Low-temperature conformal vacuum deposition of OLED devices using close-space sublimation

Close-space sublimation(CSS)has been demonstrated as an alternative vacuum deposition technique for fabricating organic light-emitting diodes(OLEDs).CSS utilizes a planar donor plate pre-coated with organic thin films as an area source to rapidly transfer the donor film to a device substrate at temperatures below 200℃.CSS is also conformal and capable of depositing on odd-shaped substrates using flexible donor media.The evaporation behaviors of organic donor films under CSS were fully characterized using model OLED materials and CSS-deposited films exhibited comparable device performances in an OLED stack to films deposited by conventional point sources.The low temperature and conformal nature of CSS,along with its high material utilization and short process time,make it a promising method for fabricating flexible OLED displays.

High Quality SiGe Layer Deposited by a New Ultrahigh Vacuum Chemical Vapor Deposition System

An ultrahigh vacuum chemical vapor deposition (UHV/CVD) system is developed and the details of its construction and operation are reported. Using high purity SiH4 and GeH4 reactant gases, the Si0.82Ge0.18 layer is deposited at 550℃. With the measurements by double crystal X-ray diffraction (DCXRD), transmission electron microscopy (TEM) and Rutherford backscattering spectroscppy (RBS) techniques, it is shown that the crystalline quality of the SiGe layer is good, and the underlying SiGe/Si heterointerface is sharply defined.

STUDY ON DIAMOND LIKE CARBON THIN FILM BY FILTERED VACUUM ARC DEPOSITION

Diamond like carbon thin film is successfully deposited on silicon, titanium and stainless steel substrate at low temperature in a filtered vacuum arc deposition system. Arc discharges are established on a graphite cathode in the system with a toroidal macroparticle filter. A cathode activating magnetic field and a filtered magnetic field to collimate the plasma beam are applied. Ion current convected by the plasma beam is measured with a negatively biased probe. It is shown that the magnetic field of the coils located on the plasma duct has a strong influence on cathode spot behavior. Orthogonally the designed experiments are carried out to optimize the deposition parameters of arc stability. Finally, the diamond like carbon thin films are studied by scanning electron microscope (SEM) and Raman spectrum.

Optical and electrical properties of BaSnO_(3) and In_2O_(3) mixed transparent conductive films deposited by filtered cathodic vacuum arc technique at room temperature

For the crystalline temperature of BaSnO_(3)(BTO)was above 650℃,the transparent conductive BTO-based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular beam epitaxy till now which limited there application in low temperature device process.In the article,the microstructure,optical and electrical of BTO and In_(2)O_(3) mixed transparent conductive BaInSnO_(x)(BITO)film deposited by filtered cathodic vacuum arc technique(FCVA)on glass substrate at room temperature were firstly reported.The BITO film with thickness of 300 nm had mainly In_(2)O_(3) polycrystalline phase,and minor polycrystalline BTO phase with(001),(011),(111),(002),(222)crystal faces which were first deposited at room temperature on amorphous glass.The transmittance was 70%–80%in the visible light region with linear refractive index of 1.94 and extinction coefficient of 0.004 at 550-nm wavelength.The basic optical properties included the real and imaginary parts,high frequency dielectric constants,the absorption coefficient,the Urbach energy,the indirect and direct band gaps,the oscillator and dispersion energies,the static refractive index and dielectric constant,the average oscillator wavelength,oscillator length strength,the linear and the third-order nonlinear optical susceptibilities,and the nonlinear refractive index were all calculated.The film was the n-type conductor with sheet resistance of 704.7Ω/□,resistivity of 0.02Ω⋅cm,mobility of 18.9 cm2/V⋅s,and carrier electron concentration of 1.6×10^(19) cm^(−3) at room temperature.The results suggested that the BITO film deposited by FCVA had potential application in transparent conductive films-based low temperature device process.

