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Al2O3 is used to form Al2O3/GaN and Al2O3/Si heterostructures for many electronic and optoelectronic devices. Yet the origins of the positive interfacial charges in the Al2O3/GaN heterostructure and negative interfacial charges in the Al2O3/Si heterostructure are often elusive. Herein, in‐depth studies of the Al2O3/GaN and Al2O3/Si heterostructures are conducted, especially on how the atomic coordination structure affects the interfacial charges. It is discovered that the octahedral [AlO6]9− coordination surpassed tetrahedral [AlO4]5− coordination at the Al2O3/GaN interface, whereas tetrahedral [AlO4]5− coordination dominated at the Al2O3/Si interface. Therefore, the interfacial charge polarity is correlated with the nonstoichiometry atomic coordination of Al2O3 at the two interfaces. This study reveals the atomic origin of charge polarity at high‐k/semiconductor interfaces and could facilitate the development of high‐performance optoelectronic and electronic devices through engineering the atomic coordination structure of the high‐k materials. [ABSTRACT FROM AUTHOR]

Nanofiltration (NF) is commonly recognized as one of the effective technologies for the separation of magnesium (Mg2+) and lithium (Li+) from salt-lake brines. Charge repulsion and size exclusion effects often play an important role, whose functions primarily occur at the top surface and the matrix, respectively, of the skin layer. In this study, a novel nanofiltration (NF) membrane is prepared that integrates both size exclusion and charge repulsion effects into the matrix of the skin layer for enhanced Mg2+/Li+ separation. With the surface-modified hydrophilic polyethylene (PE) membrane as the supporting layer, the prepared NF membrane successfully incorporated Fe3+ ions into the matrix of the skin layer during the interfacial polymerization (IP). Fe3+ ions which chelate with amine groups of PEI (aqueous-phase monomers during IP) ensure abundant positive charges within the matrix of the skin layer, providing good hydrophilicity and sustained electrostatic repulsive force against the transmembrane transport of Mg2+, and thus the enhanced rejection. Results exhibited a remarkable 92.6 % rejection rate for MgCl 2 and a higher water permeance of 22 LMH/bar, which is 1.57 times greater than that of the traditional PEI-TMC membranes. The nanofiltration process effectively reduced the Mg2+/Li+ ratio from 50 in the feed to 5.4 in the permeate solution. It is also interesting to find that although the pore size of the skin layer (0.53 nm in radius) exceeds both the hydrated radii of Mg2+ and Li+, the positive charges within the matrix of the skin layer still provide good selective separation performance, thus effectively breaking the trade-off of permeability and selectivity. This study offers a fresh perspective on the preparation of nanofiltration membranes by systematically exploring the potential of integration of charge repulsion and size exclusion effects into one location, i.e., the matrix of the skin layer for enhanced Mg2+/Li+ separation performance. [Display omitted] • Integration of size exclusion and charge repulsion into the skin layer matrix of NF membranes. • Continuous repulsive force offered by Fe3+ against the transmembrane transport of Mg2+. • High permeance (22 LMH/bar) with remarkable 92.6 % rejection despite of larger pore size. • Stable 72-h NF performance with Mg2+/Li+ ratio decreasing from 50 (feed) to 5.4 (permeate). • Break of trade-off between permeability and selectivity by the positive charges in skin layer matrix. [ABSTRACT FROM AUTHOR]

