Conventional Physical Vapor Deposition Research Articles

Treelike PS-PVD coating: Hierarchical branching by shading and sintering

A structure zone model (SZM) with columnar structures for conventional physical vapor deposition (PVD) has been assigned to plasma spray-physical vapor deposition (PS-PVD) coatings. However, many different comprehensive properties between PS-PVD and conventional PVD coatings reveal the essential different microstructures. In this work, an impact-diffusion model was established based on the impact and diffusion behavior of depositing units. The microstructure formation of PS-PVD coatings was simulated. Results clearly display that the PS-PVD coating shows a novel treelike structure with hierarchical branches rather than a well-known columnar structure. The hierarchical branching is determined by the shadowing effect. Besides, temperature-promoting diffusion of vapor units can generate the in-situ sintering of the coatings. In-situ sintering happens during the deposition process and can govern the branching behavior. A novel treelike SZM is established as an enlargement of the conventional one, marked by successive transformations in branching and densifying. The treelike SZM is experimentally proved by the electron microscopy images and mechanical properties of typical PS-PVD YSZ coatings.

Grain engineering of solution-processed Sb2S3 thin film by tuning precursor fabrication environments

Antimony sulfide (Sb2S3) has garnered significant attention recently due to its remarkable photovoltaic properties and low toxicity. However, the conventional physical vapor deposition approach faces challenges in achieving high-quality films due to Sb2S3 having a quasi-one-dimensional nanoribbon structure. In contrast, solution-processed Sb2S3 thin films have shown improved photovoltaic behavior, offering a low-cost and scalable fabrication method. Nonetheless, the sensitivity of the solution process to the chemical composition of the precursor poses a challenge, often requiring noble gas protection to prevent exposure to toxic solvents or moisture-sensitive chemicals. Despite this, the impact of precursor fabrication conditions on film growth behavior remains unexplored. In our study, we investigate how different processing atmospheres of precursors, namely nitrogen (N2) and air, affect grain growth and the associated optical and electronic performance of Sb2S3 thin films. Our findings reveal that the presence of oxygen in the precursor can hinder grain growth by obstructing surface integration sites, resulting in undesired (hk0) orientation and even the formation of Sb2O3 on the surface of the Sb2S3 films, despite identical post-deposition conditions. This research sheds light on how the ambient conditions during precursor preparation can influence grain engineering, thereby providing valuable insights for controlling the grain size and producing high-quality Sb2S3 absorber films.

Thermal stability of thick α- and γ-Al2O3 coatings deposited by high-speed PVD

α- and γ-Al2O3 coatings, are often used for high temperature applications T ≥ 800 °C. While stable α-Al2O3 is typically synthesized by chemical vapor deposition (CVD) due to its high formation temperature T ≥ 1000 °C, conventional physical vapor deposition (PVD) is limited to T ≈ 600 °C. Nevertheless, this method may result in metastable or amorphous Al2O3 phases, which limits their thermal stability and application at higher temperatures. Previous studies showed that High-Speed PVD can synthesize thick α- and γ-Al2O3 coatings at T ≈ 780 °C. This study investigates the thermal stability of these coatings deposited by HS-PVD. High-temperature X-ray diffraction (HT-XRD) measurements show no phase transformations of coatings up to T = 1200 °C in a vacuum or atmosphere. The coating morphology remained unchanged, and no cracks were detected by scanning electron microscopy (SEM) after annealing during HT-XRD. In situ, HT nanoindentation (HT-NI) revealed a reduction in indentation hardness of X ≈ 33 % and Y ≈ 40 % at THT-NI = 650 °C and THT-NI = 750 °C, respectively. However, hardness values remained similar to the as-deposited state after annealing in HT-XRD. These findings reveal a high thermal stability of crystalline Al2O3 coatings deposited by HS-PVD up to T = 1200 °C, which can extend the application of these coatings to higher temperatures.

