Showing papers on "Barrier layer published in 2022"
TL;DR: In this article , a high quality barrier layer of a Ni-based alloy has been fabricated on both n-type and p-type Bi2Te3-based TE legs by the electroplating method.
Abstract: The barrier layer between thermoelectric (TE) legs and electrodes has crucial impact on the electrothermal conversion efficiency of the TE device; however, the interfacial reaction of the Ni metal barrier layer with TE legs in traditional Bi2Te3-based devices is harmful to the device performance. Herein, a high-quality barrier layer of a Ni-based alloy has been fabricated on both n-type and p-type Bi2Te3-based TE legs by the electroplating method. The in situ XRD results indicate that the as-prepared Bi2Te3-based TE legs with a Ni-based alloy barrier layer remain stable even at 300 °C. The high-resolution high-angle annular dark field scanning transmission electron microscopy images reveal that the Ni-based alloy barrier layer has more excellent stability than that of the Ni metal barrier layer. The Bi2Te3-based TE devices with excellent structural and performance stabilities were assembled with the as-grown high-performance n-type and p-type Bi2Te3-based leg with a Ni-based alloy barrier layer, which have lower internal resistance and higher cooling and power generation performances. A maximum cooling temperature difference over 65 K and a maximum cooling capacity of 55 W were obtained for the high-performance Bi2Te3-based TE devices. This work provides a new strategy for high-temperature applications of commercial Bi2Te3-based TE devices.
12 citations
TL;DR: In this paper , a new type of 10%ZrB2 + 5%YSZ-modified Si-Mo-18%W coating with a boride diffusion barrier was prepared by a novel three-step method.
12 citations
TL;DR: In this paper, a new type of 10%ZrB2 + 5%YSZ-modified Si-Mo-18%W coating with a boride diffusion barrier was prepared by a novel three-step method.
12 citations
TL;DR: In this paper, Ta2O5 thin film with different thicknesses (2, 4, and 6 nm) was exploited as an appropriate interfacial barrier layer for limiting the formation of the interfacial layer between the 10 nm thick sputtering deposited resistive switching (RS) layer and Ta ohmic electrode to improve the switching cycle endurance and uniformity.
12 citations
TL;DR: In this paper, a series of Mo films, as the infrared reflective layer, were deposited on stainless steel (SS) or glass substrates by DC magnetron sputtering, and the effects of sputtering parameters on crystal structure, surface morphologies, film resistivity, and infrared emissivity of the Mo films were systematically investigated.
11 citations
TL;DR: In this article , the sintering and steam corrosion behavior of Yb2Si2O7 with and without the addition of Al2O3 has been studied on compacted specimens.
9 citations
TL;DR: In this paper , a typical porous anodic aluminum oxide (PAAO) film consisting of an outer porous layer and inner hemispherical barrier layer, which is based on the Keller-Hunter-Robinson (KHR) model, was formed in acidic solutions.
6 citations
TL;DR: The effect of the GaN cap layer on the performance of AlInN/GaN-based HEMTs has been studied in this article , where the authors have observed a slight increase in the two-dimensional electron gas density on the addition of the GAs.
6 citations
TL;DR: In this article , the authors focus on the use of sputtered indium tin oxide (ITO) as a barrier layer to stop major degradations of planar perovskite solar cells.
Abstract: The commercialization of perovskite solar cells (PSCs) requires the development of long-term, highly operational-stable devices. An efficient barrier layer plays a key role in improving the device stability of planar PSCs. Here, we focus on the use of sputtered indium tin oxide (ITO) as a barrier layer to stop major degradations. To mitigate efficiency losses of cells with the ITO barrier, we optimized various sputtering process parameters such as ITO layer thickness, target power density, and working pressure. The fabricated planar inverted PSCs based on the novel ITO barrier optimization demonstrate a power conversion efficiency (PCE) of 19.05% on a cell area of 0.09 cm2. The encapsulated cells retained >80% of their initial efficiency after 1400 h of continuous illumination at 55 °C and 94.5% of their initial PCE after 1500 h stored in air. Employing such a holistic stabilization approach, the PSC minimodules without encapsulation achieved an efficiency of 16.4% with a designated area of 2.28 cm2 and retained approximately 80% of the initial performance after thermal stress at 85 °C for 350 h under ambient conditions.
5 citations
TL;DR: In this article, a mechanically induced artificial potential barrier (MIAPB) is set up by a pair of tensile/compressive stresses acted on a piezoelectric PN junction.
4 citations
TL;DR: In this article , a mechanically induced artificial potential barrier (MIAPB) is set up by a pair of tensile/compressive stresses acted on a piezoelectric PN junction.
