This research was supported by Unmanned Vehicles Advanced Core Technology Research and Development Program through the Unmanned Vehicle Advanced Research Center (UVARC) funded by the Ministry of Science, ICT and Future Planning, the Republic of Korea (2016M1B3A1A01937575)

Caution: Some chemicals (i.e., buffered oxide etchant, isopropyl alcohol, etc.) used in this protocol can be hazardous to health. Please consult all relevant material safety data sheets before any sample preparation takes place. Utilize appropriate personal protective equipment (e.g., lab coats, safety glasses, gloves, etc.) and engineering controls (e.g., wet station, fume hood, etc.) when handling etchants and solvents.
1. Preparation of the Si Substrate
<ol>
	<li>Using a diamond cutter, cut a 4 inch silicon (Si) wafer into 2 cm x 2 cm sized squares. To make colored samples, the substrate is typically cut 2 cm x 2 cm, but can be larger, depending on the size of the sample holder used for oblique angle deposition.</li>
	<li>To remove native oxide using Polytetrafluoroethylene (PTFE) dipper, dip the cleaved Si substrates in buffered oxide etchant (BOE) for 3 s. Caution: Please wear appropriate protection for safety.</li>
	<li>Clean the cleaved Si substrates sequentially in acetone, isopropyl alcohol (IPA), and deionized (DI) water for 3 s each.
	<ol>
		<li>Using PTFE cleaning jig, sonicate the cleaved Si substrates with acetone in an ultrasonic bath for 3 min at a frequency of 35 kHz.</li>
		<li>To remove the acetone, rinse the cleaved Si substrates with IPA.</li>
		<li>As the last step of cleaning, rinse the cleaved Si substrates with DI water.</li>
	</ol>
	</li>
	<li>To remove moisture, dry the clean substrate with a nitrogen blow gun while holding it with forceps.&#160;</li>
</ol>
2. Deposition of the Au Reflector
<ol>
	<li>Using forceps and carbon tape, fix the cleaned Si substrates onto a flat sample holder and place the holder into the chamber of the electron beam evaporator with Ti and Au sources.</li>
	<li>Evacuate the chamber for 1 h to reach high vacuum. The base pressure of the vacuum chamber should be 4 x 10-6 Torr.</li>
	<li>Deposit the Ti layer as an adhesion layer to a thickness of 10 nm with 5 - 7% of electron beam power controlled in manual mode at a DC voltage of 7.5 kV, which gives a deposition rate of 1 &#197;/sec. 
	Note: A Cr layer of the same thickness, instead of a Ti layer, can be deposited as the adhesion layer.</li>
	<li>Deposit the Au layer as a reflection layer to a thickness of 100 nm with 13-15% of electron beam power controlled in manual mode at a DC voltage of 7.5 kV, which gives a deposition rate of 2 &#197;/sec. 
	Note: The thickness of the Au reflection layer can be greater than 100 nm. A thickness of 100 nm is deposited here to make the reflection layer as thin as possible while maintaining the optical properties of the Au.</li>
	<li>After the Au layer deposition, vent the chamber and take out the samples. They will need to be reloaded with the inclined sample holder for the oblique angle deposition.</li>
</ol>
3. Preparation of the Inclined Sample Holder for Oblique Angle Deposition
Note: There are several methods that can be used for oblique deposition, such as the z-axis rotating chuck16, but this requires equipment modification and films can only be deposited at one angle at a time. To efficiently observe the changes in color produced by different deposition angles, we used sample holders that inclined the samples at different angles. For precision, the inclined sample holder can be made using metal processing equipment. However, in this paper, we introduce a simple method that can be easily followed.
<ol>
	<li>Prepare a metal plate made of an easily bendable metal such as aluminum.</li>
	<li>Cut the metal plate into three 2 cm x 5 cm pieces.</li>
	<li>Fix the metal piece to the floor alongside a protractor, hold the short side and bend the metal to the desired deposition angle (i.e., 30&#176;, 45&#176;, and 70&#176;).</li>
	<li>Attach the bent metal pieces to the 4 inch sample holder using carbon tape.</li>
</ol>
4. Oblique Angle Deposition of Ge Layer