Surface evolution of Pt/MoO3/4H-SiC(0001) investigated by in situ near-ambient pressure X-ray photoelectron spectroscopy

Achieving effective Ohmic contact between SiC and metal electrodes remains a challenge due to the high Schottky barrier resulting from the large mismatch between the deep-lying valence band of SiC and Fermi level of metals. One promising approach to address this issue is to introduce a high-work-function interfacial layer between the metal and semiconductor. However, the interaction mechanisms of the inserted high-work-function interfacial layer between metal electrodes and the SiC substrate have been rarely studied systematically. In this work, layers of high-work-function molybdenum trioxide (MoO3) and platinum (Pt) were successively grown on the 4H-SiC(0001) surface via conventional physical vapour deposition (PVD). We investigated the chemical and electronic structure evolutions upon Pt deposition on MoO3/4H-SiC(0001) using in situ near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and ultraviolet photoelectron spectroscopy (UPS). Subsequently, the evolutions of Pt/MoO3/4H-SiC(0001) system during annealing under ultra-high vacuum (UHV) or various gas phase environments (H2 and O2) were studied via in situ NAP-XPS and UPS. Our results reveal that Pt showed its thermal stability during the annealing process, while Mo presented its versatile chemical characteristics. These results depict a detailed chemical feature of the Pt/MoO3/4H-SiC(0001) system and help gain a better understanding about the impact of different environments on Pt/MoO3 interface.

Synthesis and mechanical properties of co-deposited W nanoparticle and ZrCuAg metallic glass thin film composites

The combination of conventional physical vapor deposition and a gas aggregation nanoparticle source enabled the study of model systems of unique material combinations and dimensions. Zr50Cu45Ag5 thin film metallic glasses with varying contents of single-crystalline 5 nm tungsten nanoparticles were synthesized using this technique. This approach provides precise control over nanoparticle shape, size, distribution, and concentration. The films were later annealed at 150 °C, 250 °C, 350 °C, and 450 °C.At room temperature inclusion of 0.01 vol% tungsten nanoparticles caused a 15% increase in the nanoindentation hardness of a thin film metallic glass, while having no significant effect on pop-in length or frequency, as seen in the loading curves. Even more remarkably, at 450 °C a control film containing no nanoparticles experienced significant segregation and subsequent crystallization, whereas this effect was repressed in the tungsten nanoparticle composite thin film metallic glass. Unobstructed by nanoparticles, at high temperatures zirconium diffused to the surface of the film, forming a crystalline layer of up to 80 nm. In contrast, this layer is kept to below 30 nm when the nanoparticles are present. The stabilization of the microstructure is also clear from indentation results, while the hardness of the reference sample changes significantly due to the undesired crystallization, the hardness of the composite remains constant.

Van Der Waals Metal Contacts for Electronic and Optoelectronic Devices

For the fabrication of thin-film electronics, conventional physical vapor deposition (PVD) processes have been widely used to form metal contacts on various thin films. However, the PVD process, involving thermally activated high-energy metal atoms, damages the underlying thin films, severely deteriorating the performance and stability of the device. The van der Waals (vdW) metal-contact approach has recently emerged to avoid this issue. By transferring predeposited metal contacts using vdW interactions, atomically sharp and electronically clean heterointerfaces can be formed without generating unintended defects. In this article, we review the fundamentals, processes, and various applications of the vdW metal-integration approach. The classical theory of vdW interactions is first reviewed, followed by the introduction of various approaches for constructing vdW metal contacts on thin films. Subsequently, the influence of contact configuration on the performance of various applications is summarized. Finally, the remaining challenges and prospects are discussed for the practical usage and versatile application of vdW metal contacts for next-generation electronic devices.

Facile fabrication of multifunctional transparent electrodes via spray deposition of indium-tin-oxide nanoparticles

Low-dimensional nanomaterials with various functionalities are highly promising materials for transparent electrodes which are key components of electronic and optoelectronic devices. However, conventional physical vapor deposition (PVD) methods are not applicable to low-dimensional nanomaterials because of the harsh vaporizing conditions, and using solution processing technologies as alternatives is attracting attention. Herein, we demonstrate a facile method for fabricating of multifunctional transparent electrodes via one-step spray deposition of indium-tin-oxide (ITO) nanoparticles. In this method, ITO nanoparticles are spontaneously and rapidly packed, forming electrically conductive thin films composed of random nanostructures. This method can be adapted to fabricating hierarchical structures, that is, micropatterns consisting of random nanostructures, using impermeable shadow masks. In addition, the optical and electrochemical properties of the spray-deposited ITO films were investigated to confirm their high transmission haze values and ion-storage capabilities, leading to further applications such as random scattering layers, transparent superconductors, and high-performance electrochromic devices. We expect these results to spur the development and refinement of multifunctional electrodes and their electronic and optoelectronic applications.