Low-power circuits are important for many applications, such as Internet of Things. Device variations and fluctuations are challenging their design. Random telegraph noise (RTN) is an important source of fluctuation. To verify a design by simulation, one needs assessing the impact of fluctuation in both driving current $\Delta {I}_{d}$ and threshold voltage $\Delta {V}_{\textsf {th}}$. Many early works, however, only measured RTN-induced $\Delta {I}_{d}$. $\Delta {V}_{\textsf {th}}$ was not directly measured because of two difficulties: its average value is low and it is highly dynamic. Early works often estimated $\Delta {V}_{\textsf {th}}$ from $\Delta {I}_{d}/{g}_{m}$ (${V}_{g} = {V}_{\textit {dd}}$), where ${g}_{m}$ is the transconductance, without giving its accuracy. The objective of this paper is to develop a new Trigger-When-Charged (TWC) technique for directly measuring the RTN-induced $\Delta {V}_{\textsf {th}}$. By triggering the measurement only when a trap is charged, measurement accuracy is substantially improved. It is found that there is a poor correlation between $\Delta {I}_{d}/{g}_{m}$ (${V}_{g} = {V}_{\textit {dd}}$) and the directly measured $\Delta {V}_{\textsf {th}}$ (${V}_{g} = {V}_{\textsf {th}}$). The former is twice of the latter on average. The origin for this difference is analyzed. For the first time, the TWC is applied to evaluate device-to-device variations of the directly measured RTN-induced $\Delta {V}_{\textsf {th}}$ without selecting devices. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The charges converged on the surface of KNN by polarization. • KNN with piezoelectric constant of 80 pC/N achieved almost 100% antibacterial rate. • The antibacterial effect and biocompatibility were positive charges-dependent. Abstract The implant infection is one of the most serious postsurgical complications of medical device implantation. Therefore, the development of biocompatible materials with improved antibacterial properties is of great importance. It might be a new insight to apply the intrinsic electrical properties of biomaterials to solve this problem. Here, potassium-sodium niobate piezoceramics (K 0.5 Na 0.5 NbO 3 , KNN) with different piezoelectric constants were prepared, and the microstructures and piezoelectric properties of these piezoceramics were evaluated. Moreover, the antibacterial effect and biocompatibility of these piezoceramics were assayed. Results showed that these piezoceramics were able to decrease the colonies of bacteria staphylococcus aureus (S. aureus), favor the rat bone marrow mesenchymal stem cells (rBMSCs) proliferation and promote the cell adhesion and spreading. The above effects were found closely related to the surface positive charges of the piezoceramics, and the sample bearing the most positive charges on its surface (sample 80KNN) had the best performance in both antibacterial effect and biocompatibility. Based on our work, it is feasible to develop biocompatible antibacterial materials by controlling piezoelectric properties. [ABSTRACT FROM AUTHOR]

To predict the negative bias temperature instability (NBTI) toward the end of pMOSFETs’ ten years lifetime, power-law-based extrapolation is the industrial standard method. The prediction accuracy crucially depends on the accuracy of time exponents, n. n reported by early work spreads in a wide range and varies with measurement conditions, which can lead to unacceptable errors when extrapolated to ten years. The objective of this paper is to find how to make n extraction independent of measurement conditions. After removing the contribution from as-grown hole traps, a new method is proposed to capture the generated defects (GDs) in their entirety. n extracted by this method is around 0.2 and insensitive to measurement conditions for the four fabrication processes we tested. The model based on this method is verified by comparing its prediction with measurements. Under ac operation, the model predicts that the GD can contribute to ~90% of NBTI at ten years. [ABSTRACT FROM PUBLISHER]

The high mobility germanium (Ge) channel is considered as a strong candidate for replacing Si in pMOSFETs in the near future. It has been reported that the conventional power-law degradation kinetics of Si devices is inapplicable to Ge. In this paper, further investigation is carried out on defect energy distribution, which clearly shows that this is because the defects in GeO2/Ge and SiON/Si devices have different physical properties. The three main differences are: 1) energy alternating defects (EAD) exist in Ge devices but are insignificant in Si; 2) the distribution of as-grown hole traps has a tail in the Ge bandgap but not in Si, which plays an important role in the degradation kinetics and device lifetime prediction; and 3) EAD generation in Ge devices requires the injected charge carriers to overcome a second energy barrier, but not in Si. Taking the above differences into account, the power-law kinetics of EAD generation can be successfully restored by following a new procedure, which can assist in the Ge process/device optimization. [ABSTRACT FROM PUBLISHER]

