Nitride Membrane Research Articles

Molecular landscape on electrosorption improving the desalination performance using a mixed graphene oxide/graphene nitride membrane

Electrosorption is an alternative strategy for seawater desalination, which consist in the effective ions separation from seawater to achieve abundant freshwater. However, the molecular landscape of the electrosorption associated with desalination is not fully understood. In this work, we employ a graphene oxide/graphene nitride (GO/GN) membrane to investigate the role of electrosorption in regulating desalination, accompanied by exposing the corresponding molecular mechanism. Our results show that the electric field is capable of intensifying the adsorption of ions inside the GO and GN sheets interiors that composed the desalination membrane filter. Electrosorption induces the robustly strengthened salt rejection, while mildly interfering with the water permeability, indicating that electrosorption increases the desalination performance by improving the salt rejection capacity of the membrane filter rather than enhancing the water permeability. In addition, by evaluation different values of the interval distance, the interlayer spacing, and the applied electric field, optimal parameters for the desalination process are proposed. Therefore, our study exhibits an in-depth molecular mechanism of the critical electrosorption in advancing desalination performance, which is beneficial for an efficient utilization of electrosorption in future desalination application.

Inhibition of vacuum sublimation artefacts for (Scanning) Transmission Electron Microscopy ((S)TEM) of sulphur samples via encapsulation

Lithium-sulfur battery is one of promising candidates for next-generation energy storage device due to the sulfur cathode material with low cost and nontoxicity, and super high theoretical energy density (nearly 2600Wh kg−1) and specific energy (2567Wh kg−1). Sulphur, however, poses a few interesting challenges before it can gain widespread utilisation. The biggest issue is known as the polysulphide shuttling effect which contributes to rapid capacity loss after cycling. Accurate characterisation of sulphur cathodic materials becomes critical to our understanding polysulphide shuttling effect in the quest of finding mitigating solutions. Electron microscopy is playing a crucial role in battery research in determining structure–property–function relations. However, sulphur undergoes sublimation at a point above the typical pressures found in the column of a transmission electron microscope (TEM) at room temperature. This makes the imaging and characterisation of any sort of nanostructured sulphur samples challenging, as the material will be modified or even disappear rapidly as soon as it is inserted into the TEM vacuum. As a result, materials characterised by such methods are prone to deviation from normal conditions to a great extent. To prevent this, a novel method of encapsulating sulphur particles between silicon nitride (SiNx) membranes is demonstrated in this work.

Molecular Landscape on Electrodialysis Improving the Desalination Performance Using a Mixed Graphene Oxide/Graphene Nitride Membrane

Molecular Landscape on Electrodialysis Improving the Desalination Performance Using a Mixed Graphene Oxide/Graphene Nitride Membrane

Identification of Thermal Barrier Areas in Graphene Oxide/Boron Nitride Membranes by Scanning Thermal Microscopy: Thermal Conductivity Improvement through Membrane Assembling

Two-dimensional (2D) materials are widely accepted as ideal candidates for thermal management materials due to their high intrinsic thermal conductivity and unique anisotropic heat conduction. Theo...

Epitaxial Lift-Off of Flexible GaN-Based HEMT Arrays with Performances Optimization by the Piezotronic Effect

HighlightsA large size (> 2 cm2) nitride membrane with High-electron-mobility transistor (HEMTs) arrays was successfully separated from sapphire substrate onto flexible substrate by an electrochemical lift-off technique.Without adding extra cost, the piezotronic effect is utilized to optimize the electric transport and thermal conductivity properties of the HEMTs by modulating the physical properties of the 2DEG and phonons.This study aims to open up a new way to fabricate high-performance GaN-based HEMTs and expand practical applications in flexible electronics.

A novel shaped-controlled fabrication of nanopore and its applications in quantum electronics

High-intensity (107–108 A m−2) electron beams can be used to fabricate nanoscale pores. This approach enables real-time observation of nanopore drilling and precise control of the diameter of the nanopore. Nevertheless, it is not suitable for tuning the nanopore’s sidewall shape. In this study, we demonstrate the use of low-intensity electron beams to fabricate nanopores on a silicon nitride (SiNx) membrane. This technique allows the precise adjustment of the nanopore dimension and the shaping of its three-dimensional (3D) nanostructure. The 3D structures of the nanopore were evaluated by electron tomography, and series of oblique images were used in reconstructing the 3D images of nanopores using a weighted back-projection method. The sidewall shape of the nanopore was observed at different electron-beam conditions, and the formation mechanism was elucidated based on these results. The nanopore fabricated with this technique can be used as a template to develop electronics at the nanoscale based on which a quantum-dot device can be prepared with a simple evaporation process. The measured results show that the device can resolve well-defined electronic states that are characteristic for the behaviors of the quantum-dot device.

