scholarly journals Evaporation of Adherent Al-Films on Single Crystalline LiNbO3Substrates

1992 ◽  
Vol 14 (4) ◽  
pp. 245-249
Author(s):  
E. Schippel
Keyword(s):  
High Vacuum ◽  
Substrate Material ◽  
Large Area ◽  
Single Crystalline ◽  
Film Adhesion ◽  
Crystalline Substrate ◽  
Substrate Wafer ◽  
Mixed Film ◽  
Acoustic Wave Devices ◽  
Polished Substrate

LiNbO3is used as a single crystalline substrate material for the manufacturing of surface acoustic wave devices as frequency selective components. On the polished substrate wafer, Al with a film thickness of about 400 nm is evaporated in a high vacuum.The difficulties of the inadequate adhesion of the structured Al-film were eliminated by systematical investigations. Films that were adherent to the total surface could be prepared by evaporating an intermediate film of Cr or SiOxor, otherwise, a mixed film of Al with Si.An ultrasonic test for adhesion strength was developed that results in an assessment of local and also large-area film adhesion.

Low-energy point-reflection EM

1995 ◽  
Vol 53 ◽  
pp. 610-611
Author(s):  
J. C. H. Spence ◽  
X. Zhang ◽  
J. M. Zuo ◽  
U. Weierstall ◽  
E. Munro ◽  
...  
Keyword(s):  
Low Voltage ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Experimental Point ◽  
Crystalline Substrate ◽  
Point Reflection ◽  
Reflection Geometry ◽  
Optical Analog ◽  
Point Projection ◽  
Atomically Flat

The limited penetration of the low-voltage point-projection microscope (PPM) may be avoided by using the reflection geometry to image clean surfaces in ultra-high vacuum. Figure 1 shows the geometry we are using for experimental point-reflection (PRM) imaging. A nanotip field-emitter at about 100 - 1000 volts is placed above a grounded atomically flat crystalline substrate, which acts as a mirror and anode. Since most of the potential is dropped very close to the tip, trajectories are reasonably straight if the sample is in the far-field of the tip. A resolution of 10 nm is sought initially. The specular divergent RHEED beam then defines a virtual source S' below the surface, resulting in an equivalent arrangement to PPM (or defocused CBED). Shadow images of surface asperities are then expected on the distant detector, out of focus by the tip-to-sample distance. These images can be interpreted as in-line electron holograms and so reconstructed (see X. Zhang et al, these proceedings). Optical analog experiments confirm the absence of foreshortening when the detector is parallel to the surface.

scholarly journals The Growth of Semiconductor Thin Films Studied by RHEED

1990 ◽  
Vol 43 (5) ◽  
pp. 583
Author(s):  
GL Price
Keyword(s):  
Thin Films ◽  
Surface Science ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Large Area ◽  
Growth Modes ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Recent Developments

Recent developments in the growth of semiconductor thin films are reviewed. The emphasis is on growth by molecular beam epitaxy (MBE). Results obtained by reflection high energy electron diffraction (RHEED) are employed to describe the different kinds of growth processes and the types of materials which can be constructed. MBE is routinely capable of heterostructure growth to atomic precision with a wide range of materials including III-V, IV, II-VI semiconductors, metals, ceramics such as high Tc materials and organics. As the growth proceeds in ultra high vacuum, MBE can take advantage of surface science techniques such as Auger, RHEED and SIMS. RHEED is the essential in-situ probe since the final crystal quality is strongly dependent on the surface reconstruction during growth. RHEED can also be used to calibrate the growth rate, monitor growth kinetics, and distinguish between various growth modes. A major new area is lattice mismatched growth where attempts are being made to construct heterostructures between materials of different lattice constants such as GaAs on Si. Also described are the new techniques of migration enhanced epitaxy and tilted superlattice growth. Finally some comments are given On the means of preparing large area, thin samples for analysis by other techniques from MBE grown films using capping, etching and liftoff.

Large Area Surface Treatment by Ion Beam Technology

1996 ◽  
Vol 438 ◽  
Author(s):  
R. L. C. Wu ◽  
W. Lanter
Keyword(s):  
Ion Beam ◽  
High Vacuum ◽  
Polycrystalline Diamond ◽  
Carbon Films ◽  
Ultra High Vacuum ◽  
Diamond Like Carbon ◽  
Chemical Compositions ◽  
Rf Power ◽  
Large Area ◽  
Ion Energy

AbstractAn ultra high vacuum ion beam system, consisting of a 20 cm diameter Rf excilted (13.56 MHz) ion gun and a four-axis substrate scanner, has been used to modify large surfaces (up to 1000 cm2) of various materials, including; infrared windows, silicon nitride, polycrystalline diamond, 304 and 316 stainless steels, 440C and M50 steels, aluminum alloys, and polycarbonates; by depositing different chemical compositions of diamond-like carbon films. The influences of ion energy, Rf power, gas composition (H2/CH4 , Ar/CH4 and O2/CH4/H2), on the diamond-like carbon characteristics has been studied. Particular attention was focused on adhesion, environmental effects, IR(3–12 μm) transmission, coefficient of friction, and wear factors under spacelike environments of diamond-like carbon films on various substrates. A quadrupole mass spectrometer was utilized to monitor the ion beam composition for quality control and process optimization.

