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We report reliable 5 ns switching of spin-transfer torque magnetoresistive random-access memory devices of nominal size 43 nm and a resistance area product of 11 Ω·µm2. We measured 256 devices with a 100% write-error-rate (WER) yield at a WER floor of $10^{-6}$ and a steep WER slope as a function of voltage. A single device had a WER less than $10^{-10}$ for 5 ns write pulses. We show promising 3 ns switching performance, with a 94% WER yield at a $10^{-6}$ WER floor, for 64 devices of nominal size 50 nm.

There have been extensive efforts to improve the properties of conventional metals such as electrical conductivity and rigidity. Here, we report a massive fabrication strategy for metal–carbon nanotube (CNT) laminate-based electrodes. In this method, CNTs were assembled by directed assembly strategy and a thin metal layer was formed by electrodeposition process, and those processes were repeated several times to fabricate multilayered structures. We demonstrated that metal–CNT laminates showed 42% enhancement in the conductivity compared to electrodeposited metals. Furthermore, its Young’s modulus was found to be 88% higher than pure bulk metals. Interestingly, the fabricated structures show I–V characteristics of metal wires while exhibiting typical noise characteristics of CNTs. Since our method uses only conventional microfabrication facilities, it can be readily used by the present microfabrication industry.

We report on the dependence of resonant response to applied tensile stress in Al and Al-CNT (carbon nanotube) nanolaminate thin-film nanomechanical beam resonators. We optically measure the dynamic flexural response, while a chip-bending method is utilized to apply a static tension along its axis. For Al thin-film resonators, large and reversible increases in the resonant frequencies are observed along with near doubling of the resonator quality factor; while, for Al-CNT, largely unaffected with a slight decrease in resonant frequencies. Such behavior gives an insight on the role of CNT as a structural reinforcement in the Al thin-film based nanolaminate.

Composites with added carbon nanotubes are known for their improved mechanical strength. Laminates of thin films of aluminium and carbon nanotubes are now used for the fabrication of micromechanical resonators with significantly enhanced mechanical properties. At micro- and nanoscales, materials with high Young’s moduli and low densities are of great interest for high-frequency micromechanical resonator devices1,2,3,4,5,6,7,8. Incorporating carbon nanotubes (CNTs), with their unmatched properties, has added functionality to many man-made composites9,10,11. We report on the fabrication of ≤100-nm-thick laminates by sputter-deposition of aluminium onto a two-dimensional single-walled CNT network12,13. These nanolaminates—composed of Al, its native oxide Al2O3 and CNTs—are fashioned, in a scalable manner, into suspended doubly clamped micromechanical beams. Dynamic flexural measurements show marked increases in resonant frequencies for nanolaminates with Al–CNT laminae. Such increases, further supported by quasi-static flexural measurements, are partly attributable to enhancements in elastic properties arising from the addition of CNTs. As a consequence, these nanolaminate micromechanical resonators show significant suppression of mechanical nonlinearity and enhanced strength, both of which are advantageous for practical applications and analogous to biological nanocomposites, similarly composed of high-aspect-ratio, mechanically superior mineral platelets in a soft protein matrix14.

For the first time, vertically suspended and stretched carbon nanotube network junctions were fabricated in large quantity via the directed assembly strategy using only conventional microfabrication facilities. In this process, surface molecular patterns on the side-wall of the Al structures were utilized to guide the assembly and alignment of carbon nanotubes in the solution. We also performed extensive experimental (electrical and mechanical) analysis and theoretical simulation about the vertically suspended single-walled carbon nanotube network junctions. The junctions exhibited semiconductor-like conductance behavior. Furthermore, we demonstrated gas sensing and electromechanical sensing using these devices.

We investigated the resistance switching (RS) phenomenon in epitaxial NiO (epi-NiO) films by employing different types of top electrodes (TEs). Epi-NiO showed successive bipolar RS when Pt and CaRuO3 (CRO) were used as the TEs, but not when Al and Ti were used. We studied the temperature dependence of the current–voltage (I–V) characteristics for various TEs and resistance states to understand the conduction properties of TE/epi-NiO. Pristine CRO/epi-NiO showed metallic behavior, while pristine Pt/epi-NiO and Al/epi-NiO showed insulating behavior. Pt/epi-NiO and Al/epi-NiO, however, switched to a metallic or non-insulating state after electroforming. Transmission electron microscopy (TEM) images revealed the presence of a distinct stable interfacial AlO x layer in pristine Al/epi-NiO. On the other hand, the interfacial metal oxide layer was indistinguishable in the case of pristine Pt/epi-NiO and CRO/epi-NiO. Our experimental results suggested that epi-NiO has an oxygen defect on its surface and therefore the various TE/epi-NiO interfaces characterized in this study adopt distinctive electrical states. Further, the bipolar RS phenomenon can be explained by the voltage-polarity-dependent movement of oxygen ions near the interface.