Silicon Homoepitaxy at 300°C Using ArF Excimer Laser Photolysis of Disilane

1990 ◽  
Vol 201 ◽  
Author(s):  
B. Fowler ◽  
T. Lian ◽  
D. Bullock ◽  
S. Banerjee
Keyword(s):  
Electron Diffraction ◽  
Excimer Laser ◽  
Growth Rates ◽  
Defect Density ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Arf Excimer Laser

AbstractPhotolysis of Si2H6 by an ArF excimer laser has been used to deposit Si homoepitaxial layers at temperatures as low as 300°C. The chemical vapor deposition process at growth rates from 0.5-4 Å/minute is performed in an ultra-high vacuum chamber which, along with an ex situ HF dip and a novel in situ hydrogen clean using laser excitation, results in minimization of oxygen and carbon contamination which inhibits Si epitaxy. The growth involves photolytic decomposition of Si2H6 and the generation and adsorption of SiH2 precursors on the hydrogenated Si surface, which is the rate limiting step. Growth rates are observed to vary proportionally with laser power. Very low defect density films in terms of stacking faults and dislocation loops (less than 105 cm−2), and excellent crystallinity have been deposited as confirmed by Schimmel etching and Nomarski microscopy, transmission electron microscopy, electron diffraction and in situ reflection high energy electron diffraction.

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.

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.

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.

Self-assembled Ge quantum dots on SiC substrates grown by UHV-CVD

2002 ◽  
Vol 742 ◽  
Author(s):  
C. Calmes ◽  
V. Le ◽  
D. Bouchier ◽  
S. E. Saddow ◽  
V. Yam ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Vacuum ◽  
Chemical Vapor ◽  
High Energy ◽  
Surface Cleaning ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
First Results ◽  
Ge Quantum Dots

AbstractWe report our first results using a ultra high vacuum chemical vapor deposition (UHV-CVD) system to form Ge quantum dots on off-axis SiC substrates. Pure SiH4 and hydrogen-diluted GeH4 were used as gas precursors. The SiC substrates were chemically cleaned using the modified RCA process and the SiO2 layer was removed in-situ under a low SiH4 flow rate at a temperature between 1030°C and 1080°C. The Ge quantum dots were grown at a temperature of 750°C. In-situ reflection high-energy electron diffraction (RHEED) was used to monitor the surface cleaning and the Ge quantum dot growth. Ex-situ scanning electron microscope and atomic force microscopy were used to confirm the presence of Ge dots. The observed dots are smaller (350 Å width and 100 Å height) than similar Ge dots grown on Si.

A Mechanism of Sliding on the Nanometer-Thick Ag Layers

2005 ◽  
Author(s):  
F. Honda ◽  
M. Goto
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
High Vacuum ◽  
High Energy ◽  
Thin Layers ◽  
Ultra High Vacuum ◽  
Wear And Friction ◽  
Thickness Measurements

Tribological performance of sub-nano to nanometer-thick Ag layers deposited on Si(111) have been examined to understand the role of surface thin layers to the wear and friction characteristics. The slider was made of diamond sphere of 3 mm in radius. Sliding tests were carried out in an ultra-high vacuum environment (lower than 4 × 10−8 Pa) and analyzed in-situ by Auger electron spectroscopy (AES) for the quantitative thickness-measurements, by reflection high-energy electron diffraction (RHEED) to clarify the substrate cleanliness and crystallography of the Ag films, and by scanning probe microscopy (SPM) for the morphology of the deposited/slid film surfaces. As the results, a minimum of the friction coefficient 0.007 was observed from the film thickness range of 1.5–10 nm, and exactly no worn particles were found after 100 cycles of reciprocal sliding. Results have directly indicated that solid Ag(111) sliding planes allowed to reduce the friction coefficient very low without any detectable wear particles, and Ag nanocrystallites in Ag polycrystalline layers increase the size to 20–40 nm order, during sliding. The friction coefficient was slightly dependent to the normal load. Results were discussed on the role of the surface atoms to the friction, and a mechanism of sliding on Ag thin layers.

Effects of Phosphorus Exposure on Arsenic-Stabilized GaAs 2×4 Surface

1993 ◽  
Vol 312 ◽  
Author(s):  
A. H. Bensaoula ◽  
A. Freundlich ◽  
A. Bensaoula ◽  
V. Rossignol
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Growth Process ◽  
High Energy ◽  
Ex Situ ◽  
Chemical Beam Epitaxy ◽  
High Energy Electron ◽  
X Ray Diffraction ◽  
X Ray

AbstractPhosphorus exposed GaAs (100) surfaces during a Chemical Beam Epitaxy growth process are studied using in-situ Reflection High Energy Electron Diffraction and ex-situ High Resolution X-ray Diffraction. It is shown that the phosphorus exposure of a GaAs (100) surface in the 500 – 580 °C temperature range results in the formation of one GaP monolayer.

In situ quantitative analysis of GeXSi1-X alloys during growth by reflection EELS

1991 ◽  
Vol 49 ◽  
pp. 878-879
Author(s):  
Shouleh Nikzad ◽  
Channing C. Ahn ◽  
Harry A. Atwater
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Film Growth ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Mbe Growth ◽  
Electron Microscopes ◽  
Electron Energy Loss

The universality of reflection high energy electron diffraction (RHEED) as a structural tool during film growth by molecular beam epitaxy (MBE) brings with it the possibility for in situ surface chemical analysis via spectroscopy of the accompanying inelastically scattered electrons. We have modified a serial electron energy loss spectrometer typically used on an electron microscope to work with a 30 keV RHEED-equipped MBE growth chamber in order to determine the composition of GexSi1-x alloys by reflection electron energy loss (REELS) experiments. Similar work done in transmission electron microscopes has emphasized the surface sensitivity of this technique even though these experiments have never been done under ultra-high vacuum conditions. In this work, we are primarily concerned with the accuracy with which core losses can be used to determine composition during MBE growth.

scholarly journals Stm at High Temperature: What you see is what you see … usually

1993 ◽  
Vol 1 (5) ◽  
pp. 4-4
Author(s):  
Michael M. Kersker
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
High Vacuum ◽  
High Energy ◽  
Atomic Level ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Scanning Probe ◽  
Sem Images ◽  
Optical Discs

There remains two basic axioms of all microscopists: the first….if you look, you're bound to see something, and the second….not everything you will see is artifact. These axioms apply particularly well to scanning probe microscopy at the molecular and atomic level. Fortunately, coarser resolution images share comforting similarities with images from other established scanning methods. Holes in optical discs look like holes when probed with AFM tips, and these holes look very much like SEM images, a subject with which we have some familiarity. At the molecular and atomic level, however, the scanning probe instruments may or may not be “seeing” the sample, though they are clearly seeing something.Comparison of surface structure observed with indirect surface structural measurements, for example by LEED (Low Energy Electron Diffraction) or RHEED (Reflection High Energy Electron Diffraction) usually under ultra-high vacuum conditions can lead, by inference, to an understanding of the real bulk or average surface structure.

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