A novel positively charged loose nanofiltration (NF) membrane was fabricated feasibly by UV-induced photografting polymerization of diallyl dimethyl ammonium chloride (DADMAC) on Polysulfone ultrafiltration membrane. A possible reaction mechanism was proposed that a linear chain structure and/or pyrrole like five-membered nitrogen heterocycles structure on the side chain were grafted to form the active barrier layer. NF membrane demonstrated a looser average pore size of 8.6 nm and positive charges surface. Owing to the nanoscale ultrathin nanoscale barrier layer and the combination of Donnan exclusion and steric hindrance, NF membrane exhibited good hydrophilicity, a high pure flux of 60 L/m 2 h (0.5 MPa), a good salt rejection to Mg 2+ (90.8%), Al 3+ (94.0%), Ca 2+ (91.5%), and a high dye rejection to methylene blue (99.4%) and congo red (100.0%) respectively. The salts rejection of NF membrane to different salts followed the order of AlCl 3 > CaCl 2 > MgCl 2 > NaCl > LiCl > MgSO 4 > Na 2 SO 4. NF membrane showed certain fouling resistance to seawater and BSA solution. The grafting polymerization kinetics were comprehensively investigated including irradiation time, monomer concentration and irradiation intensity. X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurement were employed to investigate membrane chemistry, morphologies, and hydrophilicity. [ABSTRACT FROM AUTHOR]

A probing technique to obtain the energy distribution of positive charges in high-k gate stack dielectrics, both within and beyond the substrate bandgap, has been proposed. The energy distribution of different high-k devices has been investigated and attention has been paid to their differences from the single-layered SiON devices. The results obtained from the technique demonstrate the existence of different types of positive charges with each type of them dominating a different energy region. It is observed that the positive charges in high-k stacks are dominated by the as-grown hole traps below the valence band and the cyclic positive charges within the bandgap. The increase in the cyclic positive charges in thinner high-k devices suggests higher NBTI for future CMOS technologies. It is also observed from the energy profile that the metal gate can impact the NBTI substantially. The energy profile obtained from this technique clearly indicates that process optimization is essential for minimizing NBTI in the high-k gate stacks. [ABSTRACT FROM AUTHOR]

Positive charges (PCs) in gate dielectric shift the threshold voltage and cause a time-dependent device variability. To assess their impact on circuits, it is useful to know their distribution for a wide energy range both within and beyond silicon bandgap. Such a distribution is still missing, and a technique for its extraction has not been demonstrated yet. The central objective of this paper is, for the first time, to develop a new fast technique and to demonstrate its capability for probing the energy distribution of PCs over such a wide energy range. Results show that PCs can vary significantly with energy level. The PCs in different energy regions clearly originate from different defects. The PCs below the valence band edge are as-grown hole traps that are insensitive to stress time and temperature, and substantially higher in thermal SiON. The PCs above the valence-band edge are from created defects. The PCs within the bandgap have a peak near Ev + 0.8 eV and saturate for either longer stress time or higher stress temperature. In contrast, the PCs above a conduction band edge, namely the antineutralization positive charges, do not saturate, and their generation is clearly thermally accelerated. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a review on the recent progress in understanding defects and instabilities in Hf-dielectric/SiON stacks will be given for both nMOSFETs and pMOSFETs. The key issues addressed for nMOSFETs include the capture cross section of electron traps, their location and justification of the model used. For pMOSFETs, a framework will be proposed for the defects and then used to interpret the anomalous NBTI kinetics. The dominant dielectric layer for positive charging will be identified. Wherever possible, the classical SiO2 will be used as a benchmark and the similarity and difference between the stack and SiO2 will be highlighted. It will be shown that the stack behaves like a degraded SiO2. [Copyright &y& Elsevier]

