Effect Of Buffer Layer Research Articles

Effect of an agglomeration-suppressed metal island buffer layer on nanostructure of FePt-oxide granular films for heat assisted magnetic recording media

Effect of an agglomeration-suppressed metal island buffer layer on nanostructure of FePt-oxide granular films for heat assisted magnetic recording media

Optoelectronic effect of Al-based buffer layers on Al-doped ZnO thin transparent conductive films on flexible substrates

AZO (Al-doped ZnO) film is a transparent conductive film that offers a simple preparation process, low cost, non-toxicity, and excellent stability. It serves as a high-quality material extensively used in liquid crystal displays, solar cells, and other fields. In this study, AZO thin films were prepared on a PET substrate with an Al2O3 buffer layer using the magnetron sputtering method. The deposition parameters were optimized through the Taguchi method and Grey Correlation Analysis. The results demonstrate that the optimal deposition parameters for achieving superior photoelectric properties during the fabrication of AZO films are 100 W (radio frequency power), 1.0 Pa (sputtering pressure), 20 min (coating time), and 20 °C (substrate temperature). Furthermore, the incorporation of an Al2O3 buffer layer enhances the quality of AZO film on PET substrate. This investigation successfully deposited uniform and highly efficient AZO thin films onto flexible PET substrates at low temperatures, thereby expanding their potential applications in flexible electronics.

Single Layer of Crown Ether Enables Efficient, Stable, and Pb Leakage-Free Inverted Perovskite Solar Cells.

Significant challenges in ensuring long-term stability, addressing environmental safety issues, and improving efficiency have hindered the commercialization of inverted Pb-based halide perovskite solar cells (PeSCs). One reasonable approach to addressing these issues is to place an effective buffer layer between the perovskite active layer and the electrode. In this study, we demonstrate the use of crown ether, di-tert-butyl dibenzo-18-crown-6, as a single buffer layer to improve the efficiency, long-term stability, and environmental safety of PeSCs for the first time. The crown ether buffer layer suppressed Ag diffusion from the Ag metal electrodes, thereby improving the performance and lifetime of the device. In addition, it effectively captures Pb ions that may leak into the environment during the whole lifetime of devices, thereby enhancing the environmental safety of PeSCs. Furthermore, PeSCs incorporating crown ethers as buffer layers demonstrated enhanced stability in a nitrogen atmosphere and achieved a high power conversion efficiency of 22.8%. Consequently, this crown ether buffer layer offers an effective and straightforward strategy capable of achieving efficient, stable, and environmentally safe PeSCs.

Effect of p-type doped buffer layer on the structural and magnetic properties of (Zn,Fe)Te dilute magnetic semiconductor

Effect of p-type doped buffer layer on the structural and magnetic properties of (Zn,Fe)Te dilute magnetic semiconductor

Exploring Structural Features and Growth Mechanisms in GdBa2Cu3O7-x /LaFeO3 Bilayers on SrTiO3 Substrates.

This study investigated a novel approach to enhance the performance of superconductors by applying a LaFeO3 (LFO) buffer layer on a GdBa2Cu3O7-x (GdBCO) superconducting thin film. LFO is a rare-earth orthoferrite (REFO) materials. The objective was to assess how the thickness of the LFO layer influences the superconducting properties of the GdBCO material. LFO layers were fabricated at thicknesses of 50, 100, 150, and 200 nm, and subsequently, a 200 nm thick layer of GdBCO was deposited to create a bilayer structure. This study represents the first utilization of a REFO material, specifically LFO, as a buffer layer, with findings showing its growth in a pseudocubic structure. We thoroughly examined the characteristics of LFO, including its structural, surface, and strain states, focusing on the impact of varying layer thicknesses. Additionally, we investigated changes within the GdBCO/LFO bilayer and analyzed how LFO influences the properties of GdBCO. It was found that the application of the LFO buffer layer by varying thicknesses not only provided structural compatibility with GdBCO but also consistently resulted in the improvement of its superconducting transition temperature, as evidenced by the enhanced Tc-onset values reaching up to 92.4 K with an LFO thickness of 150 nm. These findings reveal significant potential in utilizing REFO materials, particularly those derived from LFO, as effective buffer layers in superconductor applications.

