Cross-Point Resistive Switching Memory and Urea Sensing by Using Annealed GdO_xFilm in IrO_x/GdO_x/W Structure for Biomedical Applications

Abstract

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.

Concept and modelling of memsensors as two terminal devices with enhanced capabilities in neuromorphic engineering

“…A broad variety of materials and sensing signals has been proposed 5–17 . The memristive effect and UV-sensitivity in ZnO nanorods was recently described in detail by Russo et al .…”

“…Since the postulation of the experimental realization of a memristor device in 2008 1 , there has been an increased effort in understanding and modelling memristive (resistive) switching for a broad variety of device classes 2 – 4 . Up to now (2018) an increasing group of concepts for memristive devices with sensing behaviour has been reported, typically based on metal oxide or semiconductor nanostructures with sensing of temperature 5 , (UV)-light 6 – 9 , gases 10 , 11 , magnetic field 7 , mechanical response 12 , biomolecules 13 – 15 or pH 16 , 17 . However, a systematic treatment of the junction between memristive and sensitive devices is still missing.…”

Controlling Conductive Filament and Tributyrin Sensing Using an Optimized Porous Iridium Interfacial Layer in Cu/Ir/TiNxOy/TiN

“…Similarly, a bioanalyte can also be detected using a metal–insulator–metal structure or resistive switching memory can have combined applications for artificial intelligence (AI) in near future. In our previous study, urea with a concentration of 3 × 10 −3 m is detected using a IrO x /GdO x /W cross‐point memory structure . Tributyrin is a short chained triglyceride, which can be used as biomarker for cardiovascular, Alzheimer's, pancreatitis, and diabetes‐related diseases .…”

Modelling and Realization of a Water-Gated Field Effect Transistor (WG-FET) Using 16-nm-Thick Mono-Si Film

“…Label-free electronic sensors utilizing 30-nm-thick single crystalline Si layers have been shown as promising sensors 26 but their usage as transistor or read-out circuit are not considered. Ion-sensitive FETs (ISFETs) 27 – 29 resemble to these devices, however, they are bulk Si devices operating in depletion/inversion modes with large reference electrodes, and SiO 2 , Si 3 N 4 , Al 2 O 3 , Ta 2 O 5 or other types of insulation layers. WG-FETs require simpler fabrication steps compared to these devices.…”