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In this work, a highly stretchable and sensitive strain sensor using silver nanowires (Ag NWs)/multi-walled carbon nanotubes (MWCNTs) on hair band is proposed. The fabrication process of such sensors enabled scalable and facile production with low cost by dipping hair band into Ag NWs/MWCNTs composites suspension. The sensing performance of the sensors was optimized by tuning the Ag NWs/MWCNTs mass ratio. The hair band based strain sensor with Ag NWs/MWCNTs mass ratio of 30 exhibited the best performance with high sensitivity of 416.0 and good stretchability up to 70%. Moreover, great repeatability and long-term stability could be achieved over 7500 cycles of stretch-release. This Ag NWs/MWCNTs-hair band sensor can be used for monitoring human motions and swallowing action.

HfOx-based resistive random-access memory devices have shown great potential in next-generation non-volatile memory devices, but they are not optimized as synaptic devices for neuromorphic systems. In this paper, the fabrication and biological synaptic behavior of HfO2/HfOx bilayered ultrathin memory devices is studied. 4 nm non-stoichiometric HfOx films were prepared on the TiN-coated Si substrate by plasma-enhanced atomic layer deposition (PEALD) using Hf[N(C2H5)CH3]4 (TEMAH) and hydrogen plasma. 2 nm stoichiometric HfO2 films were then deposited by thermal atomic layer deposition (TALD) using TEMAH and H2O precursors. X-ray photoelectron spectroscopy and electron energy loss spectroscopy were used to analyze the oxygen vacancy concentrations in HfO2/HfOx bilayer films. The effect of oxygen vacancy concentration in non-stoichiometric HfOx layers on resistive switching characteristics of Pt/HfO2/HfOx/TiN bilayered memristive devices has been explored. The memristor with 12.1% oxygen vacancy content in the HfOx layer shows better comprehensive properties with the optimal pulse energy consumption, reset switching speed and DC endurance and retention properties. Each operation is evaluated in a range of approximately ten-picojoules. Some important biological synaptic functions such as nonlinear transmission characteristics, short-term and long-term plasticity, paired-pulse facilitation, spike-timing-dependent plasticity and conditioned reflex have also been demonstrated in optimized memristive devices. This HfO2/HfOx ultrathin memristor is used for an attractive large-scale hardware implementation of neuromorphic simulations.

In this letter, biologic synaptic functions of organic-inorganic hybrid memristors using novel Ti-based maleic acid (Ti-MA)/TiO2 ultrathin films have been demonstrated. The memristive functional layer consists of 4-nm Ti-MA and 4-nm TiO2, which was fabricated at 160° C by molecular layer deposition (MLD)/atomic layer deposition (ALD), respectively. A typical bipolar resistive switching characteristic has been confirmed in the TaN/Ti-MA/TiO2/Pt bilayer memristors with the space charge limited current model. Using different electrical pulse modules, several important biologic synaptic functions such as nonlinear transmission characteristics, short-/long-term plasticity, paired-pulse facilitation, and spike-timing-dependent plasticity have been achieved. The organic-inorganic hybrid memristors of ultrathin bilayer Ti-MA/TiO2 derived by low temperature MLD/ALD are attractive for neuromorphic simulation and flexible neuroscience applications.

Combining wide-bandgap and narrow-bandgap perovskites to construct monolithic all-perovskite tandem solar cells offers avenues for continued increases in photovoltaic (PV) power conversion efficiencies (PCEs). However, actual efficiencies today are diminished by the subpar performance of narrow-bandgap subcells. Here we report a strategy to reduce Sn vacancies in mixed Pb–Sn narrow-bandgap perovskites that use metallic tin to reduce the Sn4+ (an oxidation product of Sn2+) to Sn2+ via a comproportionation reaction. We increase, thereby, the charge-carrier diffusion length in narrow-bandgap perovskites to 3 μm for the best materials. We obtain a PCE of 21.1% for 1.22-eV narrow-bandgap solar cells. We fabricate monolithic all-perovskite tandem cells with certified PCEs of 24.8% for small-area devices (0.049 cm2) and of 22.1% for large-area devices (1.05 cm2). The tandem cells retain 90% of their performance following 463 h of operation at the maximum power point under full 1-sun illumination. Improvements in the efficiency and stability of low-bandgap perovskite solar cells are key to enabling all-perovskite solar cells. Here, Lin et al. use metallic tin to prevent oxidation in such low-gap perovskite and demonstrate 24.8%-efficient tandems that are stable for over 400 h under operating conditions.

Metal–insulator–metal (MIM) capacitors fabricated with Zr-Sn-Ti-O dielectrics by the plasma-enhanced atomic layer deposition (PEALD) were first demonstrated. By changing the pulse cycle ratio and cycle number of PEALD, the comprehensive electrical properties of the Zr-Sn-Ti-O MIM capacitors were optimized to meet the requirements of system-level chips for the high-density MIM capacitors. When the cycle ratio of ZrO2:SnO2:TiO2 is 2:10:2, the sample of Zr0.45Sn0.06Ti0.48O2 shows the best electrical properties: a capacitance density of 10.8 fF/ $\mu \text{m}^{{2}}$ , a quadratic voltage linearity of −83 ppm/V2, a leakage current density of $5\times 10^{{-7}}$ A/cm2 at 3 V, a breakdown voltage of 6.8 V, and a temperature linearity coefficient of 95.1 ppm/°C. These results indicate that PEALD Zr-Sn-Ti-O dielectrics are promising candidates for future high-density MIM capacitor applications in radio frequency and analog-/mixed-signal integrated circuits.