III-Nitride Growth on Lithium Niobate: A New Substrate Material for Polarity Engineering in III-Nitride Heteroepitaxy

2002 ◽  
Vol 743 ◽  
Author(s):  
W. Alan Doolittle ◽  
Gon Namkoong ◽  
Alexander Carver ◽  
Walter Henderson ◽  
Dieter Jundt ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Lattice Mismatch ◽  
Substrate Material ◽  
Buffer Layers ◽  
Initial Growth ◽  
Periodically Poled ◽  
Film Adhesion ◽  
Electro Optic ◽  
Bandgap Semiconductors ◽  
Aln Buffer

ABSTRACTHerein, we discuss the use of a novel new substrate for III-Nitride epitaxy, Lithium Niobate. It is shown that Lithium Niobate (LN) has a smaller lattice mismatch to III-Nitrides than sapphire and can be used to control the polarity of III-Nitride films grown by plasma assisted molecular beam epitaxy. Results from initial growth studies are reported including using various nitridation/buffer conditions along with structural and optical characterization. Comparisons of data obtained from GaN and AlN buffer layers are offered and details of the film adhesion dependence on buffer layer conditions is presented. Lateral polarization heterostructures grown on periodically poled LN are also demonstrated. While work is still required to establish the limits of the methods proposed herein, these initial studies offer the promise for mixing III-Nitride semiconductor materials with lithium niobate allowing wide bandgap semiconductors to utilize the acoustic, pyroelectric/ferroelectric, electro-optic, and nonlinear optical properties of this new substrate material as well as the ability to engineer various polarization structures for future devices.

scholarly journals Meyer-Rod Coated 2D Single-Crystalline Copper Nanoplate Film with Intensive Pulsed Light for Flexible Electrode

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 88
Author(s):  
Myeongjong Go ◽  
Asrar Alam ◽  
Ho Kwang Choie ◽  
Zhaoyang Zhong ◽  
Keun Hyung Lee ◽  
...  
Keyword(s):  
Systematic Study ◽  
Large Scale ◽  
Coating Process ◽  
Pulsed Light ◽  
Large Area ◽  
Flexible Electrode ◽  
Conductive Coatings ◽  
Single Crystalline ◽  
Rheological Behaviors ◽  
Industrial Coating

Copper is widely used because it is inexpensive, abundant, and highly conductive. However, most copper used in industrial coating processes is in the form of circular powder, which is problematic for large area, high conductive coatings. In this work, 2D single-crystalline Cu nanoplates (Cu NPLs) were synthesized and a systematic study on coating with large-scale Cu NPLs using a Meyer-rod coating process was performed. The rheological behaviors of the Cu solution with various concentrations, surface tensions, and speeds were analyzed using Ca and Re numbers to optimize coating conditions. In addition, the effect of intensive pulse light (IPL) to sinter the coper film within a 1 s timeframe was also investigated in order to be able to produce an electrode in the shortest possible time which is applicable to industry. Finally, the Meyer-rod coated electrode was utilized in an electrochemical luminescence (ECL) device.

Porous and Nanoporous Semiconductors and Emerging Applications

2005 ◽  
Vol 876 ◽  
Author(s):  
Helmut Föll ◽  
Jürgen Carstensen ◽  
Stefan Frey
Keyword(s):  
Optical Properties ◽  
Fuel Cells ◽  
Pore Formation ◽  
Large Area ◽  
Paper Briefly ◽  
High Explosives ◽  
Single Crystalline ◽  
Natural Materials ◽  
Porous Semiconductors ◽  
Wide Range

AbstractPores in single crystalline semiconductors can be produced in a wide range of geometries and morphologies, including the “nano” regime. Porous semiconductors may have properties completely different from the bulk, and metamaterials with e.g. optical properties not encountered in natural materials are emerging. Possible applications of porous semiconductors include various novel sensors, but also more “exotic” uses as, e.g. high explosives or electrodes for micro fuel cells. The paper briefly reviews pore formation (including more applied aspects of large area etching), properties of porous semiconductors and emerging applications.

Electrical resistance response of a ZnO single-crystalline substrate to trace ethanol under pulsed air jet irradiation

Vacuum ◽  
2020 ◽  
Vol 179 ◽  
pp. 109526 ◽  
Author(s):  
T.T. Suzuki ◽  
Y. Adachi ◽  
T. Ohgaki ◽  
I. Sakaguchi ◽  
M. Nakamura ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
Resistance Response ◽  
Single Crystalline ◽  
Air Jet ◽  
Crystalline Substrate
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