separated due to this oxygen migration, as shown in Figs. 2…”