Graphite oxide/boron nitride hybrid membranes: The role of cross-plane laminar bonding for a durable membrane with large water flux and high rejection rate

Swelling of graphene oxide (GO) membrane greatly restricts its use in liquid separation applications. Cross-linking is widely used to stabilize GO membrane but often results in enlarged d-spacing. This work presents a durable hybrid GO/boron nitride membrane with both physical confinement and chemical bonding, which simultaneously achieves large water flux and excellent dye rejection rate. By alternating GO nanosheets and amino-modified boron nitride (a-BN) nanosheets in the hybrid membrane (a-BNGO) structure, plane-plane conformation and edge-edge covalent bonding facilitate the formation of tightly packed laminar structure, which is demonstrated efficient to restrict membrane swelling, improve water flux and methylene blue (MB) separation performance. Specifically, a-BNGO hybrid membranes, with a-BN/GO mass ratio ranging from 1:4 to 2:1, were prepared by pressurized filtration method on top of polydopamine coated polyethersulfone (PDA/PES) substrate. By optimizing the a-BN/GO ratio, high rejection rate of 99.98% and large water flux of 4.15 LMH can be achieved. The separation properties of these membranes were tested stable for up to 9 h, even in different pH conditions (pH = 4–10).

Graphene Stress Transducer-Based Thermo-Mechanically Fractured Micro Valve

This paper presents the design, analysis, and testing of a single-shot thermo-mechanically triggered micromachined micro-valve with graphene on a silicon nitride (Si x N y ) membrane. The graphene serves as a 2-D resistive heater for producing thermo-mechanical stress, to fracture the bilayer formed between nitride and the nickel used to make electrodes. It is demonstrated that the ability of graphene to carry much higher current density per unit than metal heaters enables high thermo-mechanical stress to be generated. The valve is demonstrated as an enabling component of polymer substrate-based vaporizable electronics. It is used for sealing rubidium (Rb) in polymer chambers, and then triggering and exposing it to ambient air to produce heat by exothermic oxidation. This heat energy is used to vaporize the polymers. The nominal valve tested in this work is a $750\,\,\mu \text{m}\,\,\times 750\,\,\mu \text{m}$ membrane of Si x N y . An analytical and finite-element model are presented for the valve, which agree with measured membrane peak-to-peak deflection of $4.1~\mu \text{m}$ just before fracturing, and a peak fracture stress of 395 MPa. The pulsed-power for triggering the valve is nominally 142.1 ± 13.5 mW with a trigger time of 15.4 ± 3.9 ms, resulting in a very low input trigger energy of 2.2 mJ. This trigger energy is $100\times $ lower compared with that of previously reported single-use valves in the literature. [2017–0317]

Fabrication and Modeling of Nitride Thin-Film Encapsulation Based on Anti-Adhesion-Assisted Transfer Technique and Nitride/BCB Bilayer Wrinkling

This paper presents buckled nitride thin-film encapsulation using anti-adhesion layer-assisted transfer technique and benzocyclobutene (BCB)/nitride bilayer wrinkling due to elastic property mismatch between the two attached materials. A 900-nm silicon nitride film is deposited on a Si carrier wafer coated with hydrophobic monolayer, and then nonpatterned nitride film is directly bonded to BCB sealing rings prepared on a target wafer at 250 °C. As bonding and subsequent cooling proceed, shearing force generated by BCB shrinking is applied to the thin nitride film. After bonding, the Si carrier wafer is mechanically separated, leaving only nitride membrane inside BCB ring. Thus, self-patterning and self-alignment have been achieved. Interestingly, most different-size nitride membranes are successfully transferred even though large-size ones have partially collapsed or highly deformed. Also, finite-element method modelings have been carried out to comprehend the formation of the wrinkling of thin elastic film on compliant substrate as well as the debonding of the transfer process of the thin film. It is found that Young's modulus of compliant substrate is significant to the wavelength of the wrinkle and maximum deflection of the buckled film. The debonding may apply substantial force to the elastic film, and thus the nitride membrane needs stabilization time as its shape changes after the debonding.

B12-O-11Development of Self-designed Liquid Holder and Wet-Cell Chips for TEM Applies to Analysis the Precipitation of Calcium Carbonate

Development of “fiber-based light emitting system” integrated with wet cell chips [1] in JEOL 2010F has provided a chance for in-situ observation of the photo-induced catalysis reaction in TEM. Figure1 (a) shows a drawing of the assembly that the optical fiber was used to induce UV light through the EDS pole of JEM-2010. A reflective mirror was installed at the end of fiber which can reflect the incident light onto the sample. The intensity of incident light which penetrates through the glass and the nitride membrane is about 0.1W/cm2. The power is enough for the requirement of experiment. Figure1 (b) shows an in-situ TEM image after Pt deposited on the surface of TiO2 and EDS maps support the evidence that improves the feasibility of the reaction. Figure1 (c) shows TEM images of nanobubble at different period of time. The nano-bubbles keep growing bigger as a function of time.