Structure of Cu-Phthalocyanine Vacuum Deposited on Inclined Glass Substrates

Cu-phthalocyanine is widely studied as a hole-transport layer in organic electronic devices. Since Cu-phthalocyanine is a molecular solid, the crystal structure depends on a circumstance to a great extent. Vacuum deposited layers were known to consist of two consecutive layers. In this article, Cu-phthalocyanine was deposited on the glass substrate inclined at several angles. The thickness of the first layer was found to be dependent on the substrate angle.

Experimental Research of DLC Film Deposited by Filtered Vacuum Arc Evaporation

Diamond like carbon (DLC) films was grown successfully on silicon, titanium and high speed steel (HSS) substrate at low temperature in a filtered vacuum arc deposition system. Arc discharges were established on a graphite cathode in this home built system with a toridal macroparticles filter. Ion current convected by the plasma beam was measured with a negatively biased probe. It was shown that the magnetic field of the coils located on the plasma duct has a strong influence on ion current. Scanning electron microscope (SEM), atomic force microscope (AFM) and Raman spectrum are used to study the DLC films. Tribological behaviors of the deposited film are also studied.

Effects of surface roughness of substrate on properties of Ti/TiN/Zr/ZrN multilayer coatings

Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-sectional morphology of the obtained multilayer coatings were investigated. The results show that the Vickers hardness of Ti/TiN/Zr/ZrN multilayer coating, with a film thickness of 11.37 μm, is 29.36 GPa. The erosion and salt spray resistance performance of Cr_17Ni_2 steel substrates can be evidently improved by Ti/TiN/Zr/ZrN multilayer coating. The surface roughness of Cr_17Ni_2 steel substrates plays an important role in determining the mechanical and erosion performances of Ti/TiN/Zr/ZrN multilayer coatings. Overall, a low value of the surface roughness of substrates corresponds to an improved performance of erosion and salt spray resistance of multilayer coatings. The optimized performance of Ti/TiN/Zr/ZrN multilayer coatings can be achieved provided that the surface roughness of Cr_17Ni_2 steel substrates is lower than 0.4μm.

Growth of Ge Layer on Relaxed Ge-Rich SiGe by Ultrahigh Vacuum Chemical Vapor Deposition

The paper describes the growth of a germanium （Ge） film on a thin relaxed Ge-rich SiGe buffer. The thin Ge-rich SiGe buffer layer was achieved through a combination of ultrahigh vacuum chemical vapor deposition （UHVCVD） SiGe epitaxial growth and SiGe oxidation. A lower Ge content strained SiGe layer was first grown on the Si （001） substrate and then the Ge mole fraction was increased by oxidation. After removal of the surface oxide, a higher Ge content SiGe layer was grown and oxidized again. The Ge mole fraction was increased to 0.8 in the 50 nm thick SiGe layer. Finally a 150 nm thick pure Ge film was grown on the SiGe buffer layer using the UHVCVD system. This technique produces a much thinner buffer than the conventional compositionally graded relaxed SiGe method with the same order of magnitude threading dislocation density.

Comparison of Vacuum Metal Deposition and 1,2-lndandione/Ninhydrin Reagent Method for the Development of Fingerprints on Renminbi

It is extremely difficult to develop fingerprints from the surface of currency.There are studies reporting that the high vacuum metal deposition(VMD)method can be used to detect fingerprints on certain types of currency notes.Both VMD and 1,2-indandione/ninhydrin techniques are employed to visualize latent fingermarks on porous surfaces,such as paper.The current study explores whether the VMD method or 1,2-indandione/ninhydrin reagent method is more effective in the development of fingerprints on remninbi(RMB).Uncirculated,circulated,and water-exposed RMB was utilized in this study,along with five donors who ranged in their age and potential to leave fingermarks.Samples were aged for a determined period(for uncirculated and circulated RMB,times were 1,3,5,10,and 35 days;for watei^exposed RMB,exposure time was 1 day)and then treated with VMD and 1,2-indandione/ninhydrin.The results suggested that the 1,2-indandione/ninhydrin reagent yielded a better effect for both circulated and uncirculated RMB.For the RMB exposed to water,VMD performed better and gave limited results in terms of fingerprint development,which could serve as a reference for actual forensic cases.