A charge trapping memory device using Ta2O5/Al2O3/TiO2/Al2O3/Ta2O5 (TATiAT) nanocomposite high-k dielectrics as charge trapping layer (CTL) and amorphous Al2O3 as the tunneling and blocking layers has been investigated, in which all the high-k dielectric films were fabricated by atomic layer deposition (ALD) technique. A large memory window of 10.0 V with higher charge trap density of 1.10 × 1013 cm−2 at gate voltage of ±10 V has been achieved. The better storage characteristic is attributed to the inter-diffusion between nanocomposite high-k oxides and the formation of more oxygen vacancies in CTL. The device shows the fast P/E speed and excellent endurance characteristics. A 70% initial memory window can be maintained after 10 years of retention by using the extrapolation method. The large conduction band offsets of 1.02 eV between TATiAT and Al2O3 is beneficial to retention characteristic due to the deep trap level.

In the semiconductors and related industries, the fabrication of nanostructures and nanopatterns has become progressive demand for achieving near-atomic accuracy and selectivity in etching different materials, particularly in ultra-thin gate dielectrics and ultra-thin channels used in field-effect transistors and other nanodevices below 10 nm scale. Atomic layer etching (ALE) is a novel technique for removing thin layers of material using sequential and self-limiting reactions. Different from most ALE processes using plasma-enhanced or other energetic particles-enhanced surface reactions, thermal ALE realizes isotropic atomic-level etch control based on sequential thermal-drive reaction steps that are self-terminating and self-saturating. Thermal ALE can be viewed as the reverse of atomic layer deposition (ALD), both of which define the atomic layer removal and growth steps required for advanced semiconductor fabrication. In this review, we focus on the concept and basic characteristics of the thermal ALE in comparison with ALD. Several typical thermal ALE mechanisms including fluorination and ligand-exchange, conversion-etch, oxidation and fluorination reactions are intensively introduced. The pros and cons of thermal ALE, plasma ALE, and traditional plasma etching are compared. Some representative materials and their typical thermal ALE processes are summarized. Finally, the outlook and challenges of thermal ALE are addressed. Keywords: Thermal atomic layer etching, Atomic layer deposition, Self-limiting, Reaction mechanism, Atomic-scale precision

When calculating RCS using the Graphical Electromagnetic Algorithm (GRECO), Firstly we must obtain the coordinate values and normal vectors of each point on the target illumination surface, which is limited to the computer hardware conditions. So when we calculating RCS at high frequencies often accompanied by insufficient pixel accuracy, therefore it can affect the calculation accuracy. The method of turning straight into a curve adopts a curved surface as close as possible to the real situation instead of the facet information represented by pixels, thereby improving the calculation accuracy of the model at high frequency.

The introduction of metal nanocrystals (NCs) has been confirmed to improve electrical uniformity of oxide-based resistive random access memory (RRAM) devices significantly; however, the current reports do not systematically elucidate the relationship between the size/distribution of NCs and the electrical uniformity of RRAM devices. In this paper, we focused on the impact of metal NCs size and areal density on the resistive switching (RS) performances of oxide RRAM by atomic layer deposition (ALD) based on the experimental results and theoretical calculation. The dependence of ALD cycles of 50–130 during Pt or CoPt x NCs growth on the RS parameters of Al2O3 or HfO2 memory units has been evaluated systematically. The RRAM embedded Pt or CoPt x NCs shows the trends: with increasing ALD cycles, the forming voltage, set/reset voltage, the resistance in off and on state, and ${R}_{ \mathrm{\scriptscriptstyle OFF}}/{R}_{ \mathrm{\scriptscriptstyle ON}}$ ratio entirely first decrease, then flatten, and increase later with a minimum value at about 100 cycles. Although all metal NCs with various sizes enhance the electric field strength compared to at the planar region, only metal NCs with proper NCs size and areal density (9 nm/6– $10\times 10^{\textsf {11}}$ /cm2 in this paper) can effectively produce stronger localized electric field at the tip of metal NCs, leading to optimal RS behavior.

We pioneered to employ room temperature atomic layer deposition (RTALD) to fabricate flexible Al-Ti-O based metal-insulator-metal (MIM) capacitors on three polymer substrates of polyethylene terephthalate (PET), polyimide (PI) and epoxy resin (epoxy) without any post-processing. Zn was introduced to Al-Ti-O dielectrics to tune its electrical properties through varying ALD cycle ratio and cycle number. Under the optimal processing, the flexible MIM capacitors of Al1.56Ti0.47Zn0.06O3 exhibits comprehensively better performance such as higher capacitance density of 7.4 fF/μm2, smaller leakage current density of 2 × 10−8 A/cm2 at 3 V, and reasonable quadratic voltage linearity of 422 ppm/V2. X-ray photoelectron spectroscopy analyses reveal that the incorporation of a slight amount of Zn into Al-Ti-O dielectrics significantly decreases the oxygen vacancy concentration from 6.7% to 0.8%, beneficial for the improvement of electrical performance. Furthermore, our 2 × 2 cm2 flexible MIM capacitors could bear 4000 bending cycles at bending radius of 8.2 mm, showing better electrical stability. These results indicate that RTALD-derived Al-Ti-Zn-O dielectrics are competitive MIM capacitor candidates for flexible electronics and wearable devices. RTALD technology exhibits exciting potentials in flexible electronic device fabrication.

