Abstract:The performances of conductive-bridging random access memory (CBRAM) have been reviewed for different switching materials such as chalcogenides, oxides, and bilayers in different structures. The structure consists of an inert electrode and one oxidized electrode of copper (Cu) or silver (Ag). The switching mechanism is the formation/dissolution of a metallic filament in the switching materials under external bias. However, the growth dynamics of the metallic filament in different switching materials are still … Show more
“…Yazdanparast et al [52] reported the 70-nm CF diameter using a Au/Cu 2 O 3 /Au structure at a CC of 10 mA. According to our previous report [3], the CF diameter is approximately 70 nm in a Cu/GeO x /W structure at a CC of >1 mA. A larger diameter of 2 μm using a Pt/CuO/Pt structure was reported by Yasuhara et al [53].…”
Post-metal annealing temperature-dependent forming-free resistive switching memory characteristics, Fowler-Nordheim (F-N) tunneling at low resistance state, and after reset using a new W/WO3/WOx/W structure have been investigated for the first time. Transmission electron microscope image shows a polycrystalline WO3/WOx layer in a device with a size of 150 × 150 nm2. The composition of WO3/WOx is confirmed by X-ray photo-electron spectroscopy. Non-linear bipolar resistive switching characteristics have been simulated using space-charge limited current (SCLC) conduction at low voltage, F-N tunneling at higher voltage regions, and hopping conduction during reset, which is well fitted with experimental current-voltage characteristics. The barrier height at the WOx/W interface for the devices annealed at 500 °C is lower than those of the as-deposited and annealed at 400 °C (0.63 vs. 1.03 eV). An oxygen-vacant conducting filament with a diameter of ~34 nm is formed/ruptured into the WO3/WOx bilayer owing to oxygen ion migration under external bias as well as barrier height changes for high-resistance to low-resistance states. In addition, the switching mechanism including the easy method has been explored through the current-voltage simulation. The devices annealed at 500 °C have a lower operation voltage, lower barrier height, and higher non-linearity factor, which are beneficial for selector-less crossbar memory arrays.
“…Yazdanparast et al [52] reported the 70-nm CF diameter using a Au/Cu 2 O 3 /Au structure at a CC of 10 mA. According to our previous report [3], the CF diameter is approximately 70 nm in a Cu/GeO x /W structure at a CC of >1 mA. A larger diameter of 2 μm using a Pt/CuO/Pt structure was reported by Yasuhara et al [53].…”
Post-metal annealing temperature-dependent forming-free resistive switching memory characteristics, Fowler-Nordheim (F-N) tunneling at low resistance state, and after reset using a new W/WO3/WOx/W structure have been investigated for the first time. Transmission electron microscope image shows a polycrystalline WO3/WOx layer in a device with a size of 150 × 150 nm2. The composition of WO3/WOx is confirmed by X-ray photo-electron spectroscopy. Non-linear bipolar resistive switching characteristics have been simulated using space-charge limited current (SCLC) conduction at low voltage, F-N tunneling at higher voltage regions, and hopping conduction during reset, which is well fitted with experimental current-voltage characteristics. The barrier height at the WOx/W interface for the devices annealed at 500 °C is lower than those of the as-deposited and annealed at 400 °C (0.63 vs. 1.03 eV). An oxygen-vacant conducting filament with a diameter of ~34 nm is formed/ruptured into the WO3/WOx bilayer owing to oxygen ion migration under external bias as well as barrier height changes for high-resistance to low-resistance states. In addition, the switching mechanism including the easy method has been explored through the current-voltage simulation. The devices annealed at 500 °C have a lower operation voltage, lower barrier height, and higher non-linearity factor, which are beneficial for selector-less crossbar memory arrays.
“…[1][2][3][4][5][6] Even different switching materials such as HfO 2 O 3 9 have been reported, however GdO x has been reported a few. [10][11][12][13] To achieve 3D high-density architecture, cross-point memory is one of the best solutions.…”
Resistive switching characteristics and urea sensing have been investigated by using annealed GdO x film in IrO x /GdO x /W cross-point memory for the first time. The annealed GdO x film shows larger polycrystalline grains as compared to as-deposited films, which is observed by high-resolution transmission electron microscope (HRTEM) and X-ray diffraction patterns (XRD). Surface roughness of the GdO x films on W nano-dome is observed by atomic force microscope (AFM). The annealed IrO x /GdO x /W cross-point memory shows resistance ratio of 1000× times higher, multi-level operation with varying current compliance (CC) from 10-300 μA, good non-linearity factor of 8.3, good dc switching cycles of > 1000 at CC of 10 μA, long read endurance of >10 9 cycles with pulse width of 1 μs at higher read voltage of −0.5 V, and high speed operation of 100 ns. Repeatable resistive switching characteristics at low CC of 10 μA and mechanism are due to the electric field enhancement on the W nano-dome simulated by MATLAB, which controls the O 2− ions migration through polycrystalline GdO x grain boundary as well as Schottky barrier height modulation (0.59 vs. 0.39 eV). In addition, the annealed GdO x membrane in electrolyte-insulator-semiconductor (EIS) structure shows higher pH sensitivity than the as-deposited film (53.2 vs. 45.1 mV/pH) and lower drift (1.8 vs. 2.6 mV/hr) as well as lower detection of pH change (0.034). Detection of pH and urea sensing from 6 to 24 mg/dl have been measured by using cross-point memory, and the sensing mechanism is also discussed, which will be very useful for real healthcare unit in near future.
“…Further study is needed to control Cu diffusion as well as filament diameter or RESET current could be controlled. Obviously, if the LRS value is low, then the RESET voltage will be also small; especially RESET voltage for the CBRAM devices is small [1]. A large resistance ratio of >10 5 is observed because of higher RESET current.…”
Section: Resultsmentioning
confidence: 99%
“…Basically, the erase operation can be controlled by external current (> I RESET ) and voltage (< V RESET ). However, the RESET operation will have also high-speed operation of few nanoseconds [1]. So, external light impacts the device switching, which is also very useful for a new area of research.Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Recently, the conductive-bridge resistive-random-access-memory (CBRAM) device is considered among the most promising solutions for future low-cost embedded non-volatile memories [1–5]. Although several solid-electrolyte materials such as GeS 2 [6], GeTe [7], Ag 2 S [8, 9], and GeSe [10–13] have been reported to explore CBRAM performances and switching mechanism, however, light-induced resistive switching phenomena of different materials have been reported few.…”
It is known that conductive-bridge resistive-random-access-memory (CBRAM) device is very important for future high-density nonvolatile memory as well as logic application. Even though the CBRAM devices using different materials, structures, and switching performance have been reported in Nanoscale Res. Lett., 2015, however, optical switching characteristics by using thermally grown Ge0.2Se0.8 film in Cu/GeSex/W structure are reported for the first time in this study. The Cu/GeSex/W memory devices have low current compliances (CCs) ranging from 1 nA to 500 μA with low voltage of ±1.2 V, high resistance ratio of approximately 103, stable endurance of >200 cycles, and good data retention of >7 × 103 s at 85 °C. Multi-steps of RESET phenomena and evolution of Cu filaments’ shape under CCs ranging from 1 nA to 500 μA have been discussed. Under external white-light illumination with an intensity of 2.68 mW/cm2 (wavelength ranges from 390 to 700 nm), memory device shows optical switching with long read pulse endurance of >105 cycles. This CBRAM device has optically programmed and electrically erased, which can open up a new area of research field for future application.
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