TL;DR: In this article , a novel diffusion barrier of electrodeposited CoWP layer was developed in order to solve the interconnection failure caused by the diffusion between copper and silicon in electrical circuit.
TL;DR: In this paper , an aluminum nitride (AlN) quasi-vertical Schottky barrier diode (SBD) was fabricated on an AlN bulk substrate and the epitaxial AlN layer was etched down to the n-Al0.9Ga0.1N layer to form an Ohmic contact.
Abstract: An aluminum nitride (AlN) quasi-vertical Schottky barrier diode (SBD) was fabricated on an AlN bulk substrate. An undoped AlN layer, a Si-doped Al0.9Ga0.1N current spreading layer and an AlN buffer layer were grown by plasma-enhanced molecular beam epitaxy. The epitaxial AlN layer was etched down to the n-Al0.9Ga0.1N layer to form an Ohmic contact. Ni/Au and V/Al/Ni/Au were deposited on the top AlN layer as Schottky contacts and on the exposed n-Al0.9Ga0.1N layer as Ohmic contacts, respectively. The Ohmic characteristics on the n-Al0.9Ga0.1N layer, capacitance–voltage (C–V) and current–voltage (I–V) characteristics of the AlN SBD were investigated.
TL;DR: In this paper , the effect of the tungsten nitride diffusion barrier layer on the resistive switching operation of the aluminum nitride (AlN) based conductive bridge random access memory was investigated.
Abstract: In this work, we investigated the effect of the tungsten nitride (WNx) diffusion barrier layer on the resistive switching operation of the aluminum nitride (AlN) based conductive bridge random access memory. The WNx barrier layer limits the diffusion of Cu ions in the AlN switching layer, hence controlling the formation of metallic conductive filament in the host layer. The device operated at a very low operating voltage with a Vset of 0.6 V and a Vreset of 0.4 V. The spatial and temporal switching variability were reduced significantly by inserting a barrier layer. The worst-case coefficient of variations (σ/µ) for HRS and LRS are 33% and 18%, respectively, when barrier layer devices are deployed, compared to 167% and 33% when the barrier layer is not present. With a barrier layer, the device exhibits data retention behavior for more than 104 s at 120 °C, whereas without a barrier layer, the device fails after 103 s. The device demonstrated synaptic behavior with long-term potentiation/depression (LTP/LTD) for 30 epochs by stimulating with a train of identical optimized pulses of 1 µs duration.
TL;DR: In this article , an ultra-high frequency (≥10 kHz) was employed to produce plasma electrolytic oxidation (PEO) upon the surface of Mg-8Gd-3Y-0.5Zr alloy to understand its mechanistic contribution to the growth of PEO.
Abstract: Ultra-high frequency (≥10 kHz) was employed to produce plasma electrolytic oxidation (PEO) upon the surface of Mg-8Gd-3Y-0.5Zr alloy (GW83, in wt%) to understand its mechanistic contribution to the growth of PEO. The maximal pore area of the resulting PEO coatings was reduced by about one order of magnitude when frequency was increased from 0.5 kHz (65.8 μm2) to 20 kHz (7.1 μm2), which is attributed to the ten times reduction in single pulse energy. Cross-sectional SEM micrographs and electrochemical impedance spectroscopy confirm that the PEO coatings obtained at low frequency (i.e. 0.5 and 5 kHz) were consisted of an inner barrier layer and an outer porous layer, while ultra-high frequency PEO coatings were divided into three distinct layers: an inner barrier layer, an intermediate compact layer, and an outer porous layer. Moreover, thickness of the effective corrosion barrier layer of PEO coating including inner barrier layer and intermediate compact layer increased as a function of frequency, resulting in high corrosion resistance of the ultra-high frequency PEO coating. Those findings are anticipated to provide new insights to guide design and preparation of high-quality PEO coatings to tackle corrosion challenges of Mg alloys.
TL;DR: In this article , a surface charge-regulated layer-by-layer assembly of polyelectrolyte multilayers (PEM) was proposed for the deposition of barrier layers inside microchannels using a surface-chargeregulated layer by layer assembly of PEM.
