ABSTRACT
Antimicrobial textiles (65% cotton – 35% polyester) were functionalized using a patented technology that combines an antimicrobial molecule – polyhexamethylene biguanide (PHMB) and a ...precipitating agent – sodium laurylsulphate. Surface characterization was performed by x‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry, and both techniques made clear signatures of PHMB at the top surface of treated textiles. Washing led to a strong decrease of PHMB concentration at the surface. Comparison of textile surface analysis and antimicrobial tests indicated that the amount of PHMB at its extreme surface of textiles after five or 10 industrial washings was sufficient to inhibit Listeria innocua but not Pseudomonas aeruginosa growth. The viability of L. innocua cells after contact with PHMB‐treated textile after one industrial washing was estimated using the Live/Dead BacLight kit (Molecular Probes, Eugene, OR): the combination of epifluorescence microscopy observations coupled with classic enumeration allowed detection of the presence of viable but nonculturable cells.
PRACTICAL APPLICATIONS
Protective clothing is required in the food‐processing industry to protect products from being contaminated by microorganisms carried by workers' clothes or filtration systems. Consequently, there is an increasing interest in the use of antimicrobial functionalized textiles in the food industry to avoid that textiles could be vectors for pathogenic or food spoilage microorganisms. In the present study, the correlation between PHMB (the antimicrobial agent) at the surface of textiles (monitored by surface analysis characterization methods) and their antibacterial activity was assessed. After contact with antimicrobial textiles, the enumeration of bacteria was performed either by plate counting or by direct observation by epifluorescence microscopy in the presence of fluorescent viability markers in order to determine whether viable but nonculturable bacterial cells were present.
•We analyzed the charge pumping signals in ultra-scaled 3D vertical devices.•Statistical analysis has been used to characteristic the variability of poly-Si channel.•The quality of bottom and top ...junctions with different process has been presented.•Different poly-Si formations and hole sizes have been investigated.•Different annealing conditions have been carried out for optimization of the channel of 3D flash memory.
Poly silicon has been used as the vertical channel material in 3D devices for future generations of NAND flash memory. Improving the read current and reducing its variations in the small-sized single-hole structure are among the critical challenges, which require understanding and characterizing interface states and bulk defects in the vertical 3D poly-Si channel. In this paper, we analyzed the charge pumping signals in ultra-scaled 3D vertical devices and characterized the poly-Si channel by using statistical analysis. Devices with different poly-Si formations, hole sizes and annealing conditions have been investigated, in order to optimize the 3D device.
In this work we have studied soft breakdown (SBD) in capacitors and nMOSFET's with 4.5-nm oxide thickness. It is shown that for larger area devices gate current and substrate current as a function of ...the gate voltage after SBD are stable and unique curves, but for smaller area devices both currents become lower and unstable. This difference can be explained by the different energy available for discharging in the SBD path. It is shown that the SBD detection strongly depends on the test structure area. In nMOSFET's for positive gate polarity, the large increase in the substrate current at the SBD moment is proposed as a sensitive SBD detector. Two level fluctuations in the gate current are investigated at different voltages and are explained by means of a model where electron capture-emission in the traps of the SBD path induces local field fluctuations causing variations in the tunneling rate across the oxide. In the substrate current directly correlated two-level fluctuations are observed.
Improving the efficiency of the purchasing process provides important opportunities to increase a firm's profitability. In this paper we introduce a mathematical programming model that uses total ...cost of ownership information to simultaneously select suppliers and determine order quantities over a multi-period time horizon. The total cost of ownership quantifies all costs associated with the purchasing process and is based on the activities and cost drivers determined by an activity based costing system. Our approach is motivated by the purchasing problem of heating electrodes at Cockerill Sambre, a Belgian multinational steel producer. In this case quality issues account for more than 70% of the total cost of ownership making the quality of a supplier a critical success factor in the supplier selection process.