An Acceptor–Donor–Acceptor Molecule Tailored Versatile Buffer Enabling Efficient and Stable Perovskite Solar Cells

AbstractInterface in perovskite solar cells (PSCs) is of vital importance because it dominates deep‐level defects and non‐radiative recombination, thus impacting both efficiency and stability further. Herein, a symmetrical acceptor–donor–acceptor (A–D–A) conjugated molecule with the core architecture of terthieno[3,2‐b hiophene and 2‐(3‐oxo‐2,3‐dihydro‐1 H‐inden‐1‐ylidene)malononitrile, named 6TIC, as a versatile buffer layer, is adopted to enhance photovoltaic performance and stability simultaneously. It is found that the conjugated molecule filling at grain boundaries and surface can not only chemically anchor with perovskite components to substantially eliminate interfacial defects and suppress detestable non‐radiative recombination, but also effectively improve the energy level alignment and facilitate charge transfer efficiency at the interface, resulting in an excellent power conversion efficiency of 24.81% with an admirable fill factor of 84.5%. Furthermore, benefiting from the unexceptionable surface protection effect of the hydrophobic buffer layer, greatly improved operational stability is delivered, with retaining 90% of initial efficiency for 960 h aging in a relative humidity of 60 ± 5% air and 1450 h aging under continuous 85 °C heating stress. This strategy may provide a new avenue for advancing high‐efficiency and stable PSCs.

Optimized InGaAs growth on GaP/Si(1 0 0) templates with different low-temperature layers

In this paper, the effect of low-temperature buffer layer on the quality of InGaAs grown on GaP/Si templates is investigated. Three different materials, InP, GaAs/InAs and InAs/InP, were grown on GaP/Si templates by molecular beam epitaxy (MBE). The interfacial states between the above materials and the GaP layer were calculated using first principles methods. It was found that the interfacial structure formed with the InAs/InP material was the most robust due to the shorter bond lengths and stronger interaction forces between the interfaces. Theoretical calculations are in agreement with the experimental results that the InGaAs grown using the InAs/InP digital alloy structure as a low temperature buffer layer has the best material quality.

CHTS/Zn2P3-based solar cells with enhanced efficiency through ETL engineering: A numerical study

Copper Mercury Tin Sulfide (CHTS) solar cells have shown a promising performance in the field of photovoltaic energy conversion with a bandgap range between 1.0 eV and 1.5 eV. However, further improvement is required to enhance the efficiency of CHTS SCs. In our study, we conducted Numerical simulation of the investigation of the effect of different buffer layers and a Zn2P3 back-surface field (BSF) layer on the effectiveness of CHTS SCs using the SCAPS-1D Programming. Initially, we optimized the basic structure of a CHTS SC without a BSF layer. We evaluated three different buffer layers (GaN, In0.4Ga0.6N, and In0.65Ga0.35N) as potential insulating layers. GaN was found to be the optimal buffer strata, with a power conversion efficiency (PCE) of 19.89%. Next, we proposed a new device structure with a Zn2P3 BSF layer. The BSF layer was found to have a positive effect on cell effectiveness, increasing the PCE to 21.16%. We further investigated the effect of different input variables, such as carrier concentration, fault density, and thickness of the absorbed strata on the achievement of both apparatus structures, with and without the BSF layer. Our results showed that the device structure with the Zn2P3 BSF layer achieved a maximum PCE of 23.79%, which is significantly higher than the PCE of the apparatus structure in case of the absence of the BSF strata. This improvement in PCE is due to the reduced reassemble of the charge transporters behind the interface and the improved light absorption in the CHTS layer. Overall, our numeral conclusion suggests that the use of CHTS/GaN-based solar photovoltaic cell design with a Zn2P3. The BSF layer is considered an ideal choice for high-performance solar cells (SCs).

