Tunable stochastic memristors for energy-efficient encryption and computing.

Information security and computing, two critical technological challenges for post-digital computation, pose opposing requirements - security (encryption) requires a source of unpredictability, while computing generally requires predictability. Each of these contrasting requirements presently necessitates distinct conventional Si-based hardware units with power-hungry overheads. This work demonstrates CuTe/HfO ('CuTeHO') ion-migration-driven memristors that satisfy the contrasting requirements.

High Thermal Conductivity of Submicrometer Aluminum Nitride Thin Films Sputter-Deposited at Low Temperature.

Aluminum nitride (AlN) is one of the few electrically insulating materials with excellent thermal conductivity, but high-quality films typically require exceedingly hot deposition temperatures (>1000 °C). For thermal management applications in dense or high-power integrated circuits, it is important to deposit heat spreaders at low temperatures (<500 °C), without affecting the underlying electronics. Here, we demonstrate 100 nm to 1.

Synaptic Resistor Circuits Based on Al Oxide and Ti Silicide for Concurrent Learning and Signal Processing in Artificial Intelligence Systems.

Neurobiological circuits containing synapses can process signals while learning concurrently in real time. Before an artificial neural network (ANN) can execute a signal-processing program, it must first be programmed by humans or trained with respect to a large and defined data set during learning processes, resulting in significant latency, high power consumption, and poor adaptability to unpredictable changing environments. In this work, a crossbar circuit of synaptic resistors (synstors) is reported, each synstor integrating a Si channel with an Al oxide memory layer and Ti silicide Schottky contacts.

Energy and Space Efficient Parallel Adder Using Molecular Memristors.

A breakthrough in in-memory computing technologies hinges on the development of appropriate material platforms that can overcome their existing limitations, such as larger than optimal footprint and multiple serial computational steps, with potential accumulation of errors. Using a molecular switching element with multiple non-monotonic and deterministic transitions, the device count and the number of computational steps can be substantially reduced. With molecular materials, however, the realization of a reliable and robust platform is an unattained goal for decades.

Novel Program Scheme of Vertical NAND Flash Memory for Reduction of Z-Interference.

Minimizing the variation in threshold voltage () of programmed cells is required to the extreme level for realizing multi-level-cells; as many as even 5 bits per cell recently. In this work, a recent program scheme to write the cells from the top, for instance the 170th layer, to the bottom, the 1st layer, (T-B scheme) in vertical NAND (VNAND) Flash Memory, is investigated to minimize variation by reducing Z-interference. With the aid of Technology Computer Aided Design (TCAD) the Z-Interference for T-B (84 mV) is found to be better than B-T (105 mV).

Promoting Dual Electronic and Ionic Transport in PEDOT by Embedding Carbon Nanotubes for Large Thermoelectric Responses.

Thermoelectric (TE) energy conversion with nontraditional organic materials is promising in wearable electronics and roll-to-roll manufacturing because of mechanical flexibility, lightweight, and easy processing. Although typical organic materials have a benefit of low thermal conductivity that creates a large temperature gradient, relatively small thermopower (or Seebeck coefficient) often requires copious number of TE legs to fabricate practical TE devices. Here, we show that hybrids of poly(3,4-ethylenedioxythiophene)-tosylate (PEDOT-Tos) and carbon nanotubes (CNTs) can produce extremely large thermopower, ∼14 mV/K at room temperature by a chemical reduction.

Morphology dependent catalysis and surface enhanced Raman scattering (SERS) studies using Pd nanostructures in DNA, CTAB and PVA scaffolds.

Palladium nanoparticles (Pd NPs) of three different morphologies viz., nanocubes with cetyltrimethylammonium bromide (CTAB), nanowires with polyvinyl alcohol (PVA) and Pd NPs with deoxyribonucleic acid (DNA) scaffolds were synthesized by UV-irradiation. Catalysis and surface enhanced Raman scattering (SERS) studies were done with the synthesized morphologically distinct Pd nanostructures for the very first time.

Thermal Transport Driven by Extraneous Nanoparticles and Phase Segregation in Nanostructured Mg2(Si,Sn) and Estimation of Optimum Thermoelectric Performance.

Solid solutions of magnesium silicide and magnesium stannide were recently reported to have high thermoelectric figure-of-merits (ZT) due to remarkably low thermal conductivity, which was conjectured to come from phonon scattering by segregated Mg2Si and Mg2Sn phases without detailed study. However, it is essential to identify the main cause for further improving ZT as well as estimating its upper bound. Here we synthesized Mg2(Si,Sn) with nanoparticles and segregated phases, and theoretically analyzed and estimated the thermal conductivity upon segregated fraction and extraneous nanoparticle addition by fitting experimentally obtained thermal conductivity, electrical conductivity, and thermopower.

Thermally Driven Large N-Type Voltage Responses from Hybrids of Carbon Nanotubes and Poly(3,4-ethylenedioxythiophene) with Tetrakis(dimethylamino)ethylene.

Hybrids of carbon nanotubes (CNTs) and poly(3,4-ethylenedioxythiophene) (PEDOT) treated by tetrakis(dimethylamino)ethylene (TDAE) have large n-type voltages in response to temperature differences. The reduced carrier concentration by TDAE reduction and partially percolated CNT networks embedded in the PEDOT matrix result in high thermopower and low thermal conductivity. The high electron mobility in the CNTs helps to minimally reduce the electrical conductivity of the hybrid, resulting in a large figure-of-merit.

Simultaneously improving electrical conductivity and thermopower of polyaniline composites by utilizing carbon nanotubes as high mobility conduits.

Electrical conductivity and thermopower of isotropic materials typically have inversely proportional correlation because both are strongly affected in the opposite way by the electronic carrier concentration. This behavior has been one of the major hurdles in developing high-performance thermoelectrics whose figure-of-merit enhances with large thermopower and high electrical conductivity. Here we report a promising method of simultaneously improving both properties with polyaniline (PANI) composites filled by carbon nanotubes (CNTs).