Oxide breakdown has been proposed to be a limiting factor for future generation CMOS. The breakdown is caused by defect generation in the oxide. Although electron trap generation has received much ...attention, there is little information available on the hole trap generation. The relatively high potential barrier for holes at the oxide/Si interface makes it difficult to achieve a high level of hole injection. Most previous work was limited to an injection level Q/sub inj/ of 10/sup 14/ cm/sup -2/. In this paper, we investigate the hole trapping and trap generation when Q/sub inj/ reaches the order of 10/sup 18/ cm/sup -2/. When Q/sub inj/<10/sup 15/ cm/sup -2/, the trapping is dominated by the as-grown traps. As Q/sub inj/ increases further, however, it is found that the generation of new traps controls the trapping. The trap generation does not saturate up to the oxide breakdown. The trapping kinetics for both the as-grown and the generated traps is studied. The relationship between the density of generated traps and the Q/sub inj/ is explored. Attention is paid to how the trapping and trap generation depends on the distance from the interface. In contrast to the uniform generation of electron traps across the oxide, we found that the hole trap generation was not uniform and it moved away from the interface as Q/sub inj/ increased.
After studying the properties of hole traps in Part I, attention is turned to the physical processes responsible for generating hole traps in Part II of this work. The applicability of four models to ...hole-trap creation will be examined. These are the trapped hole-electron recombination model, the electrical field energy model, the hole injection model, and the hydrogen model. To testify these models, stresses have to be carried out not only under substrate hole injection (SHI), but also under Fowler-Nordheim injection (FNI). By combining FNI with SHI, we will be able to control hole fluency independent of the electron-induced hydrogen release. This allows us to determine how important hydrogen is for hole-trap generation. Although it was reported that hydrogen could play a major role in positive charge generation for devices with an Al gate or without a gate, we will show that hydrogen does not dominate hole-trap generation, when poly-si gated devices are stressed under our test conditions. Unambiguous results will also be given to show that key predictions of the recombination model and the electrical field energy model are not observed here. In this paper, the most important process for hole-trap generation is found to be the direct interaction of injected holes with the oxide.
As the downscaling of gate oxides continues, trap density in the oxide bulk will reduce, but positive charges formed near to the SiO/sub 2//Si interface become relatively important. For gate oxides ...used in industry, hole trapping is the most important process for positive charge formation. Apart from as-grown hole traps, we recently reported that new hole traps were generated by electrical stresses. Information on these hole traps, however, is still limited. In part I of this work, properties of both generated and as-grown hole traps are investigated. For the first time, it will be clearly shown that generated hole traps consist of two components; cyclic positive charges (CPC) and antineutralization positive charges (ANPC). The charging and discharging rates of CPC are similar, while the neutralization of ANPC is much more difficult than its charging. Differences between them are also observed in generation kinetics and dependence on measurement temperature. Efforts will be made to explain their differences in terms of energy levels and to link them with positive charges reported in earlier works. We will also show that as-grown traps, regardless their distance from the interface, are not responsible for either ANPC or CPC. This is to say that generated hole traps are not the same as as-grown traps and their differences will be highlighted. In part II, hole trap generation mechanisms will be investigated.
•Random telegraph noise and low-frequency noise in polysilicon device.•The impact of electron trapping and detrapping events in scaled non-volatile memories.•Behavior of gate oxide, interface and ...polysilicon traps in n-type polysilicon cylindrical vertical transistors.
In this work the drain current random telegraph noise (RTN) in polysilicon-channel cylindrical vertical FET structures is studied experimentally. We show that single electron trapping events can induce significant drain current fluctuations during read operation in deeply scaled non-volatile memories (NVMs). Low-frequency (LF) noise and capture and emission time constants of the traps are also analyzed at different gate and drain bias conditions. Two independent types of traps are identified in this study, which we categorize as slow and fast states. In this paper, we show that the RTN most likely originates from traps in the highly defective channel region, in addition to the fluctuations caused by defects in the oxide close to the interface with the channel.
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