Positive charges in Hf-based gate stacks play an important role in the negative bias temperature instability of pMOSFETs, and their suppression is a pressing issue. The loca- tion of positive charges is not clear, and central to this letter is determining which layer of the stack dominates positive charging. The results clearly show that positive charges are dominated by the interfacial layer (IL) and that they do not pile up at the HfSiONIIL interface. The results support the assumption that positive charges are located close to the IL/substrate interface. Unlike electron trapping that reduces rapidly for thinner Hf dielectric layer, posi. tive charges cannot be reduced by using a thinner HfSiON film. Index Ternzs-Hf silicates, high-k gate dielectric, instability, negative bias temperature instability (NBTI), positive charges, reliability, spatial distribution. [ABSTRACT FROM AUTHOR]

A Hf-based dielectric has been selected to replace SiON for CMOS technologies. When compared with SiON, Hf dielectrics can suffer from higher instability. Previous attentions were focused on electron trapping, and positive charging received less attention. The objective of this paper is to study the impact of positive charging on device performance and to provide a framework for the defect. Three components of threshold voltage instability ΔVth are unambiguously identified for pMOSFETs, i.e., loop, loop-shift, and up-loop. The loop dominates ΔVth at a relatively short time (< 1 s). After stressing for a longer time, the whole loop is shifted in the negative direction. Unlike the loop, the up-loop cannot readily be recharged after recovery. In addition to the generated interface states, three different types of positive charges are formed in the Hf-based stacks, i.e., cyclic positive charges (CPC), antineutralization positive charges (ANPC), and as-grown hole trapping (AHT). Each type of defect has its unique signatures and properties. CPC can repeatedly be charged and discharged by alternating the gate bias polarity. ANPC is more difficult to neutralize, whereas AHT is harder to charge. Both the generated interface states and the AHT saturate at longer stress time, but ANPC does not. ANPC reduces at higher measurement temperature, but CPC is insensitive to temperature. The relation between each type of defect and each component of ΔVth is clarified. [ABSTRACT FROM AUTHOR]

p-MOSFET negative bias temperature instability (NBTI) has become the most critical reliability issue for state-of-the-art CMOS technology. This paper investigates the effects of interface states (Nit) and oxide positive charges (PCs) on NBTI. Evidence shows how the importance of and PC is affected by stress temperature. PC has a dominative contribution to the NBTI at lower temperatures (< 373 K), whereas increases obviously above 373 K. Two kinds of PC are distinguished by the generation and recovery dynamics. One is the trapped holes (THs) which is the main part of PC at lower temperatures. The other is the generated PC of which generation is accelerated by temperature. NBTI recovery mainly results from TH detrapping. To find out the hole's influence on NBTI, the hole-injection and hole-energy effects on and PC formation are studied. It will be shown that the case is different to and PC. In addition, on-the-fly technique is used to eliminate the recovery during measurements. Analysis shows that is unimportant and that PC dominates the NBTI when measured by the nonrecovery technique. Moreover, the behaviors of TH, such as saturation and temperature independent, are also explained in this paper. [ABSTRACT FROM PUBLISHER]

Abstract: This work investigates the anneal-induced positive charge in Hf-based dielectrics. It is found that anneal in forming gas produces substantially more positive charge than that in N2 at 500 °C, indicating that hydrogen is a reactant for the positive charging. Positive charging is thermally accelerated and can occur in both HfO2 and Hf-silicates. Nitridation of either interfacial layer or whole dielectric stack enhances the positive charging significantly. These positive charges have a large sample-to-sample variation and are stable. For the first time, both mobile and fixed charges are simultaneously observed for Hf-stacks. [Copyright &y& Elsevier]