Introduction The aim of this study is to investigate the feasibility of the application of the laparoscopic technique in perihilar cholangiocarcinoma. Methods A total of nine cases of patients who received laparoscopic perihilar cholangiocarcinoma surgery from January 2007 to May 2014 were retrospectively analyzed. The Bismuth subtypes consisted of one case of type I, three cases of type II, two cases of type IIIb, and three cases type IV. Results Radical resection was conducted in six cases: two cases (type II) with the caudate lobe resection, and two cases (type IIIb) with the left hepatectomy and caudate lobe resection. The mean operation time was 7.3 h (5.5–8.5 h), the mean blood loss was 503 ml (150–850 ml). The pathological tests showed two cases of poorly differentiated adenocarcinoma, three cases of moderately differentiated adenocarcinoma, and four cases of highly differentiated adenocarcinoma. Conclusion Laparoscopic technology in the surgical treatment of perihilar cholangiocarcinoma is an option for the resection approach.

The HfO2/TiO2/HfO2 trilayer-structure resistive random access memory (RRAM) devices have been fabricated on Pt- and TiN-coated Si substrates with Pt top electrodes by atomic layer deposition (ALD). The effect of the bottom electrodes of Pt and TiN on the resistive switching properties of trilayer-structure units has been investigated. Both Pt/HfO2/TiO2/HfO2/Pt and Pt/HfO2/TiO2/HfO2/TiN exhibit typical bipolar resistive switching behavior. The dominant conduction mechanisms in low and high resistance states (LRS and HRS) of both memory cells are Ohmic behavior and space-charge-limited current, respectively. It is found that the bottom electrodes of Pt and TiN have great influence on the electroforming polarity preference, ratio of high and low resistance, and dispersion of the operating voltages of trilayer-structure memory cells. Compared to using symmetric Pt top/bottom electrodes, the RRAM cells using asymmetric Pt top/TiN bottom electrodes show smaller negative forming voltage of −3.7 V, relatively narrow distribution of the set/reset voltages and lower ratio of high and low resistances of 102. The electrode-dependent electroforming polarity can be interpreted by considering electrodes’ chemical activity with oxygen, the related reactions at anode, and the nonuniform distribution of oxygen vacancy concentration in trilayer-structure of HfO2/TiO2/HfO2 on Pt- and TiN-coated Si. Moreover, for Pt/HfO2/TiO2/HfO2/TiN devices, the TiN electrode as oxygen reservoir plays an important role in reducing forming voltage and improving uniformity of resistive switching parameters.

In situ-formed SiO2 was introduced into HfO2 gate dielectrics on Ge substrate as interlayer by plasma-enhanced atomic layer deposition (PEALD). The interfacial, electrical, and band alignment characteristics of the HfO2/SiO2 high-k gate dielectric stacks on Ge have been well investigated. It has been demonstrated that Si-O-Ge interlayer is formed on Ge surface during the in situ PEALD SiO2 deposition process. This interlayer shows fantastic thermal stability during annealing without obvious Hf-silicates formation. In addition, it can also suppress the GeO2 degradation. The electrical measurements show that capacitance equivalent thickness of 1.53 nm and a leakage current density of 2.1 × 10−3 A/cm2 at gate bias of Vfb + 1 V was obtained for the annealed sample. The conduction (valence) band offsets at the HfO2/SiO2/Ge interface with and without PDA are found to be 2.24 (2.69) and 2.48 (2.45) eV, respectively. These results indicate that in situ PEALD SiO2 may be a promising interfacial control layer for the realization of high-quality Ge-based transistor devices. Moreover, it can be demonstrated that PEALD is a much more powerful technology for ultrathin interfacial control layer deposition than MOCVD.

Al2O3- or HfO2-based nanocomposite structures with embedded CoPtx nanocrystals (NCs) on TiN-coated Si substrates have been prepared by combination of thermal atomic layer deposition (ALD) and plasma-enhanced ALD for resistive random access memory (RRAM) applications. The impact of CoPtx NCs and their average size/density on the resistive switching properties has been explored. Compared to the control sample without CoPtx NCs, ALD-derived Pt/oxide/100 cycle-CoPtx NCs/TiN/SiO2/Si exhibits a typical bipolar, reliable, and reproducible resistive switching behavior, such as sharp distribution of RRAM parameters, smaller set/reset voltages, stable resistance ratio (≥102) of OFF/ON states, better switching endurance up to 104 cycles, and longer data retention over 105 s. The possible resistive switching mechanism based on nanocomposite structures of oxide/CoPtx NCs has been proposed. The dominant conduction mechanisms in low- and high-resistance states of oxide-based device units with embedded CoPtx NCs are Ohmi...

Atomic layer deposition (ALD) is a powerful nanofabrication technique for the preparation of uniform, conformal, and ultrathin films and allows accurate control of the composition and thickness of thin films at the atomic level. To date, ALD has been used for the growth of various materials, including oxides, nitrides, sulfides, metals, elements, compound semiconductors, and organic and organic–inorganic hybrid materials. As one of the most important inorganic materials, silicon dioxide (SiO2) has been used in the fields of microelectronics, catalysis, and energy storage and conversion. Various SiO2 ALD methods have been developed, which have expanded the research and applications of ALD chemistry and technology. Recent advances concerning the reaction mechanisms of SiO2 ALD have further deepened our understanding of the surface chemistry and related catalysis in the ALD of SiO2 and other oxides. Thin films of SiO2 can be obtained by means of thermal ALD and energy-enhanced ALD. Thermal ALD of SiO2 includ...

