Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Uniform growth of SiC single crystal thin films via a metal–Si alloy flux by vapour–liquid–solid pulsed laser deposition: the possible existence of a precursor liquid flux film

CrystEngComm ◽  
2016 ◽  
Vol 18 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Aomi Onuma ◽  
Shingo Maruyama ◽  
Takeshi Mitani ◽  
Tomohisa Kato ◽  
Hajime Okumura ◽  
...  
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Single Crystal ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Liquid Flux ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Interfacial Behaviour

3C-SiC single crystal films were successfully obtained in the PLD-based VLS process with a Si–Ni liquid flux, the interfacial behaviour of which was investigated by in situ high temperature laser microscopy in vacuum.

The Anomalous Rheed Patterns Observed from Ag-(111)Cu Bilayers

1974 ◽  
Vol 32 ◽  
pp. 480-481 ◽  
Author(s):  
C. T. Horng ◽  
R. W. Vook
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Cu Films ◽  
Bilayer Films ◽  
Residual Gas ◽  
Gas Pressures

Very smooth (111) single crystal Cu films (1200Å) were evaporated on NaCl/mica in an ultra-high vacuum RHEED system at residual gas pressures of less than 1×10−8 torr. These Cu films served as substrates for thin epitaxial monolayer Ag overgrowth. Film thicknesses were measured by a quartz thickness monitor. These Ag-(111)Cu bilayer films were formed and examined in-situ in the RHEED system and subsequently by TEM.

Heteroepitaxial Nucleation of Diamond

1995 ◽  
Vol 416 ◽  
Author(s):  
B. R. Stoner ◽  
P. J. Ellis ◽  
M. T. Mcclure ◽  
S. D. Wolter
Keyword(s):  
Single Crystal ◽  
Electronic Transport ◽  
Diamond Films ◽  
Heteroepitaxial Growth ◽  
Large Area ◽  
Diamond Nucleation ◽  
Single Crystal Diamond ◽  
Single Crystal Films ◽  
Crystal Films

ABSTRACTThe heteroepitaxial nucleation and eventual growth of large area single crystal diamond films has long eluded researchers interested in tapping it's many enabling properties, specifically in the field of active electronics. The uncertainty surrounding the diamond nucleation mechanism(s) and corresponding inability to carefully control this process are often blamed for the difficulty in achieving true heteroepitaxial growth. Biasenhanced nucleation (BEN) has been shown to provide in-situ control of the nucleation process. Subsequent advancements in both nucleation and deposition stages has resulted in highly oriented diamond films, approaching single crystal quality yet still plagued by arrays of medium to low angle grain boundaries that can degrade the electronic transport properties. To further improve upon these results and achieve large area, single crystal films it is believed that development must focus on the more fundamental problems of diamond nucleation. This paper presents a review of recent progress pertaining to the bias-enhanced process and focuses on data specific to the epitaxial nucleation dilemma.

Heteroepitaxial Growth of MgO Films on NiO(100) Single Crystal Surfaces

1994 ◽  
Vol 357 ◽  
Author(s):  
S. Imaduddin ◽  
A.M. Davidson ◽  
R.J. Lad
Keyword(s):  
Single Crystal ◽  
Lattice Mismatch ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Heteroepitaxial Growth ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Oxygen Anions ◽  
Mgo Layers

AbstractEpitaxial MgO layers were grown on cleaved NiO(100) single crystal surfaces. The less than 1% lattice mismatch between MgO and NiO allows almost ideal epitaxy of MgO at 100°C. The epitaxial films were created by dosing Mg onto stoichiometric NiO(100) both in ultra-high vacuum (UHV) and in an O2 atmosphere (5×10−7 Torr). Chemical interactions at the resulting interfaces were studied using XPS. When Mg is dosed onto NiO(100) in UHV, MgO forms by interacting with oxygen anions in the NiO substrate thereby reducing the nickel cations. Metallic Mg layers begin to form upon subsequent dosing. When Mg is deposited in O2, epitaxial MgO(100) layers grow to a thickness of at least 50Å as confirmed by in situ RHEED and LEED observations. Negligible intermixing between the MgO and NiO is observed during growth at 100°C and on subsequent annealing in UHV up to 600°C.