Key parameters of two typical intercalation reactions to prepare hybrid inorganic-organic perovskite films

A star hybrid inorganic-organic perovskite material selected as an outstanding absorbing layer in solar cells benefits from multiple preparation techniques and excellent photoelectric characteristics. Among numerous synthetic processes, uniform, compact, and multi-stack perovskite thin films can be manufactured using vacuum deposition. During sequential vacuum deposition, the penetration ability of the organic molecules cannot be effectively controlled. In addition, the rela- tionship between the thickness of the inorganic seeding layer and the organic molecule concentration for optimized devices using an evaporation-solution method is unclear. In this work, we prepared high-quality perovskite films by effectively con- trolling the penetration ability and chemical quantity of organic methyl ammonium iodide by monitoring the evaporation pressure and time. Thus, a device efficiency of over 15% was achieved with an all-vacuum prepared perovskite film. For the evaporation-solution method, we reacted different thicknesses of inorganic lead iodine with various concentrations of the organic molecule solution. The inorganic layer thickness and organic molecule concentration showed a linear relationship to achieve an optimum perovskite film, and an empirical formula was obtained. This work noted the key parameters of two intercalation reactions to prepare perovskite films, which paves a way to deliver a device that enables multi-layered structures, such as tandem solar cells.

Effects of Carbon Fiber Gas Pressure,Temperature and Deposition Distance on Thermo Fluids Phenomena in Vacuum Deposition Machine

A numerical analysis method （DSMC, Direct Simulation Monte Carlo）[1] was developed to simulate the molecular motion of rarefied gases. In the present paper, numerical approaches by the DSMC method have been carded out. By the computation model of CC-40F carbon coater, the cylindrical deposition machine has axial symmetry; the flows inside the vacuum chamber were analyzed. The substrates were put on the bottom and the fiber near the ceiling in the computational domain. In the computational model, air and carbon molecules are working ones. The effects of the air gas pressure variation in the chamber, the effects of the deposition distance variation and the surface temperature variation of the carbon fiber on thermo fluids phenomena are discussed and visualized. Changing the number density of carbon and air, the temperature of the carbon and the velocity of the carbon in the chamber are discussed. With changing the surface temperature of the carbon fiber, qualitative assay of experiment and simulation result is in similar trend very well. The DSMC method is a forceful tool for the study of rarefied gas flow in vacuum deposition machine.

STUDY ON COMPOSITION, MICROSTRUCTURE AND HARDNESS OF DLC FILMS BY VCAD

DLC super-hard films have been deposited on the substrates of single crystalline Si, pure Ti and stainless steel 18-8 by a method of vacuum cathode arc deposition (VCAD). The composition, microstructure and micro-hardness of the films have been studied in this paper. The results indicate that hardness of the DLC films is different on the different substrates. Hardness of the films increases with decreasing in surface roughness of the films. The maximum value of micro-hardness belongs to the DLC films deposited under the hydrogen pressure of 0.35Pa and the negative bias of 100V.

Tribological properties of multilayer tetrahedral amorphous carbon coatings deposited by filtered cathodic vacuum arc deposition

Tetrahedral amorphous carbon(ta‐C)has emerged as an excellent coating material for improving the reliability of application components under high normal loads.Herein,we present the results of our investigations regarding the mechanical and tribological properties of a 2‐μm‐thick multilayer ta‐C coating on high‐speed steel substrates.Multilayers composed of alternating soft and hard layers are fabricated using filtered a cathodic vacuum arc with alternating substrate bias voltages(0 and 100 V or 0 and 150 V).The thickness ratio is discovered to be 1:3 for the sp2‐rich and sp3‐rich layers.The results show that the hardness and elastic modulus of the multilayer ta‐C coatings increase with the sp3 content of the hard layer.The hardness reached approximately 37 GPa,whereas an improved toughness and a higher adhesion strength(>29 N)are obtained.The friction performance(μ=0.07)of the multilayer coating is similar to that of the single layer ta‐C thick coating,but the wear rate(0.13×10^(–6) mm^(3)/(N∙m))improved under a high load of 30 N.We further demonstrate the importance of the multilayer structure in suppressing crack propagation and increasing the resistance to plastic deformation(H3/E2)ratio.