Graphical abstractDisplay Omitted Charge trapping memory devices based on HfAlO thin film were deposited.The memory devices based on HfAlO thin film had good charge trapping capability.Intensive mixing of two high-k materials can improve the charge trapping capability.The RTA-treated sample exhibited good program/erase and endurance performances.About 21% of the trapped charges were remained after 10-years retention time. HfAlO composite oxide was prepared as the charge trapping layer to improve the performance of our memory devices. The results showed that the device with HfAlO charge trapping layer had excellent charge trapping capability. The RTA treatment can make HfO2 and Al2O3 mixing more uniformly, and enlarge the inter-diffusion of the two materials, leading to the enhancement of the charge trapping capability. Meanwhile, the sample with RTA treatment exhibited fast program/erase speed, good retention and endurance performance, indicating that the memory device with high-k composite oxide charge trapping layer could be a promising candidate for future memory applications.

A simple high-throughput approach is presented in this work to fabricate the Au nanoparticles (NPs)/nanogap/Au NPs structure for surface enhanced Raman scattering (SERS). This plasmonic nanostructure can be prepared feasibly by the combination of rapid thermal annealing (RTA), atomic layer deposition (ALD) and chemical etching process. The nanogap size between Au NPs can be easily and precisely tuned to nanometer scale by adjusting the thickness of sacrificial ALD Al2O3 layer. Finite-difference time-domain (FDTD) simulation data indicate that most of enhanced field locates at Au NPs nanogap area. Moreover, Au NPs/nanogap/Au NPs structure with smaller gap exhibits the larger electromagnetic field. Experimental results agree well with FDTD simulation data, the plasmonic structure with smaller nanogap size has a stronger Raman intensity. There is highly strong plasmonic coupling in the Au nanogap, so that a great SERS effect is obtained when detecting methylene blue (MB) molecules with an enhancement factor (EF) over 107. Furthermore, this plasmonic nanostructure can be designed on large area with high density and high intensity hot spots. This strategy of producing nanoscale metal gap on large area has significant implications for ultrasensitive Raman detection and practical SERS application.

Recently, ferroelectric tunnel junctions have attracted much attention due to their potential applications in non-destructive readout non-volatile memories. Using a semiconductor electrode has been proven effective to enhance the tunnelling electroresistance in ferroelectric tunnel junctions. Here we report a systematic investigation on electroresistance of Pt/BaTiO3/Nb:SrTiO3 metal/ferroelectric/semiconductor tunnel junctions by engineering the Schottky barrier on Nb:SrTiO3 surface via varying BaTiO3 thickness and Nb doping concentration. The optimum ON/OFF ratio as great as 6.0 × 106, comparable to that of commercial Flash memories, is achieved in a device with 0.1 wt% Nb concentration and a 4-unit-cell-thick BaTiO3 barrier. With this thinnest BaTiO3 barrier, which shows a negligible resistance to the tunnelling current but is still ferroelectric, the device is reduced to a polarization-modulated metal/semiconductor Schottky junction that exhibits a more efficient control on the tunnelling resistance to produce the giant electroresistance observed. These results may facilitate the design of high performance non-volatile resistive memories., Alternative non-volatile memory designs are needed as the scaling of flash-based memories reaches its physical limits. By careful engineering, Xi et al. achieve ON/OFF ratios as great as 6.0 × 106 in ferroelectric tunnel junction devices making them comparable to commercial flash memories.

Charge trapping memory cells using Ti–Al–O (TAO) film as charge trapping layer and amorphous Al 2 O 3 as the tunneling and blocking layers were fabricated on Si substrates by atomic layer deposition method. As-deposited TAO films were annealed at 700 °C, 800 °C and 900 °C for 3 min in N 2 with a rapid thermal annealing process to form nanocrystals. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the microstructure and band diagram of the heterostructures. The electrical characteristics and charge storage properties of the Al 2 O 3 /TAO/Al 2 O 3 /Si stack structures were also evaluated. Compared to 700 °C and 900 °C samples, the memory cells annealed at 800 °C exhibit better memory performance with larger memory window of 4.8 V at ± 6 V sweeping, higher program/erase speed and excellent endurance.

The growth of Pt nanocrystals (NCs) on Al2O3 surface via atomic layer deposition (ALD) was investigated deeply. A charge trapping memory using Pt NC as charge trapping layer and amorphous ALD Al2O3/HfO2 as the tunneling/blocking layers was fabricated. Pure metallic Pt NC can be formed at the initial growth stage, following the nucleation incubation model. Electrical measurements of p-Si\Al2O3\Pt NCs\HfO2 show a larger memory window of 6.6 V at the sweeping gate voltage of ±12 V and ∼73% retention property after 105 s. Fowler–Nordheim tunneling serves as the dominant tunneling mechanism at the applied gate voltage of 10 V. Compared to that of 4.0 V with HfO2 blocking layer, control sample with Al2O3 blocking layer shows negligible memory window of 0.3 V at ±10 V, which is attributed to the smaller electric field intensity in the Al2O3 tunneling layer of stacking structures of p-Si\Al2O3\Pt NCs\Al2O3. ALD Pt NCs with a high density of 1.0 × 1012/cm2 provides a potential approach to fabricate large area nanocrystals for future ultrahigh density nonvolatile memory applications.