Wafer scale synthesis of organic semiconductor nanosheets for van der Waals heterojunction devices

Organic semiconductors (OSC) are widely used for consumer electronic products owing to their attractive properties such as flexibility and low production cost. Atomically thin transition metal dichalcogenides (TMDs) are another class of emerging materials with superior electronic and optical properties. Integrating them into van der Waals (vdW) heterostructures provides an opportunity to harness the advantages of both material systems. However, building such heterojunctions by conventional physical vapor deposition (PVD) of OSCs is challenging, since the growth is disrupted due to limited diffusion of the molecules on the TMD surface. Here we report wafer-scale (3-inch) fabrication of transferable OSC nanosheets with thickness down to 15 nm, which enable the realization of heterojunction devices. By controlled dissolution of a poly(acrylic acid) film, on which the OSC films were grown by PVD, they can be released and transferred onto arbitrary substrates. OSC crystal quality and optical anisotropy are preserved during the transfer process. By transferring OSC nanosheets (p-type) onto prefabricated electrodes and TMD monolayers (n-type), we fabricate and characterize various electronic devices including unipolar, ambipolar and antiambipolar field-effect transistors. Such vdW p-n heterojunction devices open up a wide range of possible applications ranging from ultrafast photodetectors to conformal electronics.

Nanoscale Ag/WO3 Multilayered Fabry–Perot Cavities for Colorimetric NO2 Sensing

High-performance gas sensors with low operating temperatures are of emerging research interest. They do not require heaters, thus guaranteeing cost-effectiveness and low power consumption. This is a study to demonstrate the possibility of fabricating a high-performance sensor through a simplified mechanism based on the surface property changes of a Fabry–Perot cavity. Here, the upper metal reacts independently, allowing accurate analyses to be performed while minimizing errors due to external factors. The proposed sensor rapidly responds to corrosive gases; it shifts the absorption wavelength by over 45 nm, that is, from 552 to 597 nm within 15 min at room temperature, significantly changes the color from purple to blue, and can be fabricated in bulk using conventional electron-beam physical vapor deposition. NO2 gas experiments verify the sensor’s superior performance and productivity potential, demonstrating its applicability in urban areas and factories.

Impact Resistance and Properties of (Cr,Al,Si)N Coatings Deposited by Gas Flow Sputtering with Pulsed DC Supply

To increase the erosion and corrosion resistance of compressor blades, hard (Cr,Al,Si)N coatings are used. Physical vapor deposition (PVD) is a well‐known method for the deposition of nitride hard coatings. The application of pulse technique in power supply of conventional PVD technologies like magnetron sputtering shows a great potential for increasing the durability and lifetime of different tools and components. However, one disadvantage of conventional PVD is the line‐of‐sight characteristic. This is eliminated by means of the convection‐driven transport mechanism in high speed physical vapor deposition (HS‐PVD) technology, based on gas flow sputtering. Herein, the influence of gas flow sputtering with bipolar pulsed direct current (DC) power supply on coating properties and impact resistance of (Cr,Al,Si)N/substrate compound is investigated. Thereby, (Cr,Al,Si)N coatings are deposited onto X3CrNiMo13‐4 by HS‐PVD using continuous DC and bipolar pulsed DC supply. Nanoindentation analyses show an increase in indentation hardness using pulsed DC compared with continuous DC. Moreover, the lowest imprint depth and degree of cohesive and adhesive failures are observed in this case. These release a high potential for pulsed power supply in HS‐PVD, resulting in denser morphology, higher hardness and impact resistance compared with DC.