Note: In this section, refer to the schematic diagrams in Figure 1 of the samples deposited on the inclined sample holders, and porous Ge films, following oblique angle deposition.
<ol>
	<li>Fix the four Au deposited samples with carbon tape to an inclined sample holder at angles of 0&#176;, 30&#176;, 45&#176;, and 70&#176;, respectively.</li>
	<li>Load the Au-deposited samples on the inclined sample holder into the electron beam evaporator with a Ge source for oblique angle deposition.</li>
	<li>Evacuate the chamber for 1 h to reach high vacuum. The base pressure of the vacuum chamber should be 4 x 10-6 Torr.</li>
	<li>Deposit the Ge layer as a coloring layer with 6 - 8% of electron beam power controlled in manual mode at a DC voltage of 7.5 kV, which gives a deposition rate of 1 &#197;/sec. The deposition thicknesses of the Ge layer on the four samples are 10 nm, 15 nm, 20 nm, and 25 nm, respectively. 
	Note: The deposition thicknesses of 10 nm, 15 nm, 20 nm, and 25 nm were selected to facilitate comparison of the color changes for each deposition angle. A different angle and thickness (5 - 60 nm) can be chosen to achieve a particular color.</li>
	<li>After the Ge layer deposition, vent the chamber and take out the samples.</li>
</ol>
5. Oblique Angle Deposition Process for Large Areas
Note: If the size of the sample used for oblique angle deposition is small, it can be fabricated by the process detailed in step 4. However, if the size of the sample to be fabricated is large, it becomes difficult to maintain film uniformity due to variation in the evaporation flux along the z-axis16. Therefore, a separate additional process, step 5, is required to fabricate larger samples and achieve a uniform color.
<ol>
	<li>For a 2 inch wafer, after depositing the Au layer on the large sample in step 2, fix the Au-deposited large sample to the 45&#176; inclined sample holder. 
	Note: Since our inclined sample holder is designed to fit small samples, loading large samples at all the angles (i.e., 0&#176;, 30&#176;, 45&#176;, and 70&#176;) will create interference between samples. Therefore, to obliquely deposit large-sized samples at various angles in one process, it is necessary to have an inclined sample holder suitable for large-sized samples.</li>
	<li>Load the Au-deposited large sample on the inclined sample holder into the electron beam evaporator with a Ge source for oblique angle deposition. 
	Note: When loading the sample, the second deposition layer must be deposited in the same direction as the first deposition, so note the direction of the loaded sample. For convenience, it is recommended that the sample holder is loaded facing the front of the chamber.</li>
	<li>Evacuate the chamber for 1 h to reach high vacuum. The base pressure of the vacuum chamber should be 4 x 10-6 Torr.</li>
	<li>Deposit the Ge layer as a coloring layer to a deposition thickness of 10 nm, which is half of the target thickness of 20 nm, with 6 - 8% of electron beam power controlled in manual mode at a DC voltage of 7.5 kV, which gives a deposition rate of 1 &#197;/sec.</li>
	<li>After the deposition of the first Ge layer is finished, vent the chamber and take out the sample, because the sample needs to be repositioned and reloaded.</li>
	<li>Fix the sample to the inclined sample holder in a position which is upside down with respect to the position of the first deposition.</li>
	<li>Load the sample on the inclined sample holder with the Ge source so that the holder faces in the same direction as the first deposition.</li>
	<li>Evacuate the chamber for 1 h to reach high vacuum. The base pressure of the vacuum chamber should be 4 x 10-6 Torr.</li>
	<li>Deposit the Ge layer as a coloring layer to a deposition thickness of 10 nm, which is half of the target thickness of 20 nm, with 6 - 8% of electron beam power controlled in manual mode at a DC voltage of 7.5 kV, which gives a deposition rate of 1 &#197;/sec.</li>
	<li>After the Ge layer deposition, vent the chamber and take out the sample.</li>
</ol>

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The authors have nothing to disclose.

