Hybrid Deposition Method Research Articles

Microstructure forming mechanism of inconel 625 alloy fabricated by laser/ultra-high (UHF) induction hybrid deposition method

To reveal the microstructure forming mechanism of laser/ultra-high frequency (UHF) induction deposition, this paper developed a microscopic phase-field (PF) model to numerically investigate dendrite growth during solidification. The macroscopic model of molten pool evolution is adopted to provide the solidification conditions for the microscopic PF model. The dendrite growth during laser deposition is simulated to evaluate the effect of UHF induction heat on the dendrite growth. Results show that because of the high temperature gradient and cooling rate, the PDAS of laser-UHF induction hybrid deposited layer is less than that of the laser deposited layer. The UHF induction heat also leads to a high flow velocity of the molten metal during laser-UHF induction hybrid deposition. The high flow velocity contributes to the decrease in PDAS by inhibiting the interdendritic enrichment of solute. During laser-UHF induction hybrid deposition, a higher solute gradient is present in the tip region of dendrite arm, leading to a faster dendrite growth rate. The UHF induction heat also increases the solute distribution coefficient during deposition, which further inhibits the element segregation. Under the action of UHF induction heat, a low interdendritic solute gradient and an evenly distributed solute can be obtained, thus helping increase interdendritic undercooling degrees and decreasing the PDAS. The simulated PDAS and solute distribution have good consistency with the experimental results. The spectral analysis of EDS line detection indicates that the laser-UHF induction hybrid deposited layer has a more refined microstructure and weaker element segregation than the laser deposited layer does.

Efficient MAPbI3-based perovskite solar cells exceeding 21% efficiency via aging treatment

Recently, the demand for large-area and high-efficiency perovskite solar cells (PSCs) has increased, and a two-step process for high-efficiency large-area PSCs is actively being studied. However, the two-step process is still less efficient than the one-step antisolvent dripping process owing to the poor interdiffusion of organic components. In this study, a perovskite layer using a hybrid deposition method in which an excess of methylammonium iodide (MAI) solution is reacted with thermally evaporated PbI2 is reported. The perovskite film quality is improved by reacting unreacted residual PbI2 with excess MAI by applying daily electrical stress and aging for 60 days in a glovebox. The best PSC exhibits a PCE of 21.1 %, the highest reported power conversion efficiency among PSCs based on the two-step hybrid deposited MAPbI3 perovskite, with a large enhanced open-circuit voltage of 1.21 V and fill factor of 80.8 %. Moreover, using the solvent pre-heat treatment method, the reaction of unreacted PbI2 with MAI is accelerated, and the aging time of PSCs is shortened from 60 to 7 days, showing a PCE value of 20.7 %. Furthermore, we present a large-area PSC with a PCE of 19.4 %, indicating that the PCE can be improved through the hybrid deposition method.

Microstructure, Wear Resistance and Corrosion Performance of Inconel 625 Layer Fabricated by Laser/Ultra-High Frequency (UHF) Induction Hybrid Deposition

In order to avoid microstructure degradation caused by low frequency induction heat in laser-induction hybrid deposition, this paper proposes a laser/ultra-high frequency (UHF) induction hybrid deposition method. Microstructure observation is carried out to reveal the effect of UHF induction heat on the microstructure of the deposited layer. Results indicate that the laser-UHF induction hybrid deposited layer, under a current density of 1.14 × 108 A/m2, exhibits a finer microstructure and fewer Laves phases than that of the laser deposited layer. As the current density increases from 1.01 × 108 A/m2 to 1.14 × 108 A/m2, the microstructure of the laser-UHF induction hybrid deposited layer is significantly refined; however, as the current density further increases, the microstructure is only slightly further refined, since the enhanced thermal effect, along with the increasing current density, may help grain growth. Wear test demonstrates that the laser-UHF induction hybrid deposited layer obtained with a current density of 1.40 × 108 A/m2 has the lowest average friction coefficient of 0.375 and the lowest wear rate of 15.53 × 10−5 mm3/N·m, indicating a better wear resistance. Corrosion resistance is also evaluated by electrochemical corrosion test. Results indicate that the addition of UHF induction heat improves the corrosion resistance of the deposited layer. Owing to the high ohm resistance of the passive film, the deposited layer fabricated with a current density of 1.01 × 108 A/m2 exhibits the best corrosion resistance. Based on the analysis of wear and corrosion performance, the current density of 1.40 × 108 A/m2 is an optimal parameter for a laser-UHF induction hybrid deposited Inconel 625 layer.

Thermally Stable Nanotwins: New Heights for Cu Mechanics.