Abstract: The occurrence of sprite halos has been found almost solely in association with cloud-to-ground lightning flashes due to the release of positive charges (Miyasato et al., Geophysical Research Letters 29(21), 2033). Here, a numerical simulation method is used to study the positive charges producing sprite halos. A particle model, combined with the quasi-electrostatic (QE) model, is used to take account of the positive charges centered at two altitudes of 5 and 10km. The altitude of 10km is a typical position of positive charge in thunderstorm convective regions. The choice of an altitude of 5km is based on observations for the positive sprite-producing charges, which are located at the altitude range of 4–7km. Results show that sprite halos can be produced by positive charges at both altitudes. The region where sprite halos occur is determined mostly by the values of the released positive charges, which is in good agreement with the previous observations. The variation of the region of positive charges is approximately equivalent to the variation of the value of positive charge. The time when positive charge is released determines the intensity of optical emission from a sprite halo. Typically, the positive charge of 100 or 200C released at an altitude of 10 or 5km, respectively, within a time of 0.6ms will produce a sprite halo with a maximum optical intensity of ∼1×107 R. The estimated threshold of positive charges at which sprite halos are produced is consistent with the value estimated from the observed sprite halos. [Copyright &y& Elsevier]

The high hole mobility of Ge makes it a strong candidate for end of roadmap pMOSFETs and low interface states have been achieved for the Al2O3/GeO2/Ge gate-stack. This structure, however, suffers from significant negative bias temperature instability (NBTI), dominated by positive charge (PC) in Al2O3GeO2. An in-depth understanding of the PCs will assist in the minimization of NBTI and the defect energy distribution will provide valuable information. The energy distribution also provides the effective charge density at a given surface potential, a key parameter required for simulating the impact of NBTI on device and circuit performance. For the first time, this letter reports the energy distribution of the PC in Al2O3GeO2 on Ge. It is found that the energy density of the PC has a clear peak near Ge Ec at the interface and a relatively low level between Ec and Ev. Below Ev at the interface, it increases rapidly and screens 20% of the Vg rise. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Hole trapping and NBTI is substantial and the threshold voltage shift can be close to 1V for Ge/GeO2/Al2O3. [•] A new energy switching model has been proposed for the charging and discharging of hole traps for Ge/GeO2/Al2O3. [•] Unlike Si sample, the energy level of hole traps rises after charging and lowers after neutralization for Ge sample. [Copyright &y& Elsevier]

• Positive charges from H 2 O molecule induced the parasitic current path, resulting in anomalous hump in subthreshold region at elevated temperature, which disappeared after N 2 annealing. • Hump still existed under PBS, while weakened hump were observed under NBS due to positive charges trapping. In this work, we investigated an anomalous hump in the bottom-gate amorphous-InGaZnO thin-film transistors. The hump in the subthreshold region appeared at elevated temperature and disappeared after N 2 atmosphere annealing. The anomalous hump phenomenon is attributed to the existence of both main current path composed by electron and parasitic current path induced by positive charges formed by adsorbed H 2 O molecules. With the increase of the testing temperature, the hump effect becomes significant since the formation of positive charges is strengthened by heat. This hump can be weakened by negative bias temperature instability stress at high temperature due to the charge-trapping mechanism. [ABSTRACT FROM AUTHOR]

The bacteria and fungi captured on heat insulating materials or air filter media in the ventilation system in civil flights may reentrant into the indoor air which poses a threat to passengers' health. The E. coli and B. subtilis bacteria survival rates on the heat insulating blankets typically used as padding materials inside the aircraft walls under the mimicked environmental condition were studied. Then the antibacterial performance of positively charged electret and chitosan modified filter media which can be used in the ventilation systems against E. coli bacteria was investigated. Our results showed that the E. coli survival rate deceased to less than 0.2% and that of the B. subtilis decreased to less than 2.1% of the control samples on the hydrophilic and hydrophobic blankets under the mimic conditions after one flight cycle. The survival rate of E. coli on the positively charged electret filter media decreased to less than 30% compared to the uncharged filter media after six hours due to the disruption of their metabolic balance by the positive charges on the fibers surface. Moreover, the E. coli survival rate on the pure nylon, nylon/chitosan and chitosan dipped nylon-6 nanofibrous filter media decreased to 8.4%, 7.1% and 2.8% after 120 min, respectively. This study sheds light on fabrication of the eco-friendly antibacterial filter materials for the ventilation systems. Image 1 • Survival rates of typical bacteria were measured under mimicked civil flight conditions. • PTFE membrane composite air filter media were positively charged by corona discharge. • Chitosan was used to modified nylon-6 composite materials by electrospinning method. • Both positive charges and chitosan on filter showed effective antibacterial capacity. • Important parameters were provided to study the antimicrobial properties of air filter media. [ABSTRACT FROM AUTHOR]