In conventional thin film coatings for coloration3,4,5,6, the color can be controlled by altering different materials and adjusting the thickness. The choice of materials with different refractive indices is limited for tuning various colors. To relax this limitation, we exploited the oblique angle deposition to thin-film color coating. Depending on the deposition angle, the porosity of the Ge ...

In general, the performance of thin-film optical coatings is based on the type of optical interference they produce, such as high reflection or transmission. In dielectric thin-films, optical interference can be obtained simply by satisfying conditions such as quarter wave thickness (&#955;/4n). Interference principles have long been used in various optical applications such as Fabry-Perot interferometers and distributed Bragg reflectors1,2. In recent years, thin film structures using highly absorbent materials such as metals and semiconductors have been widely studied3,4,5,6. Strong optical interference can be obtained by thin-film coating an absorbent semiconductor material on a metal film, which produces non-trivial phase changes in the reflected waves. This type of structure allows ultra-thin coatings which are considerably thinner than dielectric thin-film coatings.
Recently, we studied ways of improving the color tunability and color purity of highly absorbent thin-films using porosity7. By controlling the porosity of the deposited film, the effective refractive index of the thin-film medium can be changed8. This change in the effective refractive index allows the optical characteristics to be improved. Based on this effect, we designed ultra-thin color films with different thicknesses and porosities by calculations using rigorous coupled wave analysis (RCWA)9. Our design presents colors with different film thicknesses at each porosity7.
We employed a simple method, oblique angle deposition, to control the porosity of highly absorbent thin-film coatings. The oblique angle deposition technique basically combines a typical deposition system, such as an electron beam evaporator or thermal evaporator, with a tilted substrate10. The oblique angle of incident flux creates atomic shadowing, which produces areas that the vapor flux cannot reach directly11. The oblique angle deposition technique has been widely used in various thin-film coating applications12,13,14.
In this work, we detail the processes for fabricating ultra-thin color films by oblique deposition using an electron beam evaporator. Also, additional methods for large-area processing are presented separately. In addition to the process steps, some notes that should be taken into consideration during the fabrication process are explained in detail.
We also review processes for measuring the reflectance of the fabricated samples and converting them into color information for analysis, so that they can be expressed in CIE color coordinates and RGB values15. Furthermore, some issues to consider in the fabrication process of ultra-thin color films are discussed.

<table><tbody><tr><td>&amp;nbsp;KVE-2004L</td><td>Korea Vacuum Tech. Ltd.</td><td></td><td>E-beam evaporator system</td></tr><tr><td>Cary 500</td><td>Varian, USA</td><td></td><td>UV-Vis-NIR spectrophotometer</td></tr><tr><td>T1-H-10</td><td>Elma</td><td></td><td>Ultrasonic bath</td></tr><tr><td>HSD150-03P</td><td>Misung Scientific Co., Ltd</td><td></td><td>Hot plate</td></tr><tr><td>Isopropyl Alcohol (IPA)</td><td>OCI Company Ltd.</td><td></td><td>Isopropyl Alcohol (IPA)</td></tr><tr><td>Buffered Oxide Etch 6:1</td><td>Avantor</td><td></td><td>Buffered Oxide Etch 6:1</td></tr><tr><td>Acetone</td><td>OCI Company Ltd.</td><td></td><td>Acetone</td></tr><tr><td>4 inch Silicon Wafer</td><td>Hi-Solar Co., Ltd.</td><td></td><td>4 inch Silicon Wafer (P-100, 1 - 20 ohm.cm, Single side polished, Thickness: 440 &amp;plusmn; 20 &amp;mu;m)</td></tr><tr><td>2 inch Silicon Wafer</td><td>Hi-Solar Co., Ltd.</td><td></td><td>2 inch Silicon Wafer (P-100, 1 - 20 ohm.cm, Single side polished, Thickness: 440 &amp;plusmn; 20 &amp;mu;m)</td></tr></tbody></table>

fabrication of ultra-thin color films with highly absorbing media using oblique angle deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

Figure 2a shows images of the 2 cm x 2 cm fabricated samples. The samples were fabricated so that the films had different thicknesses (i.e., 10 nm, 15 nm, 20 nm, and 25 nm) and were deposited at different angles (i.e., 0&#176;, 30&#176;, 45&#176;, and 70&#176;). The color of the deposited films changes depending on the combination of both the thickness of the samples and the deposition angle. The changes in color result from changes in the porosity of the film. Depending on...