Nanocrystalline and nanotwinned materials achieve exceptional strengths through small grain sizes. Due to large areas of crystal interfaces, they are highly susceptible to grain growth and creep deformation, even at ambient temperatures. Here, ultrahigh strength nanotwinned copper microstructures have been stabilized against high temperature exposure while largely retaining electrical conductivity. By incorporating less than 1vol% insoluble tungsten nanoparticles by a novel hybrid deposition method, both the ease of formation and the high temperature stability of nanotwins are dramatically enhanced up to at least 400°C. By avoiding grain coarsening, improved high temperature creep properties arise as the coherent twin boundaries are poor diffusion paths, while some size-based nanotwin strengthening is retained. Such microstructures hold promise for more robust microchip interconnects and stronger electric motor components.

Copper-zinc oxide heterojunction catalysts exhibiting enhanced photocatalytic activity prepared by a hybrid deposition method.

Heterojunction copper–zinc oxide catalysts were prepared by a hybrid two-step methodology comprising hydrothermal growth of ZnO nanorods (ZnO-NR) followed by deposition of Cu2O nanoparticles using an advanced gas deposition technique (AGD). The obtained bicatalysts were characterized by SEM, AFM, XRD, XPS, PL and spectrophotometry and revealed well-dispersed and crystalline Cu2O nanoparticles attached to the ZnO-NR. The adsorption properties and photocatalytic degradation of Orange II dye in water solutions were measured. It was found that the bicatalysts exhibited a conversion rate and quantum yield that both were about 50% higher compared with ZnO-NR alone, which were attributed to the intrinsic electric field created at the p–n junction formed at the Cu2O/ZnO interface facilitating charge separation of electron–hole pairs formed upon interband photon absorption. The interpretation was evidenced by efficient quenching of characteristic deep level ZnO photoluminescence bands and photoelectron core-level energy shifts. By comparisons with known energy levels in Cu2O and ZnO, the effect was found to be most pronounced for the non-polar ZnO-NR side facets, which accounted for about 95% of the exposed surface area of the catalyst and hence the majority of dye adsorption. It was also found that the dye adsorption capacity of the ZnO nanorods increased considerably after Cu2O deposition thereby facilitating the oxidation of the dye. The results imply the possibility of judiciously aligning band edges on structurally controlled and well-connected low-dimensional semiconductor nanostructures using combined two-step synthesis techniques, where in particular vacuum-based techniques such as AGD allow for growth of well-connected nanocrystals with well developed heterojunction interfaces.

Dry-wet hybrid deposition of wide-bandgap mixed-halide perovskites for tandem solar cell applications

The tandem architecture of solar cells is expected to be one of the promising strategies for further improving the performance of photovoltaic devices. While a dry-wet hybrid deposition method is highly promising for fabricating perovskite top cells on textured silicon bottom cells, the bandgap tunability of this deposition method has not been investigated in detail. Here, we show the systematic investigation on mixed-halide perovskite films fabricated by the dry-wet hybrid deposition method on a PbBr2 underlayer. The thermally deposited PbBr2 underlayer is demonstrated to be beneficial for promoting reaction with an organic halide precursor solution, resulting in a dense morphology with large perovskite grains. Furthermore, the hybrid deposition method is also shown to be a straightforward way for wide-range bandgap tuning as it can facilitate halogen mixing. These findings provide useful guidelines for further improving the power conversion efficiency of multijunction tandem solar cell devices.

Mechanical Properties and Vacuum Tribological Performance of Mo-S-N Sputtered Coatings.

MoS2 is the most widely used dry lubricant for low friction applications in vacuum environments. However, due to its lamellar nature it exfoliates during sliding, leading to high wear, high coefficient of friction (COF), and low stability. Here, we report the mechanical properties and the vacuum (10-4 Pa) tribological performance of nitrogen-alloyed transition-metal-dichalcogenide (TMD-N) coatings. The coatings were deposited using a hybrid deposition method, that is, reactive direct current (DC) sputtering of MoS2 target assisted by an additional plasma source. The tribological tests were performed at relatively low contact stresses to replicate real industrial needs. The interaction between different mating surfaces (coating versus steel, coating versus coating) has been reported. Additionally, the effects of loads on the sliding properties were also studied for coating versus coating interactions. A maximum hardness of 8.9 GPa was measured for the 37 atom % N-alloyed coating. In all mating conditions, the pure MoS2 coating had COF in the range of 0.1-0.25 and the least specific wear rates were found to be 3.0 × 10-6 mm3/N·m for flat and 2.5 × 10-6 mm3/N·m for cylinder. As compared to MoS2 coating, the COF and specific wear rates decreased with N additions. The COF was in the range of 0.05-0.1 for Mo-S-N coatings, while coating versus coating displayed the lowest specific wear rates (8.6 × 10-8 mm3/N·m for flat and 4.4 × 10-8 mm3/N·m for cylinder). Finally, the increase in load resulted in a decrease of COF, but an increase in the wear rate was observed. The detailed mechanism behind the behavior of the COF for the different mating conditions was presented and discussed. This work brings some important issues when testing transition metal dichalcogenide-based coatings under low contact stress conditions more appropriate for simulating real service applications.