Molecular Surveillance of Viral Processes Using Silicon Nitride Membranes

Here we present new applications for silicon nitride (SiN) membranes to evaluate biological processes. We determined that 50-nanometer thin films of SiN produced from silicon wafers were sufficiently durable to bind active rotavirus assemblies. A direct comparison of SiN microchips with conventional carbon support films indicated that SiN performs equivalent to the traditional substrate to prepare samples for Electron Microscopy (EM) imaging. Likewise, SiN films coated with Ni-NTA affinity layers concentrated rotavirus particles similarly to affinity-coated carbon films. However, affinity-coated SiN membranes outperformed glow-discharged conventional carbon films 5-fold as indicated by the number of viral particles quantified in EM images. In addition, we were able to recapitulate viral uncoating and transcription mechanisms directed onto the microchip surfaces. EM images of these processes revealed the production of RNA transcripts emerging from active rotavirus complexes. These results were confirmed by the functional incorporation of radiolabeled nucleotides into the nascent RNA transcripts. Collectively, we demonstrate new uses for SiN membranes to perform molecular surveillance on life processes in real-time.

Intracranial MEMS based temozolomide delivery in a 9L rat gliosarcoma model

Primary malignant brain tumors (BT) are the most common and aggressive malignant brain tumor. Treatment of BTs is a daunting task with median survival just at 21 months. Methods of localized delivery have achieved success in treating BT by circumventing the blood brain barrier and achieving high concentrations of therapeutic within the tumor. The capabilities of localized delivery can be enhanced by utilizing mirco-electro-mechanical systems (MEMS) technology to deliver drugs with precise temporal control over release kinetics. An intracranial MEMS based device was developed to deliver the clinically utilized chemotherapeutic temozolomide (TMZ) in a rodent glioma model. The device is a liquid crystalline polymer reservoir, capped by a MEMS microchip. The microchip contains three nitride membranes that can be independently ruptured at any point during or after implantation. The kinetics of TMZ release were validated and quantified in vitro. The safety of implanting the device intracranially was confirmed with preliminary in vivo studies. The impact of TMZ release kinetics was investigated by conducting in vivo studies that compared the effects of drug release rates and timing on animal survival. TMZ delivered from the device was effective at prolonging animal survival in a 9L rodent glioma model. Immunohistological analysis confirmed that TMZ was released in a viable, cytotoxic form. The results from the in vivo efficacy studies indicate that early, rapid delivery of TMZ from the device results in the most prolonged animal survival. The ability to actively control the rate and timing of drug(s) release holds tremendous potential for the treatment of BTs and related diseases.

Sensitivity Features of Thin Film Plate Acoustic Wave Resonators

Thin film plate acoustic resonators devices operating in the lowest order symmetric Lamb wave mode (S0) in c-oriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressure and mass as well as for their ability to work in liquid environment.

Gradient nanoporous structures based on silicon carbide and boron nitride in self-propagating high-temperature synthesis

The paper examines high-temperature corrosion-resistant strong nanoporous structures based on silicon carbide and boron nitride and effective membranes produced from them. The samples made of silicon carbide and boron nitride have the following characteristics: 40–48% and 38% open porosity; 0.05 μm and 0.045 μm pore size; 29 MPa and 19 MPa bending strength; and 0.119 μm 2 and 0.0819 μm 2 gas permeability. Anisotropy is revealed in membranes. It permits using the membranes as gas diodes and as a peculiar storage of gas molecules in the membrane (in particular, hydrogen molecules).

Elemental analysis of nanoparticles via electron beam lithography of patterned arrays on silicon-nitride membranes

I devised a method of electron beam lithography for patterning thin-film silicon- nitride membranes with nanoscale metal arrays of known dimensions. Employing SEM image-based metrology and ellipsometry to determine all three spatial dimensions of the metal nanostructures in the array, the calculated mass of each individual one can be used as a standard for elemental X-ray microanalysis. Thereafter, the net X-ray counts from the patterned nanostructures on a thin silicon-nitride substrate and nanoparticle unknowns can be compared directly for a standards-based quantitative analysis. The minimum mass detectable by this technique is ~10-15 gm, supporting the determination of the absolute mass of nanoparticles with diameters as small as 20 to 30 nm. I then used a JEOL 6500F SEM equipped with a Bruker Quantax XFlash 4030 silicon drift detector (SDD) to assess the absolute masses of nickel nanoparticles contained in agglomerates of single-walled carbon nanotubes.