Effect of High Al Content AlGaN Buffer Layer on the Properties of GaN‐on‐Silicon Materials

The lattice parameter and thermal expansion coefficient mismatch between the silicon substrate and GaN lead to high tensile stress, which makes the GaN epitaxial layer prone to cracking. Effective compensation of tensile stress on GaN to prevent cracking is an important issue in GaN epitaxial growth. In this work, GaN‐on‐silicon materials with different AlGaN buffer layer structures are prepared by metal‐organic chemical vapor deposition (MOCVD). The GaN epitaxial material with a smooth and crack‐free surface is fabricated by inserting 7 AlGaN buffer layers. The crystal quality of GaN is characterized using high resolution X‐ray diffraction (HRXRD). The full‐width half maximum (FWHM) value of GaN(002) and GaN(102) crystal plane is 398 and 780 arcsec, respectively. The surface root mean square (RMS) roughness of GaN material is 0.31 nm, and the vertical breakdown voltage (BV) of the epitaxial wafer reaches 918 V. The results show that high Al content of the AlGaN buffer layer can effectively reduce the tensile stress and dislocation density of the GaN layer when the entire AlGaN layer thickness remains constant. Suppressing the generation of surface cracks and improving the crystal quality can improve the vertical breakdown voltage and two‐dimensional electron gas (2‐DEG) characteristics of GaN epitaxial wafers.

Enhanced photoconversion efficiency of Cu2MnSnS4 solar cells by Sn-/Zn-based oxides and chalcogenides buffer and electron transport layers

Copper Manganese Tin Sulfide, Cu2MnSnS4 (CMTS), has emerged as a potential candidate for cost-competitive, eco-friendly single- or multiple p-n junction kesterite quaternary photovoltaics (PVs) due to its distinct optical and electrical properties, with earth-abundant as well as non-toxic constituents. In this article, Cu2MnSnS4 absorber-based heterostructures with ZnMgO, WS2, SnO2, CdS electron transport (window) and SnS2, ZnSe, ZnSnO, Zn(O,S) buffer layers have been investigated by executing a systematic study and proposing the mostly efficient device structures containing the favourable band alignment using the SCAPS-1D simulator. Initially, an effective buffer and electron transport (window) layers have been optimized from Al:ZnO/window (ZnMgO, WS2, SnS2, or CdS)/buffer (SnS2, ZnSe, ZnSnO, Zn(O,S))/Cu2MnSnS4/Pt structures. Subsequently, the impact of different properties of each active layer of optimized structures, such as bandgap, layer thickness, carrier concentration, bulk and interface defect densities, and working temperature, was determined by measuring PV parameters and corresponding quantum efficiency. The present study exhibited the maximum photocurrent, JSC of 23.69 mA/cm2, open circuit voltage, VOC of 1.236 V, fill factor, FF of 85.49% and photoconversion efficiency, PCE of 25.03% with optimized SLG/Mo/Cu2MnSnS4/SnS2/ZnMgO/ZnO:Al/Pt structure under AM1.5G irradiation. Furthermore, a detailed comparison among recent studies has been carried out to demonstrate the significance of the proposed structure, challenges, and future prospects. Thus, obtained results pave significant resources and emancipate a new pathway to fabricate enviro-benign, cost-competitive, high-efficiency CMTS-thin film photovoltaics.

Effect of two-step cubic GaN buffer layer on the radio-frequency plasma-assisted molecular beam epitaxy growth of cubic AlN films grown on MgO (001) substrates

Cubic AlN (c-AlN) films were grown on MgO (001) substrates through the use of a two-step cubic GaN (c-GaN) buffer layer using radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE) technique. The two-step c-GaN buffer layer was found to be crucial for the epitaxial growth of c-AlN, as it showed a specific epitaxial relationship between c-AlN and c-GaN along the MgO [100] zone axis. On the other hand, the c-AlN films grown with the one-step and nonGaN buffer layers showed columnar grain structure. The optical study found that the c-AlN films grown with the two-step c-GaN buffer layer had an indirect bandgap energy of 4.99 ± 0.02 eV, which is consistent with previous experimental data and theoretical calculations. The c-AlN films grown with the one-step and nonGaN buffer layers had indirect bandgap energies of 5.00 ± 0.02 eV and 5.18 ± 0.02 eV, respectively. These results highlight the importance of the two-step c-GaN buffer layer in enhancing the MBE growth of c-AlN on MgO (001) substrate.