Demonstration of Resistive Pt Temperature Sensors Directly Printed Using Novel Atomic-Layer 3D Printer

This case study demonstrates resistive Pt temperature sensors fabricated by a novel Atomic Layer 3D-printer, a revolutionary rapid prototyping tool utilizing a combination of atomic layer deposition (ALD), microfluidics and high precision 3D printing [1], first time introduced at AVS ALD 2020 [2], and also discussed in detail in the ECS 2021 G01 symposium [3]. The printed sensors are characterized and compared to a thin film sensor made using conventional (physical vapor deposition, lithography) methods and also to a Pt100 standard.ALD works like a chemical vapor deposition (CVD) but the precursors react with the substrate one at a time, in a sequential, self-limiting manner, offering thickness control on the level of atomic layers. Combining ALD and 3D printing, the Atomic Layer 3D-printer allows for deposition of thin films with controllable thickness in the sub-nm range in a pre-programmed X-Y pattern, with no need for lithography or additional patterning, on a wide variety of substrates.The printer nozzle moves relative to the substrate in a highly controlled manner (in this case ~2 mm/s). The nozzle is a miniature spatial ALD system where the precursor (MeCpPtMe3 in this case) flows out of the center of the nozzle, surrounded by a concentric rings of vacuum and a reactant gas, in this case ozone (O3). The result is an area-selective ALD, where each nozzle pass over the substrate equals to one ALD cycle, with a typical deposition rate of ~0.9 nm/cycle.In this study, resistive Pt temperature sensors were fabricated on the SiO2/Si substrates by printing >2 mm long Pt-wires of different thicknesses (approx. range 10-40 nm thick) using 100-500 ALD cycles at 200, 225 and 250 °C, where the width of the wires (~400 µm) was defined by the used nozzle geometry (Fig. 1 shows the fabrication flow).Morphology studies of the Pt surface by scanning electron microscopy (Fig. 2) revealed that the film growth in the initial stages follows island-like nucleation, eventually becoming progressively denser with increasing number of ALD cycles. The Pt wire deposited using 200 cycles (nozzle passes) consist of interconnected network of Pt grains, while the one made using 400 cycles (~ 30 nm thick) consists of a continuous polycrystalline Pt film. This growth mechanism is typical for this thermal ALD (Pt+O3) process [4].Sensors were annealed at 600 °C in N2 to ensure temperature stability, and equipped with Au contact pads 2 mm apart (made by e-beam PVD through a shadow mask) for electrical characterization. The resistance was measured in the 25-400 °C range (selected characteristics shown in Fig. 3a), as well as in cryogenic temperatures down to 3 K (not shown here).Interestingly, higher temperature sensitivity S (Fig. 3b) was found for samples made by 200 ALD cycles, with a morphology of a network of interconnected Pt grains.The comparison of temperature coefficients of resistivity α (normalized sensitivity, Fig. 3c) clearly shown that the printed ALD Pt demonstrate better temperature sensing characteristics than the conventional 30 nm e-beam PVD Pt thin film, and is comparable also to the Pt100 standard.We will also discuss sensors printed on corrugated surfaces, i.e. black Si and Si gratings.The resistive Pt temperature sensors demonstrated in this study fabricated by a novel Atomic Layer 3D-printer are suitable for rapid printing in small-footprint areas where temperature sensing is required. Targeted, low temperature deposition with no need for lithographic masks or additional patterning paves the way for myriads of applications, e.g. on a chip, or in a battery. The characteristics of these sensors are shown to be comparable to a thin film sensor fabricated using conventional processing, as well as a Pt100 standard, thanks to high film quality delivered by the ALD process.We acknowledge the support of the H2020-EU ATOPLOT project (grant ID: 950785).

Searching for a route to synthesize in situ epitaxial Pr2Ir2O7 thin films with thermodynamic methods

In situ growth of pyrochlore iridate thin films has been a long-standing challenge due to the low reactivity of Ir at low temperatures and the vaporization of volatile gas species such as IrO3(g) and IrO2(g) at high temperatures and high PO2. To address this challenge, we combine thermodynamic analysis of the Pr-Ir-O2 system with experimental results from the conventional physical vapor deposition (PVD) technique of co-sputtering. Our results indicate that only high growth temperatures yield films with crystallinity sufficient for utilizing and tailoring the desired topological electronic properties and the in situ synthesis of Pr2Ir2O7 thin films is fettered by the inability to grow with PO2 on the order of 10 Torr at high temperatures, a limitation inherent to the PVD process. Thus, we suggest techniques capable of supplying high partial pressure of key species during deposition, in particular chemical vapor deposition (CVD), as a route to synthesis of Pr2Ir2O7.