Ion Impact Detection and Micromapping With a SDRAM for IEEM Diagnostics and Applications

Ion electron emission microscopy (IEEM) can provide an alternative approach to microbeams for micrometric characterization of the sensitivity map to single event effects (SEE) of an electronic device. In IEEM technique, a broad (not focused) ion beam is sent onto the device under test (DUT). Secondary electrons emitted by the target surface during each ion impact are collected and focused by a system of electrostatic lenses and finally imaged by a high-rate and high-resolution position detector. We will report on the IEEM working at the SIRAD irradiation facility located at the 15 MV Tandem of INFN Legnaro National Laboratories. To estimate the IEEM resolution, a SDRAM is a good candidate to be used as a reference target, thanks to the micrometric feature size of the array of memory cells and the precise knowledge of their physical locations. Since an electronic device is not a good secondary electrons emitter, to ensure a copious and uniform emission of secondary electrons from the DUT, a very thin (100 nm) self-standing silicon nitride (Si3N4) membrane with a Au deposition (40 nm) is mounted on the top of the SDRAM. The Au/Si3N4 membrane and the underlying SDRAM are irradiated with a heavy ion beam. The physical map of ion impacts detected by the SDRAM is then compared with the one reconstructed by the IEEM in the same 500 ms time interval.

High throughput Single-Molecule Spectroscopy Using Nanoporous Membranes

We describe a novel approach for optically detecting DNA translocation events through an array of solid-state nanopores that potentially allows for ultra high-throughput, parallel detection at the single-molecule level. The approach functions by electrokinetically driving DNA strands through sub micrometer-sized holes on an aluminum/silicon nitride membrane. During the translocation process, the molecules are confined to the walls of the nanofluidic channels, allowing 100% detection efficiency. Importantly, the opaque aluminum layer acts as an optical barrier between the illuminated region and the analyte reservoir. In these conditions, high-contrast imaging of single-molecule events can be performed. To demonstrate the efficiency of the approach, a 10 pM fluorescently labeled lambda DNA solution was used as a model system to detect simultaneous translocation events using electron multiplying CCD imaging. Single-pore translocation events are also successfully detected using single-point confocal spectroscopy.

Fabrication of nanoporous silicon dioxide/silicon nitride membranes using etched ion track technique

A robust method of fabricating freestanding nanoporous silicon dioxide/silicon nitride membrane on a silicon holder using etched ion track technique was demonstrated in this paper. The basic track etching parameters of silicon dioxide and silicon nitride were studied and appropriate irradiation conditions were obtained. The freestanding membranes were obtained by standard silicon fabrication procedures. The multilayer composite silicon/silicon dioxide/silicon nitride was irradiated by Br ions with fluence of 108–1010cm−2. The latent ion tracks in silicon dioxide were then etched to the silicon nitride layer by aqueous HF solution (4%) to produce conical nanopores. Subsequently, these nanopores in silicon dioxide layer, acting as a mask, were transferred into the silicon nitride layer by reactive ion etching (RIE). Finally, with an extra HF wet etching step, the nanoporous silicon dioxide/silicon nitride membrane can be thinned to nanoporous silicon nitride membrane. The diameter of the nanopores in silicon nitride can be varied by varying the HF wet etching time. Via this method, nanoporous silicon dioxide/silicon nitride membrane with designed pore density and pore diameter of sub 100nm can be achieved.

Single-Molecule Spectroscopy Using Nanoporous Membranes

We describe a novel approach for optically detecting DNA translocation events through an array of solid-state nanopores that potentially allows for ultra high-throughput, parallel detection at the single-molecule level. The approach functions by electrokinetically driving DNA strands through sub micrometer-sized holes on an aluminum/silicon nitride membrane. During the translocation process, the molecules are confined to the walls of the nanofluidic channels, allowing 100% detection efficiency. Importantly, the opaque aluminum layer acts as an optical barrier between the illuminated region and the analyte reservoir. In these conditions, high-contrast imaging of single-molecule events can be performed. To demonstrate the efficiency of the approach, a 10 pM fluorescently labeled lambda-DNA solution was used as a model system to detect simultaneous translocation events using electron multiplying CCD imaging. Single-pore translocation events are also successfully detected using single-point confocal spectroscopy.

A high-temperature thermopile fabrication process for thermal flow sensors

A new high-temperature fabrication process for thermopile-based flow sensors is presented. The high-temperature passivation of LPCVD silicon nitride leads to an improvement for liquid applications because of the low tendency towards pinholes and the good step coverage. The thermopiles are made of p-doped polysilicon and titanium–tungsten (WTi) showing a thermopower of 287 μV K −1 for a single thermocouple. Besides, the nitride membrane was released by a DRIE process to achieve a reduced chip size and higher yield compared to established thermal flow sensors. Devices for different flow rates were fabricated and characterised. A very short reaction time of 2.6 ms could be achieved and the sensors show good sensitivity of 9.5 mV mm −1 s in agreement to the theoretical expectations based on an analytical model.