Ge Optical Interconnects on a GaAs Surface

1994 ◽  
Vol 340 ◽  
Author(s):  
M. Dubey ◽  
G.F. McLane ◽  
K.A. Jones ◽  
R.T. Lareau ◽  
D.W. Eckart ◽  
...  
Keyword(s):  
Optical Interconnects ◽  
High Vacuum ◽  
Amorphous Film ◽  
Ultra High Vacuum ◽  
Free Carrier Absorption ◽  
Sputtering Deposition ◽  
A Value ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Carrier Absorption

ABSTRACTGermanium films were deposited on GaAs (100) substrates at temperatures between room temperature (RT) and 500°C using ultra high vacuum (UHV) E-beam and sputtering deposition methods. The Ge film deposited in UHV at 100°C was amorphous and had a flat absorbance curve over the range investigated, 4000 - 500 cm-1, with a value of 0.03 at 1000 cm1 (10μm). Films deposited by E-beam at RT and 50°C had comparably low absorbances, but they contained a peak at 830 cm-1, which was possibly due to absorption by a Ge-O bond. The amorphous film deposited at 150°C and the single crystal films deposited at 400 and 500°C by E-beam had larger absorbances caused by free carrier absorption. The amorphous Ge sputtered film deposited at RT had a relatively low absorbance, but it contained the absorption peak attributed to Ge-O. The absorbance increased dramatically when it was annealed at 400 or 500°C due to the rapid out diffusion of Ga and As through the relatively open structure.

Hetero-Epitaxy of Group Va Metals on Sapphire

1972 ◽  
Vol 30 ◽  
pp. 492-493
Author(s):  
J. E. O'Neal ◽  
J. J. Bellina ◽  
B. B. Rath
Keyword(s):  
Thermal Contact ◽  
High Vacuum ◽  
Electron Beam Evaporation ◽  
Ultra High Vacuum ◽  
Backing Plate ◽  
Sapphire Substrates ◽  
Deposition Parameters ◽  
Polishing Damage ◽  
Reflection Electron Diffraction

Thin films of the bcc metals vanadium, niobium and tantalum were epitaxially grown on (0001) and sapphire substrates. Prior to deposition, the mechanical polishing damage on the substrates was removed by an in-situ etch. The metal films were deposited by electron-beam evaporation in ultra-high vacuum. The substrates were heated by thermal contact with an electron-bombarded backing plate. The deposition parameters are summarized in Table 1.The films were replicated and examined by electron microscopy and their crystallographic orientation and texture were determined by reflection electron diffraction. Verneuil-grown and Czochralskigrown sapphire substrates of both orientations were employed for each evaporation. The orientation of the metal deposit was not affected by either increasing the density of sub-grain boundaries by about a factor of ten or decreasing the deposition rate by a factor of two. The results on growth epitaxy are summarized in Tables 2 and 3.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Nucleation and initial growth of Pd2Si crystals on Si(111)

1993 ◽  
Vol 51 ◽  
pp. 844-845
Author(s):  
Xianghong Tong ◽  
Oliver Pohland ◽  
J. Murray Gibson
Keyword(s):  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Initial Growth ◽  
Surface And Interface ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Initial Stage ◽  
Effect Of Surface

The nucleation and initial stage of Pd2Si crystals on Si(111) surface is studied in situ using an Ultra-High Vacuum (UHV) Transmission Electron Microscope (TEM). A modified JEOL 200CX TEM is used for the study. The Si(111) sample is prepared by chemical thinning and is cleaned inside the UHV chamber with base pressure of 1x10−9 τ. A Pd film of 20 Å thick is deposited on to the Si(111) sample in situ using a built-in mini evaporator. This room temperature deposited Pd film is thermally annealed subsequently to form Pd2Si crystals. Surface sensitive dark field imaging is used for the study to reveal the effect of surface and interface steps.The initial growth of the Pd2Si has three stages: nucleation, growth of the nuclei and coalescence of the nuclei. Our experiments shows that the nucleation of the Pd2Si crystal occurs randomly and almost instantaneously on the terraces upon thermal annealing or electron irradiation.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

Modifications of a JEOL 2000EX TEM for insSitu surface studies

1993 ◽  
Vol 51 ◽  
pp. 640-641
Author(s):  
Michael T. Marshall ◽  
Xianghong Tong ◽  
J. Murray Gibson
Keyword(s):  
Electron Diffraction ◽  
Surface Science ◽  
Film Growth ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Transmission Electron ◽  
Fundamental Insight

We have modified a JEOL 2000EX Transmission Electron Microscope (TEM) to allow in-situ ultra-high vacuum (UHV) surface science experiments as well as transmission electron diffraction and imaging. Our goal is to support research in the areas of in-situ film growth, oxidation, and etching on semiconducter surfaces and, hence, gain fundamental insight of the structural components involved with these processes. The large volume chamber needed for such experiments limits the resolution to about 30 Å, primarily due to electron optics. Figure 1 shows the standard JEOL 2000EX TEM. The UHV chamber in figure 2 replaces the specimen area of the TEM, as shown in figure 3. The chamber is outfitted with Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), Residual Gas Analyzer (RGA), gas dosing, and evaporation sources. Reflection Electron Microscopy (REM) is also possible. This instrument is referred to as SHEBA (Surface High-energy Electron Beam Apparatus).The UHV chamber measures 800 mm in diameter and 400 mm in height. JEOL provided adapter flanges for the column.

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