Interface modification effect on the performance of CsxFA1-xPbIyBr3-y perovskite solar cells fabricated by evaporation/spray-coating method.

In this study, high quality CsxFA1-xPbIyBr3-y perovskite thin films were successfully fabricated by an evaporation/spray-coating hybrid deposition method. In this method, CsI and PbI2 were first deposited via thermal evaporation, and then FAI/FABr mixed solution was sprayed on the CsI/PbI2 substrate to form the CsxFA1-xPbIyBr3-y film. As confirmed by x-ray diffraction, scanning electron microscopy, and atomic force microscopy, a perovskite film with full surface coverage and small surface roughness was obtained. Then, the effect of interface modification materials on the performance of perovskite solar cells (PSCs) was investigated: the devices with the [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) interlayer incorporated via vacuum evaporation deposition between SnO2 and perovskite showed remarkably higher performance than those with the C60 interlayer, which was attributed to enhanced charge extraction and reduced recombination at the SnO2/PCBM/perovskite interface. As a result, a high power conversion efficiency (PCE) of 18.21% was obtained for the 0.16 cm2 device. To the best of our knowledge, it is the highest efficiency of CsxFA1-xPbIyBr3-y based PSCs fabricated by the spray technique. Furthermore, we fabricated mini-modules with the size of 5 × 5 cm2 and achieved a PCE of 14.7%.

New deposition method of MgB2 thin film with thermal evaporation of Mg and sputtering of B

We are now developing a new in situ deposition process for MgB2 film as a candidate method to mass-produce MgB2 thin film superconducting tape. In the new method, a MgB2 film is deposited on a heated metal substrate by a hybrid deposition method, which consists of thermal evaporation of magnesium and sputtering of boron. By using the hybrid deposition method, the substrate temperature can raise from 250 to 350 °C, while its fluctuation is kept less than 1 °C, which will improve the quality and reproducibility of MgB2 film in mass production. The Jc of MgB2 film deposited by the hybrid deposition method at 20 K and self-field was more than 30,000 A mm−2, which was better than the results reported by the two-step in situ process using DC sputtering and 830 °C high-temperature post annealing [] or by the as-grown depostion using sputttering targets of Mg and B []. Although we obtained better Jc than other deposition methods that use sputtering process, the Jc is still lower than the value we obtained by using a co-evaporation method with electron beam (EB). We investigated the film structure and Jc–B–T properties of the film made by the hybrid deposition method and compared them with those of the film made by co-evaporation. From the analysis results, we think the reasons for the lower Jc are the larger amount of heterogeneous phases such as magnesium oxides in the film and the amorphous B phase under the MgB2. We expect to improve the the crystal qualities and superconductivities of the MgB2 film deposited by the new method by removing impurities in Ar gas during sputtering and thinning the B amorphous phase by increasing the Mg deposition rate in the initial stage of deposition.

Fast and sensitive detection of carbaryl pesticide trace by using 2D-arrays of Au and Au/Ag core/shell nanoparticles

We report on (i) the synthesis of monodisperse Au and Au-core/Ag-shell nanoparticles (NPs) with controllability of the Au-core in the range of 20–50 nm and fixing the thickness of the Ag shell of ∼20 nm, and (ii) the arrangement of two-dimensional (2D) arrays of Au core and Au-core/Ag-shell NPs on the 1 cm2 ITO substrates. Various Au NPs with uniform size-distribution were synthesised by seed-mediated growth method at ambient conditions. All synthesised 2D-arrays with homogeneous and dense monolayers of NPs (coverage ∼85%) were prepared by hybrid deposition method based on the mixed n-alkanethiolate self-assembled monolayer. We have used the fabricated 2D-arrays from the 20-nm Au-core/Ag-shell NPs as a surface-enhanced Raman scattering (SERS) substrate to take the Raman scattering spectra of carbaryl pesticide at very low concentration of 0.01 ppm.

Field-Effect Transistors Based on 2D Organic Semiconductors Developed by a Hybrid Deposition Method.