Electrochemical Deposition of 3D Interconnects

3D integration is an emerging semiconductor technology that is used to form highly integrated small-factor electronic systems by vertically stacking two or more thin electronic chips in a single package. In metallization of 3D through-substrate vias (TSuV) such as through-silicon (TSV), through-glass (TGV), through-ceramic (TCV) interconnects et al, TSuV having a very small diameter (down to several microns) and long length (hundreds of microns) are filled with plated metal in order to create massive networks of uniform interconnects with high aspect ratio (length/diameter) > 20. Existing conventional industry processes are based on expensive physical-vapor-deposition (PVD) technology, which has serious limitations on via fill uniformity and metal quality (poor step coverage, voids and other defects) as well as is limited to aspect ratios < 10.Electrochemical deposition processes have been extensively studied for 3D interconnects. These processes are appealing due to superior performance as compared to conventional PVD processes at a substantially lower cost. NANO3D’s processes are based on novel electrochemical nanomaterials (plating solutions with self-assembled suppression-based organic additives to achieve bottom up fill and conformal electroless nickel alloys/copper barrier/seed) that provide defect-free TSuV fill with Cu or other metals for aspect ratios up to >20 [1-5]. Electrochemical deposition techniques have no limitations on chips design rules (down below 20 nm) and can be applied to all types of 3D applications from logic and memory to MEMS, wireless and power electronics. Electrochemical TSuV metallization is fully compatible with all process steps in various 3D TSuV manufacturing schemes currently under evaluation and can be easily incorporated into any finally standardized “process flow of reference”. The low cost electrochemical TSuV technology addresses the major threats for adoption of 3D TSuV that is the scalability to high aspect ratio and the cost. Another threat for adoption of 3D TSuV technology, that is related to power density limitation and thermal dissipation from thinned dies are expected to be solved by controlled expansion metal alloys (INVAR et al.) where electrochemical deposition offers high flexibility for designers with various aspect ratios and via sizes.In this work, copper and INVAR electroplating as well as nickel alloys and copper electroless deposition processes have been developed and characterized to achieve bottom up fill in trenches & vias of high aspect ratio and wide range of features sizes with superior interconnect properties including low electrical resistivity, CTE and internal stress. Plated films with low-thermal expansion (of about 0.4±0.1 (x10-6, (K-1)) and ultralow internal stress (of about 30 MPa) have been deposited on patterned substrates such as TSuV on various substrates, redistribution layers (RDL), pillars and bumps for 3D Interconnects. The plated patterned substrates are flat, smooth, uniform, defect free and possess with complete fill of TSuV and well controlled thickness non-uniformity of about 5 % @ 3 σ for Cu & INVAR & Ni alloys films (Figure). Thermal shock testing of plated TSuV substrates showed promising reliability & adhesion results after 500 cycles of thermal shock with no cracking and delamination. References V.M. Dubin, A.L. Gindilis, B.L. Walton, K. Norelli, A.U. Liyanage, S.R. Bauers and D.C. Johnson. ECS Transactions, 2017, 75 (34), 27.S. Taushanoff and V. M. Dubin. ECS Transactions, 2017, 77 (11), 877.V.M. Dubin, K. Norelli, and P.N. Plassmeyer. ECS Transactions, 2017, 77 (11), 887.V.M. Dubin, M.O. Lisunova, and B.L. Walton. Journal of The Electrochemical Society, 2017, 164, D321.S. Taushanoff, V.M. Dubin, A. Wallace and H. A. Mantooth. ECS Transactions, 2018, 85 (13) 803. Figure 1

