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We report on proton radiation effects on Si-nanocrystal (Si-NCs) MOS capacitors and nMOS transistors aiming at non-volatile memory applications. Irradiation experiments were conducted on NC MOS capacitors using protons of 1.5 MeV and 6.5 MeV and on NC nMOS transistors using protons of 1.5 MeV. The range of doses investigated was ~ 1 to ~ 100 Mrad(Si[O.sub.2]). A 2-D layer of Si NCs with ~ 3 nm mean diameter and [10.sup.12] [cm.sup.-2] surface density was successfully achieved by low-energy (1 keV) ion-beam-synthesis in thin Si[O.sub.2] layers. After irradiation, programmed capacitors are found to undergo bit flip while programmed transistors are not. Charge retention measurements at room temperature for the write and erase states of irradiated and non-irradiated samples reveal that a significant memory window exists at an extrapolated time of ten years even after an irradiation dose as high as 120 Mrad (Si[O.sub.2]). The flat-band decay rate of the erase state in NC MOS capacitors does not depend on the irradiation-dose while the opposite occurs for the write state which is found to be directly dependent on [D.sub.it] values after irradiation. These results clearly indicate that NC Non-Volatile Memories (NVM) are promising radiation tolerant devices. Index Terms--Data retention, nanocrystal memories, nonvolatile memory (NVM), proton radiation effects.

Abstract: In this work we investigate CO2 laser annealing at millisecond time scale for the fabrication of Ultra Shallow Junctions, able to fulfill the requirements imposed for sub-45nm CMOS nodes. Silicon samples doped with Boron using BF3 plasma implantation technique at low energy (0.4 and 0.6keV) were used to ensure ultra shallow as implanted boron concentration profiles. Our aim is to achieve high electrical activation level of the dopant, while maintaining the Boron concentration profile as immobile as possible. Samples have been irradiated at a variety of annealing conditions regarding the duration of the irradiation and the power density; however, in every case the peak surface temperature was kept in the range of 1080–1320°C. Sheet resistance measurements indicate significant enhancement in the activation levels, while chemical characterization by means of SIMS, shows very limited movement of the dopant concentration profile, especially for short pulse duration conditions. [Copyright &y& Elsevier]

The coupling between sub-bandgap defect states and surface plasmon resonances in Au nanoparticles and its effects on the photoconductivity performance of TiO 2 are investigated in both the ultraviolet (UV) and visible spectrum. Incorporating a 2 nm gold nanoparticle layer in the photodetector device architecture creates additional trapping pathways, resulting in a faster current decay under UV illumination and a significant enhancement in the visible photocurrent of TiO 2 , with an 8-fold enhancement of the defects-related photocurrent. We show that hot electron injection (HEI) and plasmonic resonance energy transfer (PRET) jointly contribute to the observed photoconductivity enhancement. In addition to shedding light on the below-band-edge photoconductivity of TiO 2 , our work provides insight into new methods to probe and examine the surface defects of metal oxide semiconductors using plasmonic resonances., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

We report the fabrication of a solution-processed n-type Thin Film Transistor (TFT) with current on/off ratios of 10 4 , a turn-on voltage ( V ON ) of 1.2 V and a threshold voltage ( V T ) of 6.2 V. The TFT incorporates an insoluble and intractable dielectric layer ( k = 7-9) prepared in situ from solution-processed and then photopolymerised ligand-stabilised, inorganic/organic TiO 2 nanorods. A solution processed zinc oxide (ZnO) layer acts as the semiconductor. The new surface-modified TiO 2 nanorods were synthesised using a ligand replacement process with a monolayer coating of photopolymerisable 10-undecynylphosphonic acid (10UCYPA) to render them both soluble in common organic solvents and be photopolymerisable using UV-illumination after having been deposited on substrate surfaces from solution and drying., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A significant impediment to the use of impedance spectroscopy in bio-sensing is the electrode polarization effect that arises from the movement of free ions to the electrode-solution interface, forming an electrical double layer (EDL). The EDL screens the dielectric response of the bulk and its large capacitance dominates the signal response at low frequency, masking information particularly relevant for biological samples, such as molecular conformation changes and DNA hybridization. The fabrication of nanogap capacitors with electrode separation less than the EDL thickness can significantly reduce electrode polarization effects and provide enormous improvement in sensitivity due to better matching of the sensing volume with the size of the target entities. We report on the fabrication of a horizontal thin-film nanogap capacitive sensor with electrode separation of 40 nm that shows almost no electrode polarization effects when measured with water and ionic buffer solutions, thereby allowing direct quantification of their relative permittivity at low frequencies. Surface modification of the electrodes with thiol-functionalized single strand DNA aptamers transforms the device into a label-free biosensor with high sensitivity and selectivity towards the detection of a specific protein. Using this approach, we have developed a biosensor for the detection of human alpha thrombin. In addition, we also examine frequency dependent permittivity measurements on high ionic strength solutions contained within the nanogap and discuss how these support recent experimental observations of large Debye lengths. A large shift in the Debye relaxation frequency to lower frequency is also found, which is consistent with water molecules being in a rigid-like state, possibly indicating the formation of an ordered "ice-like" phase. Altogether, this work highlights the need for better understanding of fluids in confined, nanoscale geometries, from which important new applications in sensing may arise.