A New Strategy: Achieving High-Performed SOCs Using Sonic-Spraying as an Advanced Manufacturing

Many studies have been reported for not only efficient production of hydrogen via SOECs but also high performed SOFCs, and La1-xSrxGa1-yMgyO3-δ (LSGM), a substitute for yttria-stabilized zirconia (YSZ) has emerged as a rising candidate for the electrolyte due to its superior ionic conductivity even in intermediate temperature (≤1073K). Since solid oxide electrochemical devices with LSGM can work in intermediate temperatures, it can have better durability and efficiency at lower temperature operating conditions. However, a few essential requirements must still be addresses for the widespread use of commercial LSGM based electrochemical device; their lower mechanical strengths and higher reactivity with electrode compared to the YSZ based electrolyte makes it difficult to find a cost-effective manufacturing process and compatible materials. In this regard, several strategies for advanced manufacturing have been carried for competitive commercialization of LSGM based SOCs at KICET: (a) lowering temperature processing, (b) ultra-thinner self-standing electrolyte, (c) non-touchable electrode coating processing, and (d) optimal buffer layer. Our innovative activity on the recent LSGM based SOCs will be discussed in detail.Consequently, the fabricated cell exhibits outstanding maximum power density of 1.40 W cm-2 with the ohmic resistance of 0.131 Ω cm2 at 1073K through the effects of the thinner buffer layer and modified electrode surface via the simple-step sonic spraying technique. When the higher electrolysis performance was, subsequently, achieved on reverse SOC operation mode; a high current density of 1.01 A cm-2 at 1073 K, when applied 1.3 V. Fig. (a) The cell performance using nano CMF decorated LSCM cathode on (a) fuel cell (H2 fuel) Figure 1

Effect of TaN buffer layer on the sensitivity of ASIC-integrated AMR sensors

This study investigates the impact of a TaN buffer layer on the performance of ASIC-integrated Anisotropic Magnetoresistive (AMR) position sensors. Our findings demonstrate that the inclusion of a TaN buffer layer significantly enhances the sensitivity and stability of the sensors, with a measured sensitivity of 0.678 ± 0.03 Gauss/mV. In contrast, devices without the buffer layer exhibit a notable decline in sensitivity, decreasing to 0.165 ± 0.02 Gauss/mV after 450℃ annealing. In addition, AMR sensors fabricated on non-ASIC substrates showed no such deterioration. Magneto-optical Kerr effect (MOKE) measurements reveal that the change in sensitivity is primarily attributed to variations in the anisotropy field. We propose that the increased anisotropy field is a result of magnetostatic energy induced by alterations in the PECVD-deposited SiO2 surface granular structure, supported by surface morphology characterization and X-ray diffraction experiments. These findings highlight the critical role of the TaN buffer layer in optimizing the performance and stability of ASIC-integrated AMR sensors.

Effects of Buffer Layer on Structural Properties of Nonpolar (112¯0)-Plane GaN Film

Nonpolar (112¯0) a-plane GaN films were grown on semipolar (11¯02) r-plane sapphire substrates using various buffer layers within a low-pressure metal organic chemical vapor deposition system. The structural properties of nonpolar a-plane GaN films were intensively investigated by X-ray diffraction and Raman spectra measurements. A set of buffer layers were adopted from a GaN layer to a composite layer containing a multiple AlN layers and a gradually varied-Al-content AlGaN layer, the full width at half maximum of the X-ray rocking curves measured along the [0001] and [101¯0] directions of a-plane GaN were reduced by 35% and 37%, respectively. It was also found that the basal-plane stacking faults (BSFs) density can be effectively reduced by the heterogeneous interface introduced together with the composite buffer layer. An order of magnitude reduction in BSFs density, as low as 2.95 × 104 cm−1, and a pit-free surface morphology were achieved for the a-plane GaN film grown with the composite buffer layer, which is promising for the development of nonpolar GaN-based devices in the future.