Watch this Scientific Journal Video about Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition at JoVE.com

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

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Engineering

8.2K Views.  Gwangju Institute of Science and Technology. Presenteren we een gedetailleerde methode voor het fabriceren van ultradunne kleur films met verbeterde eigenschappen voor optische coatings. De schuine hoek afzetting techniek met behulp van een electron beam verdamper kan verbeterde kleur tunability en zuiverheid. Bewerkte films van Ge en Au op Si substraten werden geanalyseerd door metingen van de reflectiecoëfficiënt en informatie kleurconversie.

Video: Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

Fabrication of Spatially Confined Complex Oxides

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from the inherent strong electron correlations that reside within them. These materials can also possess electronic phase separation in which regions of vastly different resistive and magnetic behavior can coexist within a single crystal alloy material. By reducing the scale of these materials to length scales at and below the inherent size of the electronic domains, novel behaviors can be exposed. Because of this and the fact that spin-charge-lattice-orbital order parameters each involve correlation lengths, spatially reducing these materials for transport measurements is a critical step in understanding the fundamental physics that drives complex behaviors. These materials also offer great potential to become the next generation of electronic devices 1-3. Thus, the fabrication of low dimensional nano- or micro-structures is extremely important to achieve new functionality. This involves multiple controllable processes from high quality thin film growth to accurate electronic property characterization. Here, we present fabrication protocols of high quality microstructures for complex oxide manganite devices. Detailed descriptions and required equipment of thin film growth, photo-lithography, and wire-bonding are presented.

We describe the use of pulsed laser deposition (PLD), photolithography and wire-bonding techniques to create micrometer scale complex oxides devices. The PLD is utilized to grow epitaxial thin films. Photolithography and wire-bonding techniques are introduced to create practical devices for measurement purposes.

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from ...

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

Chemistry

Formation of Thick Dense Yttrium Iron Garnet Films Using Aerosol Deposition

Aerosol deposition (AD) is a thick-film deposition process that can produce layers up to several hundred micrometers thick with densities greater than 95% of the bulk. The primary advantage of AD is that the deposition takes place entirely at ambient temperature; thereby enabling film growth in material systems with disparate melting temperatures. This report describes in detail the processing steps for preparing the powder and for performing AD using the custom-built system. Representative characterization results are presented from scanning electron microscopy, profilometry, and ferromagnetic resonance for films grown in this system. As a representative overview of the capabilities of the system, focus is given to a sample produced following the described protocol and system setup. Results indicate that this system can successfully deposit 11 &#181;m thick yttrium iron garnet films that are &#160;&#62; 90% of the bulk density during a single 5 min deposition run. A discussion of methods to afford better control of the aerosol and particle selection for improved thickness and roughness variations in the film is provided.

This report describes the use of a custom-built system to perform aerosol deposition of thick films of yttrium iron garnet onto sapphire substrates at RT. The deposited films are characterized using scanning electron microscopy, profilometry, and ferromagnetic resonance to give a representative overview of the capabilities of the technique.

Aerosol deposition (AD) is a thick-film deposition process that can produce layers up to several hundred micrometers thick with densities greater than 95% ...

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two chalcogenide compositions are demonstrated: Ge23Sb7S70 and As40S60, which have both been studied extensively for planar mid-infrared (mid-IR) microphotonic devices. In this approach, uniform thickness films are fabricated through the use of computer numerical controlled (CNC) motion. Chalcogenide glass (ChG) is written over the substrate by a single nozzle along a serpentine path. Films were subjected to a series of heat treatments between 100 &#176;C and 200 &#176;C under vacuum to drive off residual solvent and densify the films. Based on transmission Fourier transform infrared (FTIR) spectroscopy and surface roughness measurements, both compositions were found to be suitable for the fabrication of planar devices operating in the mid-IR region. Residual solvent removal was found to be much quicker for the As40S60 film as compared to Ge23Sb7S70. Based on the advantages of electrospray, direct printing of a gradient refractive index (GRIN) mid-IR transparent coating is envisioned, given the difference in refractive index of the two compositions in this study.