A nonvolatile memory structure with a high-k composite of ZnO-TiO2 as a charge-trapping dielectric was fabricated by using rf-sputtering and atomic layer deposition techniques, in which the potential of the conduction-band minimum of the composite was designed to be lower than that of Si by the use of the special energy-band offsets among Si, ZnO, and TiO2. Compared to the conduction-band minimum of Si, a relatively negative potential of the high-k composite leads to a continuous rise in the shift of the flat-band potential of the memory device except a drop at the beginning part of the time-dependent retention curve after a programming operation. The drop was attributed to the escape of trapped charges at the Si/Al2O3 interface. After extracting the contribution to the deterioration of the retention curve from the traps at the Si/Al2O3 interface, it was identified that the band alignment in a charge-trapping memory device dominated its retention behaviors.

Objective To investigate the patient satisfaction with medications commonly used for migraine therapy in patients seen in headache clinic in China with emphasis on the evaluation of Chinese patent medicine (CPM) in relieving acute migraine attack. Methods Patients admitted at headache clinics in the neurological departments of four hospitals during April to October 2011 were enrolled in the investigation. The questionnaire was designed based on the validation of a diagnostic questionnaire for a population-based survey in China in 2009. Results Among 219 eligible patients, 58% had used CPM at the acute attack of migraine while the guideline-recommended treatments were seldom used. However, patients using CPMs were less satisfied than those using Western Medicines (WMs) in either single medication groups or mixed medication groups ( P < 0.05). Conclusion Fifty-eight percent of the eligible respondents in Guangdong and Guangxi Province had used CPM at the acute attack of migraine, but based on our data, the effect of CPM on treating migraine attack was poor with low satisfaction compared with WMs. However, many factors may bias or explain our findings. This suggests the need for accelerated research in understanding patient choice, treatment availability, and use of medications.

In 2010, the first offshore wind turbine with integrated installation was established in Qidong sea area of Jiangsu Province, China, which led to the implementation phase of one-step-installation technique based on the design and construction of large-scale bucket-top-bearing (LSBTB) bucket foundation. The critical technique of LSBTB bucket foundation included self-floating towing, penetration with adjustment of horizontal levelness, removability and one-step-installation. The process of one-step-installation included the prefabrication of LSBTB bucket foundation in onshore construction base, installation and debugging of wind power, overall water transportation of foundation and wind power system, and installation of foundation and offshore wind turbine on the appointed sea area. The cost of one-step-installation technique was about 5 000 Yuan/kW, which was 30%-50% lower than that of the existing technique. The prefabrication of LSBTB bucket foundation took about two months. During the one-step-installation process, the installation and debugging of wind power and overall water transportation need about one to two days in sea area within 35 m depth. After the proposed technique is industrialized, the cost will be further reduced, and the installation capacity is expected to be up to 500 wind turbines per year.

We report the characteristics of HfO2 films deposited on Ge substrates with and without La2O3 passivation at 250 °C by atomic layer deposition (ALD) using La[N(SiMe3)2]3 and Hf[N(CH3)(C2H5)]4 as the precursors. The HfO2 is observed to form defective HfGeOx at its interface during 500 °C postdeposition annealing. The insertion of an ultrathin La2O3 interfacial passivation layer effectively prevents the Ge outdiffusion and improves interfacial and electrical properties. Capacitance equivalent thickness (CET) of 1.35 nm with leakage current density JA of 8.3 × 10−4 A/cm2 at Vg = 1 V is achieved for the HfO2/La2O3 gate stacks on Ge substrates.

Atomic layer deposition (ALD) is a powerful nanofabrication technique for the preparation of uniform, conformal, and ultrathin films and allows accurate control of the composition and thickness of thin films at the atomic level. To date, ALD has been used for the growth of various materials, including oxides, nitrides, sulfides, metals, elements, compound semiconductors, and organic and organic–inorganic hybrid materials. As one of the most important inorganic materials, silicon dioxide (SiO2) has been used in the fields of microelectronics, catalysis, and energy storage and conversion. Various SiO2 ALD methods have been developed, which have expanded the research and applications of ALD chemistry and technology. Recent advances concerning the reaction mechanisms of SiO2 ALD have further deepened our understanding of the surface chemistry and related catalysis in the ALD of SiO2 and other oxides. Thin films of SiO2 can be obtained by means of thermal ALD and energy-enhanced ALD. Thermal ALD of SiO2 includ...

ZrO2 nanocrystallites based charge trap memory cells by incorporating a (ZrO2)0.6(SiO2)0.4 film as a charge trapping layer and amorphous Al2O3 as tunneling and blocking layer were prepared and investigated. The precipitation reaction in charge trapping layer forming ZrO2 nanocrystallites during rapid thermal annealing was investigated by transmission electron microscopy. The density and size of ZrO2 nanocrystallites are the critical factors for controlling the charge storage characteristics. The ZrO2 nanocrystallites based memory cells after postannealing at 800 ∘C for 60 s exhibit the best electrical characteristics and a low charge loss ∼5 % after 105 write/erase cycles operation.

LiTaO3 (LTO) ferroelectric nanocrystals and transparent polycarbonate (PC) composite thin films were prepared by a spin-coating technique. LTO (∼100 nm) nanocrystals with pure hexagonal phase were synthesized by a polymerizable complex route. The structure and morphology of LTO nanocrystals and LTO/PC composite films were studied by means of x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The transmittance and dielectric properties of LTO/PC composite films were also evaluated. The LTO/PC composite films show better transparency (90%) in visible light range with a band gap of 4.63 eV. The dielectric constant and loss of LTO/PC films is 4.0 and 0.05 at 10 kHz, respectively.