STUDI IKATAN HIDROGEN PADA ORIENTASI MOLEKUL DISPERSE RED-1 DENGAN METODE PVD BERBANTUAN MEDAN LISTRIK

Organic molecules with a conjugated chain structure such as the Disperse Red-1 (DR-1) molecule are known as potential materials for photonic device applications. The aim of this research is to study the surface effect of Indium Tin Oxide (ITO) substrate and the external electric field of 2.6 MV / m in regulating the orientation of the DR-1 film molecules on the surface of the ITO substrate. The fabrication method used is the PVD (Physical Vapor Deposition) method assisted by an external electric field. This method is a modification of the conventional PVD method which is equipped with the addition of an external electric field (E) in the chamber. The film was made on the surface of the ITO substrate with the deposition of DR-1 molecules in a variation of the external electric field, namely zero field and E = 3.3 MV / m. The films were analyzed and characterized using XRD (X-Ray Diffraction) spectroscopy. The X-ray diffraction measurement analysis showed that the DR-1 molecules were arranged in an orderly manner parallel to the surface of the ITO substrate, indicating an indication of the strong surface effect of the ITO substrate from the hydrogen bonding of the DR-1 molecule with the ITO substrate. The results of spectroscopic measurements show that with an increase in the external electric field, there is an increase in the effect of aggregation of molecules arranged in an orderly manner perpendicular to the surface of the ITO substrate.

Electrodeposited Heusler alloy films with enhanced magneto-optical property

Growth of Heusler alloy films through techniques other than conventional physical vapor deposition presents a challenge for spintronic materials research. In this study an electrochemical deposition approach for these alloys is demonstrated in which sub-micron thickness control can be achieved. By using magneto optic Kerr effect and Kerr microscopy measurements a systematic study of surface magnetization reversal behavior of these films is presented. The results demonstrate that the growth of sub-micron films of Co2FeSn leads to significant enhancement in magneto optic Kerr rotation. A large Kerr rotation value up to 300 mdeg was observed for thin films of thickness ∼200 nm. The modified scheme reported here opens up a path for exploration of electrochemical method as a facile route for fabricating Heusler alloys with improved surface property.

Conformality of PVD shell layers on GLAD-nanorods investigated by Monte Carlo simulations

The quality of the shell coating around nanorods is critical in device applications. Conventional physical vapor deposition (PVD) techniques can be utilized for highly conformal shell coating formation in core-shell structure devices. To identify scalable fabrication techniques for conformal shell coatings, Monte Carlo (MC) simulations of PVD growth were performed under different atomic flux distributions and angles on arrays of glancing angle deposition (GLAD) nanorods, which were also generated by MC simulations. We investigated the conformality of PVD films (shell) around GLAD rod arrays (core) and analyzed the thickness uniformity of the shell layer across the sidewalls of rods. Our results show that Angular Flux-Normal Angle (A-NAD), which might correspond to high-pressure sputter deposition at normal incidence (HIPS at θ = 0o) can generate better conformal shell coating compared to others. In Uniform Flux-Normal Angle technique (U-NAD), which corresponds to a thermal evaporation deposition, the growth suffers from poor sidewall coverage. In addition, introducing a small angle to the flux also improves the shell conformality. Therefore, high-pressure sputter deposition technique is expected to provide superior conformality for a catalyst or semiconductor coating around base nanorods, for example for fuel cell and solar cell applications, with the help of obliquely incident atoms of the HIPS flux.

Scalable, Green Fabrication of Single-Crystal Noble Metal Films and Nanostructures for Low-Loss Nanotechnology Applications.

The confinement of spatially extended electromagnetic waves to nanometer-scale metal structures can be harnessed for application in information processing, energy harvesting, sensing, and catalysis. Metal nanostructures enable negative refractive index, subwavelength resolution imaging, and patterning through engineered metamaterials and promise technologies that will operate in the quantum plasmonics regime. However, the controlled fabrication of high-definition single-crystal subwavelength metal nanostructures has remained a significant hurdle due to the tendency for polycrystalline metal growth using conventional physical vapor deposition methods and the challenges associated with placing solution-grown nanocrystals in desired orientations and locations on a surface to manufacture functional devices. Here, we introduce a scalable and green wet chemical approach to monocrystalline noble metal thin films and nanostructures. The method enables the fabrication of ultrasmooth, epitaxial, single-crystal films of controllable thickness that are ideal for the subtractive manufacture of nanostructures through ion beam milling and additive crystalline nanostructure via lithographic patterning for large-area, single-crystal metasurfaces and high aspect ratio nanowires. Our single-crystal nanostructures demonstrate improved feature quality, pattern transfer yield, reduced optical and resistive losses, and tailored local fields to yield greater optical response and improved stability compared to those of polycrystalline structures-supporting greater local field enhancements and enabling practical advances at the nanoscale.