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

A method of uniform thickness solution-derived chalcogenide glass film deposition is demonstrated using computer numerical controlled motion of a single-nozzle electrospray.

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two ...

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m-2, and a maximum current efficiency of 1.15 cd A-1. The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

A protocol is presented for fabricating high-performance, pure blue ZnCdS/ZnS-based quantum dots light-emitting diodes by employing an autoxidized aluminum cathode.

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation ...

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (Cu variant) entropy-stabilized oxides. Phase pure and chemically homogeneous (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (x = 0.20, 0.27, 0.33) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (x = 0.11, 0.27) ceramic pellets are synthesized and used in the deposition of ultra-high quality, phase pure, single crystalline thin films of the target stoichiometry. A detailed methodology for the deposition of smooth, chemically homogeneous, entropy-stabilized oxide thin films by pulsed laser deposition on (001)-oriented MgO substrates is described. The phase and crystallinity of bulk and thin film materials are confirmed using X-ray diffraction. Composition and chemical homogeneity are confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface topography of thin films is measured with scanning probe microscopy. The synthesis of high quality, single crystalline, entropy-stabilized oxide thin films enables the study of interface, size, strain, and disorder effects on the properties in this new class of highly disordered oxide materials.

The synthesis of high quality bulk and thin film (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O entropy-stabilized oxides is presented.

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and ...

Procedure for the Transfer of Polymer Films Onto Porous Substrates with Minimized Defects

The fabrication of devices containing thin film composite membranes necessitates the transfer of these films onto the surfaces of arbitrary support substrates. Accomplishing this transfer in a highly controlled, mechanized, and reproducible manner can eliminate the creation of macroscale defect structures (e.g., tears, cracks, and wrinkles) within the thin film that compromise device performance and the usable area per sample. Here, we describe a general protocol for the highly controlled and mechanized transfer of a polymeric thin film onto an arbitrary porous support substrate for eventual use as a water filtration membrane device. Specifically, we fabricate a block copolymer (BCP) thin film on top of a sacrificial, water-soluble poly(acrylic acid) (PAA) layer and silicon wafer substrate. We then utilize a custom-designed, 3D-printed transfer tool and drain chamber system to deposit, lift-off, and transfer the BCP thin film onto the center of a porous anodized aluminum oxide (AAO) support disc. The transferred BCP thin film is shown to be consistently placed onto the center of the support surface due to the guidance of the meniscus formed between the water and the 3D-printed plastic drain chamber. We also compare our mechanized transfer-processed thin films to those that have been transferred by hand with the use of tweezers. Optical inspection and image analysis of the transferred thin films from the mechanized process confirm that little-to-no macroscale inhomogeneities or plastic deformations are produced, as compared to the multitude of tears and wrinkles produced from manual transfer by hand. Our results suggest that the proposed strategy for thin film transfer can reduce defects when compared to other methods across many systems and applications.

We present a procedure for highly controlled and wrinkle-free transfer of block copolymer thin films onto porous support substrates using a 3D-printed drain chamber. The drain chamber design is of general relevance to all procedures involving transfer of macromolecular films onto porous substrates, which is normally done by hand in an irreproducible fashion.

The fabrication of devices containing thin film composite membranes necessitates the transfer of these films onto the surfaces of arbitrary support ...

Development of Efficient OLEDs from Solution Deposition

The use of highly efficient organic emitters based on the thermally activated delayed fluorescence (TADF) concept is interesting due to their 100% internal quantum efficiency. Presented here is a solution deposition method for the fabrication of efficient organic light-emitting diodes (OLEDs) based on a TADF emitter in a simple device structure. This fast, low-cost, and efficient process can be used for all OLED emissive layers that follow the host-guest concept. The fundamental steps are described along with necessary information for further reproduction. The goal to establish a general protocol that can be easily adapted for principal organic emitters currently under study and development.

Presented here is a protocol for the fabrication of efficient, simple, solution-deposited organic light-emitting diodes with low roll-off.

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

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