When the pristine resistive memory device is formed using positive polarity bias on the TE, it is termed as PF, while the negative voltage-formed device is termed selleck chemicals as an NF device. PF devices with similar switching behavior are obtained using different high-κ oxide films of AlOx,
GdOx, HfOx, and TaOx. The switching mechanism is the formation/oxidation of oxygen vacancies in a conducting filament by controlling the migration of oxygen ions through the electrically formed interfacial layer. This unique phenomenon helps to design high-density cross-point memory using an IrOx/AlOx/W structure. This cross-point memory was forming-free, exhibiting 1,000 consecutive ‘dc’ cycles at a current compliance (CC) of <200 μA and a small operation voltage of ±2 V, highly uniform switching (yield >95%) with multilevel capability (at least four different levels of low resistance state (LRS)). The device can be switched even using a very small current of 10 μA, which makes it useful for low power applications. The surface
morphology and roughness of the structure were observed by atomic force microscopy (AFM). The device size and interfaces of layers were investigated by transmission P505-15 cell line electron microscopy (TEM). These observations show that the improved performance of this device structure can be attributed to the electrically formed O-rich NVP-BSK805 mw interfacial layer at the top electrode/filament interface. The devices have also shown good read endurance of >105 cycles and data retention at 85°C under a
low CC of 50 μA. Methods Resistive switching memory devices using high-κ oxides AlOx, GdOx, HfOx, and TaOx in a standard via-hole IrOx/high-κx/W structure (Device: S1) were fabricated. A W layer with a thickness of approximately 100 nm as a bottom electrode (BE) was deposited on SiO2 (200 nm)/Si substrates. Figure 1 shows an AFM image taken in tapping mode using an Innova Scanning Probe Microscope system (Bruker, Madison, WI, USA) of a deposited W film surface. The average and root mean square (RMS) roughness of the surface were 0.91 and 1.18 nm, respectively. An SiO2 layer with a thickness of approximately 150 MYO10 nm was then deposited at low temperature on each W BE. Photolithography and dry etching techniques were used to form holes of different sizes in the range of 0.4 to 8 μm in the structure. Then, AlOx and HfOx films were deposited by sputtering, and GdOx and TaOx films were deposited by electron beam evaporation. The thickness of each high-κ film was 10 to 15 nm. The top electrode (TE) of IrOx(approximately 200 nm thick) was deposited by reactive sputtering using a pure Ir target and O2 as the reactive gas. The final devices with a structure of IrOx/high-κx/W were obtained after a lift-off process. The structure of the memory devices and thicknesses of all deposited layers were observed by TEM at an energy of 200 keV.