Solution‐processed 2D organic semiconductors (OSCs) have drawn considerable attention because of their novel applications from flexible optoelectronics to biosensors. However, obtaining well‐oriented sheets of 2D organic materials with low defect density still poses a challenge. Here, a highly crystallized 2,9‐didecyldinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (C10‐DNTT) monolayer crystal with large‐area uniformity is obtained by an ultraslow shearing (USS) method and its growth pattern shows a kinetic Wulff's construction supported by theoretical calculations of surface energies. The resulting seamless and highly crystalline monolayers are then used as templates for thermally depositing another C10‐DNTT ultrathin top‐up film. The organic thin films deposited by this hybrid approach show an interesting coherence structure with a copied molecular orientation of the templating crystal. The organic field‐effect transistors developed by these hybrid C10‐DNTT films exhibit improved carrier mobility of 14.7 cm2 V−1 s−1 as compared with 7.3 cm2 V−1 s−1 achieved by pure thermal evaporation (100% improvement) and 2.8 cm2 V−1 s−1 achieved by solution sheared monolayer C10‐DNTT. This work establishes a simple yet effective approach for fabricating high‐performance and low‐cost electronics on a large scale.

Influence of carbon incorporation on microstructure and properties of titanium diboride coatings deposited by combining ion beam with magnetron sputtering

Titanium diboride (TiB2) coatings with carbon incorporation were deposited by a hybrid deposition method consisted of an ion beam and a pulsed magnetron sputtering using a gas mixture of acetylene (C2H2) and argon (Ar). The influence of carbon incorporation on composition, microstructure, mechanical properties and high temperature oxidation behavior of the TiB2 coatings was investigated using scanning electron micrograph, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, nanoindentation and Thermogravimetric analyzer as a function of the added carbon content. The results indicate that the carbon content of the coatings increases from 0 to 24.0 at. % as the C2H2 flow fraction increases from 0 to 10% in the C2H2/Ar gas mixture. It is found that the incorporated carbon atoms tend to form B–C bonds and exist mainly as an amorphous B–C phase in the coatings when the addition content of the carbon is relatively high. The amorphous B–C phases can refine the TiB2 grains and encapsulate the TiB2 grains to build nanocomposite structures, significantly improving the mechanical properties of the TiB2 coatings. In addition, the amorphous phases can make the TiB2 grains isolate oxygen and improve the oxidation resistance of the TiB2 coatings.

Smooth perovskite thin films and efficient perovskite solar cells prepared by the hybrid deposition method

The hybrid deposition method was developed to overcome the difficulties that the vacuum-based techniques face for fabricating perovskite solar cells. Our results provide an explanation of various factors that need optimizing to achieve convenient and reliable fabrication of large-area smooth perovskite thin films for solar cell applications without the use of solvents.

Simulation and fabrication of SiO2/graded-index TiO2 antireflection coating for triple-junction GaAs solar cells by using the hybrid deposition process

GaAs-based multi-junction solar cells (MJ-SCs) provide a wide solar-energy absorption-band (300–1800nm), but designing and fabricating a broadband antireflection coating (ARC) are challenging. Because MJ-SCs are typically in a series that connects each subcell, the total output current is limited by the subcell that generates the smallest photocurrent. Thus, the ARC for MJ-SCs must be designed not only to obtain broadband absorption but also to minimize light reflection at the wavelength band of the current-limited cell. This study proposes a broadband SiO2/graded-index TiO2 ARC for improving the current-limited subcell performance by using a hybrid deposition (e-beam evaporation and spin-on coating). A bottom TiO2 layer and a top SiO2 layer were deposited through e-beam evaporation, but the middle TiO2 layer was deposited using spin-on coating because the refractive index values of the TiO2 films could be tuned by applying the spin speed. Therefore, the graded-index TiO2 layers were easily obtained using a hybrid deposition method. In addition, a suitable reflectance spectrum of an ARC structure for a middle-cell current-limited triple-junction (3-J) GaAs solar cell was simulated using commercial optical software. The photovoltaic current–voltage and external quantum efficiency (EQE) were measured and compared. The resulting improvements of a short-circuit current of 32.4% and conversion efficiency of 31.8% were attributed to an enhanced EQE of 32.97% as well as a low broadband reflectance exhibited on the middle cell of the 3-J GaAs solar cell with a SiO2/graded-index TiO2 ARC.