3D Carbon Coating Enabled High‐capacity and Stable Micro‐sized Silicon Suboxide‐graphite Blended Anodes for Practical Lithium‐ion Batteries

AbstractSilicon oxide (SiOx) is a promising anode candidate of lithium‐ion batteries (LIBs) owing to its extremely high specific capacity. However, the low initial Coulombic efficiency (ICE) and rapid capacity degradation of SiOx, triggered by the enormous volume variation upon repeated (de)lithiation, gravely hinder its practical use. Herein, two mass‐produced micro‐sized SiOx@C composites with obviously different morphologies for commercial LIBs are reported. Particularly, the SiOx‐graphite blended anode (SiOx@3D‐G‐Gr) based on SiOx wrapped by three‐dimensional (3D) carbon layers (SiOx@3D‐G) exhibits a capacity of 519 mAh g−1, an ICE of 90.0 % and a capacity retention of 83.4 % at 0.2 C over 100 cycles. which is far exceeding its counterpart SiOx@C‐H‐Gr (65.7 %). The obtained impressive properties of SiOx@3D‐G originate from the critical contribution of 3D carbon layers, which serves as the effective stress buffer and protective layer as well as the strong networks for electron/Li+ transport. Accordingly, the full‐cell based on SiOx@3D‐G‐Gr anode and commercial LiCoO2 cathode delivers a capacity of 803 mAh and an excellent capacity retention of 95.6 % (616 mAh, 96.6 % for graphite, respectively) at 1 C over 100 cycles with a stabilized CE of nearly 100 %. The micro‐sized SiOx@3D‐G showing a promising prospect in the commercial‐grade anodes in LIBs.

Influence of Pulse Atomic-Layer Epitaxy (PALE) AlN Buffer Layer on Quality of MOCVD Grown GaN on Si(111) Substrate.

A crack-free GaN-on-Si with a high capability to grow a thick GaN layer is important for the performance of optoelectronic devices. Regrettably, a large lattice and thermal mismatch degraded the quality of GaN-on-Si. Therefore, we introduce the pulse atomic-layer epitaxy (PALE) AlN buffer layer to overcome the surface crack issues and improve the quality of GaN epilayers. The effect of PALE AlN buffer layer with 0, 35, 70, and 140 cycle numbers towards the quality of grown GaN on Si(111) substrate is studied. All samples have been observed using AFM, FESEM, XRD and Raman spectroscopy. AFM imaging revealed a fully-coalesced and clear step flow GaN layer with the lowest RMS roughness of 0.606 nm. FESEM surface morphology shows a crack occurs on a sample without AlN PALE (0 pulse cycle) while crack-free GaN is obtained for samples with AlN PALE layer (35, 70 and 140 cycles). It was observed by XRD that the AlN PALE pulse cycle number greatly affects the structural properties of the top GaN layer where the lowest x-ray rocking curve for (002) and (102) achieved at 70 cycles, indicating the reduction of threading dislocations density in the growth structure. Further, the transition of the GaN E2 (high) from the Raman spectroscopy revealed a tensile strain in the GaN epilayers reduces with the increasing number of pulse cycles.