Charge trapping memory capacitors using (ZrO"2)"0"."8(SiO"2)"0"."2 film as charge trapping layer and amorphous Al"2O"3 as the tunneling layer and blocking layer were fabricated for nonvolatile semiconductor memory application. The ZrO"2 nanocrystallites with a size of 3-5nm precipitated from amorphous (ZrO"2)"0"."8(SiO"2)"0"."2 during rapid thermal annealing at 800^oC can serve as the storage nodes, with which a large hysteresis memory window of 7.5V at a sweeping gate voltage of 8V has been achieved. At 150^oC bake temperature, the memory capacitor exhibited an excellent endurance up to 10^5 write/erase cycles, after which a small charge loss of about 12% was achieved.

The GaAs surfaces were passivated by two kinds of chemical pretreatments (using NH4OH and (NH4)2S as passivation agents) for atomic layer deposited (ALD) Al2O3 dielectric film growth. The chemical information at Al2O3/GaAs interfaces was carefully characterized. The impact of surface treatments on the band alignments of ALD Al2O3 films on nGaAs (100) substrates was also investigated. After postdeposition annealing, the NH4OH passivated samples not only have a slight increase of the AsAs peaks with an appearance of As suboxide (AsOx) feature at Al2O3/GaAs interfaces but also exhibit a serious interfacial interdiffusion between Al2O3 and GaAs. However, the (NH4)2S passivated samples produce the GaS and AsS overlayers on GaAs, effectively preventing from the intermixed diffusion between Al2O3 films and GaAs substrates with a sharper interface. Both NH4OH and (NH4)2S passivated Al2O3 samples show the same band gap of 6.67 eV. The conduction band offset at Al2O3/GaAs interface for the (NH4)2S passivated samples have a slight enhancement of 0.14 eV in comparison to NH4OH passivated ones. Copyright © 2010 John Wiley & Sons, Ltd.

SrZrO 3 thin films are prepared on Pt/TiO 2 /SiO 2 /Si substrates by sol–gel process for resistive random access memory applications. The unipolar resistive switching characteristic is achieved in both stoichiometric and Zr-deficient SrZrO 3 thin films. Formation and rupture of filaments composed of oxygen vacancies are proposed to explain the observed resistive switching behaviors. By introducing oxygen vacancies into SrZrO 3 through making the film Zr-deficient, the conduction mechanism of the high resistance state changes from Ohmic to space charge limited behavior. This may be ascribed to more deep traps associated with oxygen vacancies due to Zr-deficiency. Switching endurance is enhanced significantly in Zr-deficient SrZrO 3 due to the reduced Joule heating.

Electroplating of copper is widely used for the fabrication of interconnections of printed circuit boards, in which via-holes are used to connect conductive layers. Self-annealing is an important feature of electroplated copper which significantly alters its microstructures. The degradation of texture and the enhancement of texture in electroplated copper during self-annealing process are observed by X-ray diffraction (XRD) and electron backscattering diffraction (EBSD). The mechanism of this transformation is discussed and illustrated.

In this work, we present light-controlled resistive switches with p-Si/HfO2/Pt structures, in which the resistance can be controlled by a combination of electrical pulses and light. The devices have a large switching ratio (over 104) and good uniformity. Connecting two devices with a conventional resistor enables one to implement light-controlled material implication (IMP). Based on the light-controlled IMP logic, light-controlled NAND and light-controlled OR logic operations were also executed in the same devices.

Pb0.56Sr0.44Zr0.52Ti0.48O3 (PSZT) inverse opal photonic crystals (PCs) have been synthesized by a process of self-assembly in combination with a sol–gel procedure. PSZT inverse opals show pure perovskite structure with good orders in three dimensions. The evident photonic band gaps have been observed in the transmittance spectra with a blue-shift phenomenon due to the decrease of opal template periods. PSZT inverse opals also exhibit the reflection peaks in basic agreement with the calculated results. This three-dimensional (3D) ordered PSZT inverse opals have shown interesting optical characteristics and potential applications in optoelectronic and photonic devices.

To determine whether pegylated liposomal doxorubicin (PLD) could control the metastasis beyond primary tumor, the efficacy of PLD was evaluated in terms of metastatic growth inhibition and increasing life span in a murine lung metastasis model. As early as 20 days after C57BL/6 mice were inoculated with 2 x 10(6) murine Lewis lung carcinoma cells into the right legs, metastases could be observed in the lungs. Comparing the metastatic status of the PLD treatment conducted one day with one week after the tumor implantation, pathological study of the metastasis in the lungs indicated that without the removal of primary tumor, PLD could prevent metastasis by suppressing the growth of primary tumor. To evaluate the direct antimetastasis ability of PLD with clinical relevance, a surgery was performed to resect the tumor-bearing limb. The treatment was started 3 days after the amputation with free doxorubicin or PLD. In this therapeutic model, PLD targeted directly to the metastasis in the lungs, which resulted in substantially longer survival time than free doxorubicin. Despite the superiority of PLD over free doxorubicin in treating pulmonary metastasis, our observation suggested that without the removal of primary tumor, the effect of PLD was only modest, and surgery plus multiple injections of PLD will be the best choice for patients with metastatic disease.