We report the synthesis of the first stable, solution-processable and photocrosslinkable hybrid organic/inorganic titanium dioxide nanorods as 'hairy rods' coated with phosphonate ligands with photoreactive coumarin groups located in a terminal position. The relationships between the chemical structure of the diethyl-ω-[(7-oxycoumaryl)- n -alkyl]phosphonate ligands on the ligand exchange rate (LER) and the solubility of the resultant ligand-stabilized titanium dioxide nanorods in organic solvents are elucidated. These TiO 2 nanorods, with an organic ligand coating, are short enough (aspect ratio = 5-8) to be dissolved in chlorobenzene at high concentrations, but long enough to form lyotropic nematic liquid crystals. These colloidal solutions are used to deposit a thin, uniform layer of hybrid organic/inorganic TiO 2 nanorods with their long axes in the plane of a flat, smooth substrate through a self-organization process. Standard photolithographic patterning creates an insoluble dielectric layer of the desired thickness, smoothness and uniformity and with a dielectric constant of sufficient magnitude, k = 8, suitable for the fabrication of multilayer, plastic electronic devices using solution-based fabrication techniques, such as ink-jet printing, used in roll-to-roll manufacturing., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Optical control of memristors opens the route to new applications in optoelectronic switching and neuromorphic computing. Motivated by the need for reversible and latched optical switching we report on the development of a memristor with electronic properties tunable and switchable by wavelength and polarization specific light. The device consists of an optically active azobenzene polymer, poly(disperse red 1 acrylate), overlaying a forest of vertically aligned ZnO nanorods. Illumination induces trans-cis isomerization of the azobenzene molecules, which expands or contracts the polymer layer and alters the resistance of the off/on states, their ratio and retention time. The reversible optical effect enables dynamic control of a memristor's learning properties including control of synaptic potentiation and depression, optical switching between short-term and long-term memory and optical modulation of the synaptic efficacy via spike timing dependent plasticity. The work opens the route to the dynamic patterning of memristor networks both spatially and temporally by light, thus allowing the development of new optically reconfigurable neural networks and adaptive electronic circuits.

Narrow-band photoconductivity with a spectral width of 0.16 eV is obtained from solution-processed colloidal ZnO nanocrystals beneath the band-edge at 2.25 eV. A new model involving electron transfer from deep defects to discrete shallow donors is introduced to explain the narrow spectrum and the exponential form of the current rise and decay transients. The defects are tentatively assigned to neutral oxygen vacancies. The photocurrent responsivity can be enhanced by storage in air, and this correlates with the formation of carbonate surface species by capture of carbon dioxide during storage. This controllability is exploited to develop a low-cost and scalable photolithographic approach to pixelate photodetectors for applications such as object discrimination, sensing, etc. The spectral response can be spatially patterned so that dual (ultraviolet and green) and single (ultraviolet only) wavelength detecting ZnO pixels can be produced on the same substrate. This presents a new sensor mode with applications in security or full color imaging.

Surface interface engineering using superhydrophobic gold electrodes made with 1-dodecanethiol self-assembled monolayer (SAM) has been used to enhance the current limiting properties of novel surge protection devices based on the intrinsic conducting polymer, polyaniline doped with methanesulfonic acid. The resulting devices show significantly enhanced current limiting characteristics, including current saturation, foldback, and negative differential effects. We show how SAM modification changes the morphology of the polymer film directly adjacent to the electrodes, leading to the formation of an interfacial compact thin film that lowers the contact resistance at the Au-polymer interface. We attribute the enhanced current limiting properties of the devices to a combination of lower contact resistance and increased Joule heating within this interface region which during a current surge produces a current blocking resistive barrier due to a thermally induced dedoping effect caused by the rapid diffusion of moisture away from this region. The effect is exacerbated at higher applied voltages as the higher temperature leads to stronger depletion of charge carriers in this region, resulting in a negative differential resistance effect.