Abstract: Recently, there has been an increasing demand for developing high performance barrier films for effectively suppressing the penetration of organic solvent. Particularly, in microfluidic systems for lab-on-a-chip devices or inkjet printing, the predominantly faced challenges are swelling deformation and channel blockage by the penetrated solvents, which significantly deteriorates the device performance and lifetime. To address this issue, here we present a robust method for the deposition of barrier layers inside microchannels using a surface charge-regulated layer-by-layer assembly of polyelectrolyte multilayers (PEM). Owing to the highly negative surface charge and additionally employed crosslinking reaction using glutaraldehyde (GA), the Donnan repulsion at the barrier film surface and size-narrowing effect in internal pores can be simultaneously intensified, which rendered excellent barrier performance against highly penetrating organic solvents only with a 14-nm-thick coating layer. Further, we employed a wrinkling-based metrology for precisely evaluating the barrier property of the multilayered films. As a result, highly negatively charged PEM surface (−64.2 mV) with small inner pores (<0.5 nm) resulted in excellent barrier performance to the penetration of various conventional organic solvents used for microelectronic processing. Finally, the practical applicability of the PEM barrier films coated in complexly structured microchannels was demonstrated by fully securing the devices intact even under continuous exposure to organic solvent flowing for 4 h. As such, this study provides a general guideline for the internal deposition of barrier films regardless of the form factor of target surfaces toward next generation organic and wearable electronic devices, along with microfluidic chemical reactor systems.
TL;DR: In this paper , a simple approach to control the nucleation of Si nanowires via interfacial energy tuning between metal catalysts and substrates by introducing a conductive diffusion barrier was developed.
Abstract: Uniform size of Si nanowires (NWs) is highly desirable to enhance the performance of Si NW-based lithium-ion batteries. To achieve a narrow size distribution of Si NWs, the formation of bulk-like Si structures such as islands and chunks needs to be inhibited during nucleation and growth of Si NWs. We developed a simple approach to control the nucleation of Si NWs via interfacial energy tuning between metal catalysts and substrates by introducing a conductive diffusion barrier. Owing to the high interfacial energy between Au and TiN, agglomeration of Au nanoparticle catalysts was restrained on a TiN layer which induced the formation of small Au nanoparticle catalysts on TiN-coated substrates. The resulting Au catalysts led to the nucleation and growth of Si NWs on the TiN layer with higher number density and direct integration of the Si NWs onto current collectors without the formation of bulk-like Si structures. The lithium-ion battery anodes based on Si NWs grown on TiN-coated current collectors showed improved specific gravimetric capacities (>30%) for various charging rates and enhanced capacity retention up to 500 cycles of charging–discharging.
TL;DR: In this article , a conformal amorphous carbon (a•C) layer with a thickness of 1−nm−level is tested as a possible Cu diffusion barrier layer for next-generation ultrahigh-density semiconductor device miniaturization.
Abstract: A reliable method for preparing a conformal amorphous carbon (a‐C) layer with a thickness of 1‐nm‐level, is tested as a possible Cu diffusion barrier layer for next‐generation ultrahigh‐density semiconductor device miniaturization. A polystyrene brush of uniform thickness is grafted onto 4‐inch SiO2/Si wafer substrates with “self‐limiting” chemistry favoring such a uniform layer. UV crosslinking and subsequent carbonization transforms this polymer film into an ultrathin a‐C layer without pinholes or hillocks. The uniform coating of nonplanar regions or surfaces is also possible. The Cu diffusion “blocking ability” is evaluated by time‐dependent dielectric breakdown (TDDB) tests using a metal−oxide−semiconductor (MOS) capacitor structure. A 0.82 nm‐thick a‐C barrier gives TDDB lifetimes 3.3× longer than that obtained using the conventional 1.0 nm‐thick TaNx diffusion barrier. In addition, this exceptionally uniform ultrathin polymer and a‐C film layers hold promise for selective ion permeable membranes, electrically and thermally insulating films in electronics, slits of angstrom‐scale thickness, and, when appropriately functionalized, as a robust ultrathin coating with many other potential applications.
TL;DR: In this paper , the hemispherical barrier oxide layer (BOL) closing the bottom tips of hexagonally distributed arrays of cylindrical nanochannels in nanoporous anodic alumina (NAA) membranes is structurally engineered by anodizing aluminum substrates in three distinct acid electrolytes at their corresponding self-ordering anodic potentials.
Abstract: The hemispherical barrier oxide layer (BOL) closing the bottom tips of hexagonally distributed arrays of cylindrical nanochannels in nanoporous anodic alumina (NAA) membranes is structurally engineered by anodizing aluminum substrates in three distinct acid electrolytes at their corresponding self-ordering anodizing potentials. These nanochannels display a characteristic ionic current rectification (ICR) signal between high and low ionic conduction states, which is determined by the thickness and chemical composition of the BOL and the pH of the ionic electrolyte solution. The rectification efficiency of the ionic current associated with the flow of ions across the anodic BOL increases with its thickness, under optimal pH conditions. The inner surface of the nanopores in NAA membranes was chemically modified with thiol-terminated functional molecules. The resultant NAA-based iontronic system provides a model platform to selectively detect gold metal ions (Au3+) by harnessing dynamic ICR signal shifts as the core sensing principle. The sensitivity of the system is proportional to the thickness of the barrier oxide layer, where NAA membranes produced in phosphoric acid at 195 V with a BOL thickness of 232 ± 6 nm achieve the highest sensitivity and low limit of detection in the sub-picomolar range. This study provides exciting opportunities to engineer NAA structures with tailorable ICR signals for specific applications across iontronic sensing and other nanofluidic disciplines.