Semiconducting two-dimensional transition metal dichalcogenides are emerging as top candidates for post-silicon electronics. While most of them exhibit isotropic behaviour, lowering the lattice symmetry could induce anisotropic properties, which are both scientifically interesting and potentially useful. Here we present atomically thin rhenium disulfide (ReS2) flakes with unique distorted 1T structure, which exhibit in-plane anisotropic properties. We fabricated monolayer and few-layer ReS2 field-effect transistors, which exhibit competitive performance with large current on/off ratios (∼107) and low subthreshold swings (100 mV per decade). The observed anisotropic ratio along two principle axes reaches 3.1, which is the highest among all known two-dimensional semiconducting materials. Furthermore, we successfully demonstrated an integrated digital inverter with good performance by utilizing two ReS2 anisotropic field-effect transistors, suggesting the promising implementation of large-scale two-dimensional logic circuits. Our results underscore the unique properties of two-dimensional semiconducting materials with low crystal symmetry for future electronic applications., Many two-dimensional materials exhibit isotropic properties, but anisotropy can extend the functionality of future devices. Here, the authors fabricate field-effect transistors from single and few-layer rhenium disulfide and observe an anisotropic ratio of three to one along the two principle axes

Pb(Zr0.52Ti0.48)O3(PZT) ferroelectric thin films were deposited epitaxially, by pulsed laser deposition, on (001) SrTiO3substrates buffered with La0.7Sr0.3MnO3(LSMO) electrodes. AmorphousTiOxthin films were deposited on top of PZT at various temperatures and oxygen chamber pressures. Bipolar resistive switching characteristics of Pt/TiOx/PZT/LSMO heterostructures are found to vary withTiOxdeposition parameters, from an interface controlled ferroelectric diode behavior to a bulk-controlled conductive filament behavior. The observations are discussed in terms of the concentration and migration of oxygen vacancies in theTiOxlayer.

TiO2/LaAlO3(TiO2/LAO) heterostructures have been deposited on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition. Resistive switching characteristics of Pt/TiO2/LAO/Pt have been studied and discussed in comparison with those of Pt/TiO2/Pt. It is observed that the switching uniformity and the ON/OFF resistance ratio can be greatly improved by introducing the LAO layer. The observed resistive switching characteristics are discussed as a function of LAO thickness and explained by the preferential formation and rupture of conductive filaments, composed of oxygen vacancies, in the LAO layer.

Bi4Ti3O12 (BIT) films were prepared on Pt/TiO2/SiO2/Si substrates by the sol–gel method. A low electric field was in-situ applied to BIT films during rapid thermal annealing (RTA). It was first found that a bias electric field has great influence on the structure, orientation, and morphology of BIT films at proper temperatures. Under the electric field of very low V/cm, BIT films show highly c-axis-oriented growth with second phase of bismuth oxide at 600 and 650 °C. The possible origin is proposed. On one hand, the electrostatic energy provides an extra driving force and the co-interaction of the electrostatic energy and interface energy promotes the c-axis-oriented growth of the BIT grains. On the other hand, the second phase of bismuth oxide produced during RTA in an electric field also plays an important role in the control of film orientation.

Melon is one of the economically important and widely cultivated vegetable crops in the world. There is a wide genetic diversity in the cultivated and wild species of melon. Melon as one of the most consumed fruits, the development and ripening of fruit is known to be a complex developmental process that involves many biochemical and physiological changes including the breakdown of chlorophyll, degradation of the cell wall, increase in sugars content, alteration in pigment biosynthesis, and the accumulation of flavour and aromatic compounds. However, the information on genetic engineering and molecular biology of melon is very limited. With the development of genetics and molecular biology, a large number of quality/ripening-regulated genes involved in pigmentation, vitamin, soluble carbohydrate metabolism, cell wall metabolism and ethylene biosynthesis have been identified in melons. Some genetic manipulations of melons have been proved to be useful technology to improve quality, sensory attributes, shelf life and other agronomic traits of melon fruit. This paper reviewed some progresses in the trangenic approach to improve quality traits of melon fruit.

Plasma-enhanced atomic layer deposition (PE-ALD) has been applied to prepare high-quality ultrathin films for microelectronics, catalysis, and energy applications. The possible pathways for SiO2 PE-ALD using aminosilanes and O2 plasma have been investigated by density functional theory calculations. The silane half-reaction between SiH4 and surface -OH is very difficult and requires a high activation free energy of 57.8 kcal mol(-1). The introduction of an aminosilane, such as BDMAS, can reduce the activation free energy to 11.0 kcal mol(-1) and the aminosilane plays the role of a self-catalyst in Si-O formation through the relevant half-reaction. Among the various species generated in O2 plasma, (3)O2 is inactive towards surface silane groups, similar to ordinary oxygen gas. The other three species, (1)O2, (1)O, and (3)O, can strongly oxidize surface silane groups through one-step or stepwise pathways. In the (3)O pathway, the triplet must be converted into the singlet and follow the (1)O pathway. Meanwhile, both (1)O and (3)O can decay to (1)O2 and enter into the relevant oxidation pathway. The concept of self-catalysis of aminosilanes may be invoked to design and prepare more effective Si precursors for SiO2 ALD. At the same time, the mechanism of strong surface oxidation by O2 plasma may be exploited in the PE-ALD preparation of other oxides, such as Al2O3, HfO2, ZrO2, and TiO2.

Amorphous lanthanum aluminate (LAO) gate dielectric has been grown on silicon substrates by low-pressure metalorganic chemical vapor deposition. The structure, morphology, thermal stability, bandgap, and electrical properties have been characterized by various techniques. The LAO films exhibit excellent thermal stability and keep noncrystalline structure even after 900°C rapid thermal anneal. The smooth surface and larger bandgap are also confirmed. By optimizing the processing, the minimume value of equivalent oxide thickness around 0.9 nm of LAO/Si has been achieved.