Investigation of Cap and Buffer Layer Effect in Co/Ni Thin Films by Ferromagnetic Resonance Technique

In this study, the magnetic properties of Si(100)/X5/(Co0.3/Ni0.5)3/Y5 (X: Pt, Cu and Y: Pt, Cu, all thicknesses are nm) multilayers were investigated using ferromagnetic resonance technique (FMR). In sample sets all layers (buffer, cap, and Co) were grown by magnetron sputtering while Ni sub-layers were grown by molecular beam epitaxy (MBE) at high vacuum. The effective magnetic anisotropy is 300 mT when copper is used as the buffer and cap layer, 290 mT when the buffer layer is copper, and the cap layer is Pt. On the other hand, it is seen that the effective magnetic anisotropy is 350 mT when Pt is used as buffer and cap layer, and 150 mT when Pt buffer and Cu cap layer are used. Furthermore, magnetic easy axis is out of plane when the Pt buffer layer is used, while the magnetic easy axis is parallel to the plane when the Cu buffer layer is used. The results show that the buffer and cap layers of Co/Ni thin films, which are frequently used in the field of spintronics influence the magnetic properties.

Visualization of dynamic phase mixing and equilibrium process in transcritical and supercritical conditions

The phase mixing and equilibrium process plays a crucial role in the energy cycle and fuel process of supercritical fluids. This study focuses on the dynamic phase mixing during equilibrium process. The transient high-precision measurement of the density field during the phase mixing and equilibrium process is realized by the phase-shifting interferometer based on the pixelated-array masked method. The slow density equilibrium between four typical phase transition routes is captured and quantified with the visualization images and local parameters. The interface spreading rate during the equilibrium between liquid and supercritical is at a rather high level as 0.82 mm/s on average. This phenomenon is controlled by mixing and diffusion, which are faster process than evaporation. Nevertheless, equilibrium can be retarded even in a supercritical environment during the phase mixing between liquid-like and gas-like crossing the pseudo-critical line (average value of interface spreading rate as 0.45 mm/s), where there is a significant density gradient that generates a “solid wall” (buffer layer) effect.

Experimental Study on the Effect of Buffer Layer on the Explosive Drive of Reactive Fragment

In order to study the influence of the buffer layer on the explosive drive of the reactive fragment, for the reactive fragment warhead of the same structure, the warhead static explosion test and the break-through target test method were used to test the fragment integrity and the fragment integrity of the reactive fragment warhead of the reactive fragment warhead with several different thickness silicone rubber buffer layers. The initial velocity of the fragment was measured, and its integrity and the variation law of the initial velocity were analyzed. The results show that with the increase of the thickness of the buffer layer, the integrity of the reactive fragments increases. When the thickness of the buffer layer is 2 mm, the fragment integrity rate is zero, and when the thickness of the buffer layer is greater than 8 mm, the integrity rate is greater than 0.85. The difference in the initial velocity of the warhead of the same reactive fragment is small, mainly because with the increase of the thickness of the buffer layer, the initial velocity of the fragment decreases mainly because the loading ratio of the warhead decreases; the buffer layer has a significant effect on reducing the initial velocity of the reactive fragment, and k=0.83 can be used The modified Gurney formula was used to estimate the initial velocity of the reactive fragments of the silicone rubber buffer layer.

Dynamic centrifuge test of shield tunnels with non-water reacting two-component polymer buffer layer

A buffer layer is one of the countermeasures to promote the anti-seismic performance of tunnels. A newly invented non-water reacting two-component polymer (NRTCP) is superior in impermeability and durability. The construction process of the NRTCP is time-saving and labor-saving. In this study, in order to verify the seismic isolation efficiency of the NRTCP around a shield tunnel model, a dynamic centrifuge test with several dynamic input signals was conducted. The seismic responses of shield tunnel models with and without the NRTCP layer were compared. The results show that the bending moments of the tunnel model with an NRTCP layer were lower than those without an NRTCP layer. Thus, this indicates that the NRTCP layer positively reduced the bending moment in the tunnel model. The axial strain in the tunnel model with the NRTCP layer was lower than that without the NRTCP layer. In addition, the frequency contents of the acceleration response of the tunnel models were rarely influenced by the NRTCP layer. These findings demonstrated the positive effects of the NRTCP buffer layer on seismic isolation in shield tunnels.