TL;DR: In this article , a non-planar growth approach was proposed to enable the deposition of crack-free high-Al-mole-fraction AlxGa1−xN on patterned GaN/sapphire templates and bulk GaN substrates with large-area mesas.
Abstract: Wide-bandgap III-nitride heterostructures are required for a variety of device applications. However, this alloy system has a large lattice constant and thermal expansion coefficient mismatch that limits the alloy composition and layer thickness for many heteroepitaxial device structures. Consequently, various methods have been devised to allow the heteroepitaxial growth of AlInGaN heterostructures to accommodate this inherent strain. In this work, we describe a non-planar-growth approach that enables the deposition of crack-free high-Al-mole-fraction AlxGa1−xN on patterned GaN/sapphire templates and bulk GaN substrates with large-area mesas. We have studied the effects of the patterned mesa width, the mesa etch depth, and the gap between the mesas on the heteroepitaxy of AlxGa1−xN superlattices with an average Al molar fraction 0.11 < x¯ < 0.21 and non-planar overgrowth growth thicknesses up to 3.5 μm. Similar to the planar growth approach, increasing the thickness and Al mole fraction of the AlxGa1−xN superlattices leads to surface cracking when exceeding the critical layer thickness. However, limiting the mesa dimension in one direction enables strain mitigation and drastically increases the critical layer thickness. Additionally, larger etch depths of the mesas increase the Al alloy composition and thickness for crack-free AlGaN heteroepitaxy whereas the gap in between the mesas seems to have no crucial influence. We demonstrate that the Al alloy composition and layer thicknesses of such heterostructures can be increased far beyond the critical layer thickness for planar growth and demonstrate the growth of a crack-free full AlxGa1−xN/GaN quantum-well laser heterostructure designed for operation at ∼370 nm.
TL;DR: In this paper , the impact of the graded AlGaN back barrier and Fe-C co-doping buffer structure on the high electron mobility transistors (HEMTs) was investigated and systematically investigated.
Abstract: In this article, the impact of the graded AlGaN back barrier and Fe\C co-doping buffer structure on the AlGaN $/$ GaN high electron mobility transistors (HEMTs) is proposed and systematically investigated. Due to effective suppression of Fe tail in unintentionally doped GaN (uid-GaN) layer by the insertion of the thick graded AlGaN back barrier layer, a large maximum drain current density and a transconductance peak are achieved. Meanwhile, the breakdown voltage is significantly improved by the use of Fe\C co-doping GaN buffer design. More importantly, it is revealed that the graded-AlGaN design can reduce the range and intensity of the electrical potential distribution in uid-GaN layer and then effectively suppress the acceptor-induced trapping\detrapping effect under high drain voltage. The RF small-signal performance of Fe-doped GaN (GaN:Fe)\C co-doping buffer HEMT exhibits significant improvement. In addition, load-pull measurement at 8 GHz revealed that a saturation power increases from 38.04 to 41.07 dB, a power gain increases from 9.06 to 10.58 dB, and an associate power-added-efficiency (PAE) increased from 40.27% to 50.18%. Our proposed GaN-based epitaxial structure can not only suppress the gate lag by reduce AlGaN surface electric field, but it can also suppress the drain lag by reduce the amplitude and range of potential distribution. It indicates that our proposed device has great potential for future high-voltage RF power amplifier application.
TL;DR: In this paper , the degradation of GaN-InGaN MQW solar cells with different thickness of the p-GaN layer to constant power stress at 310 W/cm2, 175 °C for several hundred hours was analyzed.
TL;DR: In this paper, a dual layer dual layer coating was applied to SUS 430 steel via multi-arc ion plating and magnetron sputtering in sequence for use of solid oxide fuel cell (SOFC) interconnects.
TL;DR: In this paper , anodic and spontaneous corrosion of different types of stainless steel (AISI 304L, AISI 316L and 2205 DSS) in phosphate-buffered saline solution (PBS, pH = 7.4) at 37 °C were examined using open circuit potential measurements, linear and cyclic polarization, and electrochemical impedance spectroscopy methods.