Synthesis and characterization of sol gel derived nontoxic CZTS thin films without sulfurization

AbstractRecently, great attention has been paid to the development of earth rich and nonhazardous Copper Zinc Tin Sulfide (CZTS–Cu2ZnSnS4) thin films for application in photovoltaic devices owing to its high absorption coefficient over the visible and infrared region. However, sulfurization process is an indispensable step in growing stoichiometric thin film using conventional physical vapor deposition. Hence, it is imperative to devise a liquid based technique without intentional sulfurization for the optimum quality growth of CZTS thin films. In the current work, layer‐by‐layer sol‐gel deposition technique was utilized to grow high quality CZTS thin films without sulfurization and their structural and optical characteristics were investigated using XRD studies and UV‐visible spectroscopy respectively. The morphology and chemical composition of the prepared CZTS films are estimated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis respectively. Highly absorbing and crystalline CZTS films have been successfully grown in the present work which could be further utilized as an absorber layer in photovoltaic applications.

On manufacturing multilayer-like nanostructures using misorientation gradients in PVD films

Due to their applicability for manufacturing dense, hard and stable coatings, Physical Vapor Deposition (PVD) techniques, such as High Power Impulse Magnetron Sputtering (HiPIMS), are currently used to deposit transition metal nitrides for tribological applications. Cr-Al-N is one of the most promising ceramic coating systems owing to its remarkable mechanical and tribological properties along with excellent corrosion resistance and high-temperature stability. This work explores the possibility of further improving Cr-Al-N coatings by modulation of its microstructure. Multilayer-like Cr1−xAlxN single films were manufactured using the angular oscillation of the substrate surface during HiPIMS. The sputtering process was accomplished using pulse frequencies ranging from 200 to 500 Hz and the resulting films were evaluated with respect to their hardness, Young’s modulus, residual stresses, deposition rate, crystallite size, crystallographic texture, coating morphology, chemical composition, and surface roughness. The multilayer-like structure, with periodicities ranging from 250 to 550 nm, were found associated with misorientation gradients and small-angle grain boundaries along the columnar grains, rather than mesoscopic chemical modulation of the microstructure. This minute modification of microstructure along with associated compressive residual stresses are concluded to explain the increased hardness ranging from 25 to 30 GPa, which is at least 20% over that expected for a film of the same chemical composition grown by a conventional PVD processing route.

Fabrication of Pb(Zr,Ti)O3 thin films utilizing unconventional powder magnetron sputtering (PMS)

Pb(Zr,Ti)O3 (PZT) ferroelectric ceramic films exhibit highly superior ferroelectric, pyroelectric and piezoelectric properties which are promising for a number of applications including non-volatile random access memory devices, non-linear optics, motion and thermal sensors, tunable microwave systems and in energy harvesting (EH) use. In this research, a thin layer of PZT was deposited on two different substrates of Strontium Titanate (STO) and Strontium ruthenate (SRO) by powder magnetron sputtering (PMS) system. The preliminary powders, consisting of PbO, ZrO2 and TiO2, were manually mixed and placed into the target holder of the PMS. The deposition was performed at an elevated temperature reaching up to 600 °C via a ceramic heater. This high temperature is required for PZT thin film crystallinity, which is never achieved in conventional physical vapour deposition processes. The phase structure, crystallite size, stress-strain and surface morphology of deposited thin films were characterized using X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The composition of the PZT thin films were also analysed by X-ray photoelectron spectroscopy (XPS). The mechanical properties of the thin films were evaluated with micro-scratch adhesive strength and micro hardness equipment. FESEM results showed that the PZT thin films were successfully deposited on both SRO and STO substrates. The surfaces of the coated samples were free from cracks, relatively smooth, uniform and dense. The profile of X-ray diffraction confirmed the formation of single-c-domain/single crystal perovskite phase grown on both substrates. The XPS analysis have shown that the PZT thin film grown by this method and that a target of PZT+10% PbO is a proper target for growing nominal PZT thin films. The adhesion strength and micro hardness results have confirmed the stability and durability of the thin film on the substrates, although higher values have been reported for thin film of PZT deposited on SRO surfaces.