Square-centimeter-scale 2D-arrays of Au@Ag core–shell nanoparticles towards practical SERS substrates with enhancement factor of 107

A series of two-dimensional (2D) arrays of Au-core/Ag-shell nanoparticles with fixed sub-3nm gap distance was obtained on 1cm2 substrates. All 2D arrays resulted in homogeneous and dense monolayers of nanoparticles thanks to our original hybrid deposition method based on self-assembly. Midnanosized gold nanoparticles were used as the core and Ag-shell with different thicknesses were grown to tune the LSPR to around 633nm. The resulting SERS substrates enhanced Raman signal by up to about 107 with remarkable spatial uniformity. Our SERS substrate is highly promising as a practical SERS-based sensor substrate.

Fabrication of semi-transparent perovskite films with centimeter-scale superior uniformity by the hybrid deposition method

We report the development of instrumentation and methodology for fabricating large area semi-transparent organo-lead-halide perovskite films. In our method, the growth of perovskite films relies on the control of CH3NH3I flow and vapor pressure inside a vacuum chamber. Solar cell devices based on the prepared semi-transparent perovskite films as thin as ∼135 nm achieved an efficiency of 9.9% and a high open circuit voltage of 1.09 V.

Influence of Vacuum Cathodic Arc Etching on Structure and Properties of W-Doped DLC Films

In order to further improve the deposition process of the W-doped DLC films synthesized by a hybrid deposition method of vacuum cathodic arc, ion beam deposition, and magnetron sputtering, the paper studied the effect of vacuum cathodic arc etching prior to the deposition on the surface morphology, chemical bond status, hardness, elastic modulus, adhesion, friction, and wear of the films. It was found that the surface defects in the W-doped DLC films, which increase the average value and fluctuation of the friction coefficient of the W-doped DLC films, are mainly produced by vacuum cathodic arc etching. The adhesion and wear resistance of the W-doped DLC films can be obviously improved by arc etching while arc etching has an unobvious effect on the chemical bonding status, hardness, and elastic modulus of the W-doped DLC films.

The Formation of Diamond-Like Carbon Film at Atmospheric Pressure by the Pulsed Laser/Plasma Hybrid Deposition Method

A pulsed laser/plasma hybrid deposition method has been developed to produce the diamond-like carbon (DLC) film at atmospheric pressure in this work. A plasma torch was used to heat up the carbon particles which were simultaneously ablated by a pulsed laser, thus the kinetic energy of the carbon particle can be increased to form the carbon atoms with amorphous bonding structure of the DLC film. The influences of the plasma flow have been examined at various inlet pressures. According to the experimental results of the carbon film inspected by the Raman spectroscopy, it reveals that the intensity ratio of the D-band to G-band of the carbon film can be reduced to 0.5 by the implementation of plasma flow. Therefore the DLC film was solidly formed. The adhesive strength of the DLC film was also characterized by the scratch test, it can be found that the critical loading of the film on the iron substrate is up to 19 N.

Synthesis and properties of CrN x/amorphous-WC nanocomposites prepared using hybrid arc ion plating and direct current magnetron sputtering

Hybrid deposition method was used to prepare CrN x/amorphous-WC (CrN x/a-WC) films. The effect of the arc ion plating and direct current magnetron sputtering on the changes in microstructure and properties such as hardness and thermal stability were studied. The amorphous WC phase of the CrN x/a-WC films was confirmed by X-ray photoelectron spectroscopy and high resolution transmission electron microscopy. A bi-phase nanocomposite kinetic model and the Koehler's theory were used to explain the growth mechanism of CrN x/a-WC films. A superhard superlattice Cr 2N/a-WC film with hardness up to ~ 48 GPa was abtained. The CrN/a-WC films displayed better resistance to oxidation than pure CrN and CrN-based films. As such, CrN x/a-WC nanocomposite films are very promising for high-speed drying machines and other high-temperature applications.

The formation of diamond-like carbon film at atmospheric pressure by the pulsed laser/plasma hybrid deposition method

A pulsed laser/plasma hybrid deposition method has been developed to produce the diamond-like carbon (DLC) film at atmospheric pressure in this work. A plasma torch was used to heat up the carbon particles which were simultaneously ablated by a pulsed laser, thus the kinetic energy of the carbon particle can be increased to form the carbon atoms with amorphous bonding structure of the DLC film by this proposed hybrid deposition method. The influences of the plasma flow have been examined numerically and experimentally. In the numerical analysis, the temperatures of the plasma flow at various inlet pressures and electrode currents have been predicted. According to the experimental results of the carbon film inspected by the Raman spectroscopy, it reveals that the intensity ratio of the D-band to G-band of the carbon film can be reduced to 0.5 by the implementation of plasma flow. Therefore the DLC film was solidly formed. The adhesive strength of the DLC film was also characterized by the scratch test, it can be found that the critical loading of the film is up to 19 N.