1.3μm high-power superluminescent diode

The result of the evaporation of Sio/SiO2 two layer antireflection coatings monitored by the MODEL IL 400 DEPOSITION CONTROLLER is reported.A superluminescent diode with high output power is fabricated by evaporating antireflection coating on the front facet of 1.3μm buried heterostructure laser.

Study on optical compound films

Using the compound materials and double e-gun evaporation,the compound optical films have been successfully deposited on K9 glass substrate.The refractive index of optical compund films deposited in diffeent parameters have been measured and theoretical formula for calculation refractive index of compound films have been derived.It is shown that the experimental curve for the variation of refractive index with wavelength in 0.4￣1.4 μm region and the theoretical one agree very well.Using these films,the laser reflecting mirror has been successfully coated.

Morphology and Field Emission of ZnO Nanomaterials at Different Positions

By simply adjusting the temperature and the number of materials, rod-like ZnO with different morphology, such as ZnO nanoneedles, were synthesized by a flexible thermal evaporation method. The ZnO nanorod array has the lowest turn-on field, the highest current density, and the highest emission efficiency due to its good contact with the substrate and relatively weak field shielding effect. Experiments show that the morphology and orientation of one-dimensional ZnO nanomaterials have a great influence on its conduction field and emission current density, and the nanoarrays also contribute to electron emission. The research results have a certain reference value for the application of ZnO nanorod arrays as cathode materials for field emission devices.

Analysis,fabrication,and measurement of Y aperture element frequency selective surface

The analysis of Y aperture element frequency selective surface （FSS） using the spectral domain method and the moment method is presented. With the vacuum depositing and photolithography, the corresponding Y aperture element FSS was produced, and it was tested in the microwave darkroom. The calculated and measured results are in good agreement.

Structure optimization of organic light-emitting devices

A triple layer organic light-emitting diode (OLED) with two heterostructure of indium-tin oxide (ITO)/N,N’-diphenyl-N, N’-bis(1-naphthyl) (1,1’-biphenyl)-4,4’-diamine (NPB)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/ 8-Hydrox- yquinoline aluminum (Alq3)/Mg:Ag has been fabricated by using the vacuum deposition method. The influence of different film thickness of BCP layer on the performance of the OLEDs has been investigated. The results show that when the thickness of the BCP layer film gradually r...

Optoelectronic properties and Seebeck coefficient in SnSe thin films

SnSe thin films of thickness 180 nm have been deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 523 ± 5 K and pressure of 10^（-5） mbar.The as-prepared SnSe thin films are characterized for their structural,optical and electrical properties by various experimental techniques.The p-type conductivity,near-optimum direct band gap,high absorption coefficient and good photosensitivity of the SnSe thin film indicate its suitability for photovoltaic applications.The optical constants,loss factor,quality factor and optical conductivity of the films are evaluated.The results of Hall and thermoelectric power measurements are correlated to determine the density of states,Fermi energy and effective mass of carriers and are obtained as 2.8×10^（17）cm^（-3）,0.03 eV and 0.05m_0 respectively.The high Seebeck coefficient ≈ 7863 μV/K,reasonably good power factor ≈7.2×10^（-4） W/（m·K^2） and thermoelectric figure of merit ≈1.2 observed at 42 K suggests that,on further work,the prepared SnSe thin films can also be considered as a possible candidate for cryogenic thermoelectric applications.