Abstract: Anodic and spontaneous corrosion of different types of stainless steel (AISI 304L, AISI 316L and 2205 DSS) in phosphate-buffered saline solution (PBS, pH = 7.4) at 37 °C (i.e., in simulated physiological solution in the human body) were examined using open circuit potential measurements, linear and cyclic polarization, and electrochemical impedance spectroscopy methods. After the anodic and spontaneous corrosion, the surface of the tested samples was investigated by light and scanning electron microscopy (SEM) with EDS analysis. It has been established that the tendency of the examined steel materials towards local corrosion decreases in the order: AISI 304L < AISI 316L < 2205 DSS. Namely, the possibility of repassivation and the resistance to local corrosion increases in the same order. The corrosion resistance of steel samples at open circuit potential is a consequence of forming a natural oxide film with a bi-layer structure and consists of an inner barrier and an outer porous film. The inner barrier film has a small thickness and extremely high resistance, while the outer porous film is much thicker but also has significantly lower resistance. The inner barrier layer mainly prevents corrosion of examined steel samples in order: AISI 304L < AISI 316L < 2205 DSS. Light microscopy and SEM/EDS analysis after pitting and spontaneous corrosion showed damage on the AISI 304L and AISI 316L surface, while the surface of 2205 DSS was almost undamaged by corrosion.
TL;DR: In this paper , three potential regions were distinguished throughout the reverse scan polarization of AAO layers in sulfuric acid, thanks to voltammetry and in situ electrochemical impedance spectroscopy (EIS) studies performed in a threeelectrode cell.
TL;DR: In this article , a thermodynamic design for a self-forming barrier that provides reliability with Co interconnects is presented, where Cr diffused into the dielectric interface and reacted with oxygen to provide a selfforming diffusion barrier comprising Cr2O3.
Abstract: With recent rapid increases in Cu resistivity, RC delay has become an important issue again. Co, which has a low electron mean free path, is being studied as beyond Cu metal and is expected to minimize this increase in resistivity. However, extrinsic time-dependent dielectric breakdown has been reported for Co interconnects. Therefore, it is necessary to apply a diffusion barrier, such as the Ta/TaN system, to increase interconnect lifetimes. In addition, an ultrathin diffusion barrier should be formed to occupy as little area as possible. This study provides a thermodynamic design for a self-forming barrier that provides reliability with Co interconnects. Since Cr, Mn, Sn, and Zn dopants exhibited surface diffusion or interfacial stable phases, the model constituted an effective alloy design. In the Co-Cr alloy, Cr diffused into the dielectric interface and reacted with oxygen to provide a self-forming diffusion barrier comprising Cr2O3. In a breakdown voltage test, the Co-Cr alloy showed a breakdown voltage more than 200% higher than that of pure Co. The 1.2 nm ultrathin Cr2O3 self-forming barrier will replace the current bilayer barrier system and contribute greatly to lowering the RC delay. It will realize high-performance Co interconnects with robust reliability in the future.
TL;DR: In this paper , a pull-off adhesion testing method was adopted to separate the corrosion products for weathering steel layer-by-layer, and the Ni element makes the rust layer compact, improves the adhesion strength, and forms a physical barrier.
TL;DR: In this paper , a multi-layer barrier coating technology was developed using nano-fibrillated cellulose (NFC) alongside a hydrophobic, paraffin-free biowax for manufacturing an eco-friendly functional packaging paper.
Abstract: A multi-layer barrier coating technology was developed using nano-fibrillated cellulose (NFC) alongside a hydrophobic, paraffin-free biowax for manufacturing an eco-friendly functional packaging paper. Anionic NFC was prepared by isolating hardwood-bleached kraft pulp (Hw-BKP) using a micro-grinder, and cationic NFC was prepared by the quaternization reaction of the anionic NFC. Thereafter, a three-layer barrier-coated paper was manufactured using cationic and anionic NFCs and biowax. The air permeability and water vapor transmission rate (WVTR) of the three-layer barrier-coated paper were measured, and its coverage and coating layer structure were observed by scanning electron microscopy (SEM). The air permeability of the three-layer barrier-coated paper was more than 15,000 s and those WVTR was 67.1 g/m2/day. Its coverage and surface were considerably uniform and smooth. Thick and effective barrier coating layers were formed as indicated by SEM images. Therefore, it was concluded that a multi-layer barrier-coated paper with considerably high barrier properties could be produced using cationic and anionic NFCs with high gas barrier properties and biowax with high moisture barrier properties. Further, the structure could be used as a functional packaging paper with high barrier properties.