A variety of triphenylamine (TPA) are shown to undergo C–C bond formation using quinone-based chloranil/H+ reagent as the metal free oxidative system to afford triphenylamine dimers very conveniently. Then, TPA dimers have been further converted to the emission color tunable compounds via simple chemical transformations. Importantly, we established the primary relationship between chemical structures with the optical behaviors from the aspect of emission (λ em) wavelength, fluorescence life time (τ) and aggregation-induced-emission (AIE) property in this work. The further application of these compounds to cell imaging was fully demonstrated. Image 1 [ABSTRACT FROM AUTHOR]

In this letter, we demonstrate that negative bias temperature instability of high-k (HfO2 /SiO2) gate dielectric stacks can be greatly improved by incorporating fluorine and engineering its concentration depth profile with respect to HfO2/SiO2 interface. It was found that fluorine is easily incorporated in HfO2/SiO2 at low temperatures (≤ 400 °C) by F2 anneal in the presence of UV radiation. Fluorine tends to segregate at the HfO2/SiO2 interface and, to a lesser extent, diffuses into the underlying SiO2/Si interface. The HfO2/SiO2 stacks with F addition show significantly reduced (<50%) positive charge trapping and interface states generation compared to control samples without F. [ABSTRACT FROM AUTHOR]

Bacterial resistance induced by the use of antibiotics has provided a chance for the development of antimicrobial peptides (AMPs), and modification of AMPs to enhance the antibacterial activity or stability has become a research focus. PMAP‐37 is an AMP isolated from porcine myeloid marrow, and studies on its modification have not yet been reported. In this study, three PMAP‐37 analogs named PMAP‐37(F9‐R), PMAP‐37(F34‐R), and PMAP‐37(F9/34‐R) were designed by residue substitution to enhance the positive charge. The antimicrobial activity of PMAP‐37 and its analogs in vitro and in vivo were detected. The results showed that compared with PMAP‐37, PMAP‐37(F9‐R) and PMAP‐37(F9/34‐R) exhibited antibacterial activity against S. flexneri CICC21534. Although PMAP‐37(F34‐R) had no antibacterial activity against S. flexneri CICC21534, its minimal inhibitory concentrations (MICs) were significantly lower than those of PMAP‐37 against most bacterial strains. Besides, all PMAP‐37 analogs were pH stable, retaining stable antibacterial activity after treatment with solution from pH 2 to pH 8/9. In addition, the PMAP‐37 analogs displayed increased thermal stability, and PMAP‐37(F34‐R) retained >60% antibacterial activity after boiling for 2 hours. Furthermore, the PMAP‐37 analogs exhibited impressive therapeutic efficacy in bacterial infections by reducing bacterial burden and inflammatory damage in the lung and liver, resulting in a reduction in mortality. Notably, the therapeutic effect of PMAP‐37(F34‐R) was comparable to that of ceftiofur sodium, and even superior to antibiotics in L. monocytogenes CICC21533 infection model. In conclusion, the PMAP‐37(F34‐R) may be a candidate for the treatment of bacterial infections in the clinic. [ABSTRACT FROM AUTHOR]