Metal–ferroelectric–insulator–semiconductor structures using LaAlO3 (LAO) layers as an insulating barrier have been investigated. LAO films were deposited on n-Si substrates by low-pressure metalorganic chemical vapor deposition (MOCVD). SrBi2Ta2O9 (SBT) films were prepared as ferroelectric layers at a low processing temperature of 650 °C by a metalorganic decomposition method. The MOCVD-derived LAO buffer layer shows an amorphous structure, relatively high dielectric constant, and good electrical properties. Au/SBT/LAO/n-Si exhibits a larger counterclockwise C–V memory window of 3.7 V and a lower leakage-current density of 2.5×10-8 A/cm2 at an applied voltage of 10 V. It has been confirmed that the hysteresis loop is caused by ferroelectricity. The Auger electron spectrometry depth profile indicates that the introduction of the LAO buffer layer prevents the interfacial diffusion between SBT and the Si substrate effectively and improves the interface quality.

The surface sol-gel (SSG), a solution-based and stepwise film growth technique, was developed to produce ultrathin zirconium oxide (ZrO2) films for high-k gate dielectric application. X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) measurements confirm the successful deposition of ultrathin polycrystalline ZrO2 films on Si substrate by the SSG method. Electrical measurements show that a large effective oxide thickness (EOT) of 2.4 nm with high leakage current was obtained, and a hysteresis in C-V curves and large fix charge density in ZrO2 films was observed, which related to the formation of substoichiometric silicon oxide in the interface. Surface nitridation of Si substrate by NH3 plasma can effectively reduce the leakage current and fixed or trapping charge density, as well as improve the interface properties. EOT of 2.21 nm with JA = 30.4 mA/cm2 at Vg = +1 V was demonstrated in ZrO2 films with a Si nitride barrier layer.

Pb(Zr0.52Ti0.48)O3 (PZT) nanocrystals and transparent polycarbonate (PC) composite thin films with useful properties for ferroelectric, piezoelectric and electro-optic devices were prepared by a spin-coating technique. Ultra-fine PZT (∼40–50 nm) nanocrystals with pure perovskite tetragonal phase were synthesized by a hydrothermal method. The structure and morphology of the composite thin films were studied by means of X-ray diffraction and scanning electron microscopy. To obtain the optimum electro-optic properties of poled composite films, the poling condition under an external electric field was optimized through the dielectric properties of PZT and PC polymer and effective field intensity theory. The electro-optic coefficient of the poled PZT/PC composite film is estimated to be 30.5 pm/V. The transparency spectra were measured and the optical band gaps of the unpoled, poled at 145 °C and poled at 165 °C composite thin films are estimated to be 4.26 eV, 4.21 eV and 4.18 eV, respectively. The measured dielectric constants of PZT/PC are in good agreement with the calculated values for the composite with a very small PZT volume fraction, based on the Onsager effective-field theory. This offers a reliable and indirect way to predict the dielectric constant of nanocrystals.

Ferroelectric inverse opals are promising candidates for tunable photonic crystals due to their electro-optical and elasto-optical properties. In this work, inverse opal photonic crystals of (Pb0.9La0.1)(Zr0.65Ti0.35)O3 (PLZT) were prepared through a self-assembled template replication procedure on a large area (typically 2cm × 1cm). The annealing process was optimized. The surface and cross-section were studied by a scanning electron microscope (SEM). X-ray Diffraction (XRD) results proved that PLZT in the ferroelectric perovskite phase was obtained. A band gap was observed in the transmission spectra and compared with the theoretical value.

Ferroelectric B1 3.25 La 0.75 Ti 3 O 12 (BLT) films and LaAlO 3 (LAO) insulator layers for metal/ferroelectric/insulator/semiconductor structure were first fabricated by chemical solution deposition and pulsed laser deposition. LAO films as a buffer layer show an amorphous structure, a relatively high dielectric constant and good electrical properties. Pt/BLT/LAO/n-Si annealed at 650°C exhibit better hysteretic capacitance-voltage characteristics, with a memory window of 1.3 V and extremely low leakage current density. Furthermore, the memory window does not alter with the sweeping rates of the bias voltage. This implies that the Si surface potential has been controlled by the poling charges of BLT. The introduction of a LAO buffer layer prevents the interfacial diffusion between the BLT and Si substrate effectively. Therefore, BLT/LAO/Si is an attractive candidate for ferroelectric field effect transistor applications.

Bi3.25La0.75Ti3O12 (BLT) thin film has recently been established to be a promising candidate for ferroelectric field effect transistor applications. BLT offers many advantages due to its unique combination of large remnant polarization, low processing temperature, high fatigue resistance and no health or environmental hazard. In this work, we report the characteristics of metal ferroelectric insulator semiconductor (MFIS) structure using chemical solution deposited BLT as the ferroelectric layer. The crystalline BLT films can be achieved by rapid thermal annealing at 650 °C for 180 s. The bismuth layered perovskite structure of BLTx films was confirmed by X-ray diffraction. The films were random oriented either on platinized silicon substrate or on oxidized silicon substrate. The surface morphology was smooth and uniform as recorded by scanning electron microscope. Ferroelectricity of BLT films was revealed by hysteresis measurements using a metal-ferroelectric-metal structure. Memory window and leakage current of Au/BLTx/SiO2/Si MFIS structure were measured and discussed.