AlGaAs Surface Reconstruction after Cl2 Chemical Etch and Ultra High Vacuum Anneal

1994 ◽  
Vol 340 ◽  
Author(s):  
M. Hong ◽  
J. P. Mannaerts ◽  
L. H. Grober ◽  
F. A. Thiel ◽  
R. S. Freund
Keyword(s):  
Surface Reconstruction ◽  
Electron Cyclotron Resonance ◽  
Secondary Ion Mass Spectrometry ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Plasma Etch ◽  
Ecr Plasma ◽  
Chemical Etch

ABSTRACTWe report attaining (3x2) surface reconstruction with streaky reflection high energy electron diffraction (RHEED) patterns on Al0.4Ga0.6As after in-situ Cl2 chemical etch and ultra high vacuum (UHV) anneal. Secondary ion-mass spectrometry (SIMS) analysis at the regrown/etched Al0.4Ga0.6 As interface reveals impurities of O and C in the level of (5±1) × 1012 cm-2 and (3±1) × 1012 cm-2, respectively. These impurity levels are 10 times less than those of Al0.4Ga0.6 As after in-situ electron cyclotron resonance (ECR) plasma etch and UHV anneal without Cl2 chemical etch.

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.

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.

Characteristics and Recovery of SI Surfaces Plasma Etching in CHF3 / C2F6

1992 ◽  
Vol 259 ◽  
Author(s):  
H.-H. Park ◽  
K.-H. Kwon ◽  
B.-H. Koak ◽  
S.-M. Lee ◽  
O.-J. Kwon ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Silicon Surface ◽  
Secondary Ion Mass Spectrometry ◽  
High Vacuum ◽  
Silicon Layer ◽  
Ultra High Vacuum ◽  
Rapid Thermal Anneal ◽  
Condition C ◽  
Secondary Ion

ABSTRACTThe effects of SiO2 reactive ion etching (RIE) in CHF3 / C2F6 on the surface properties of the underlying Si substrate have been studied by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) techniques. The observed two major modifications are (i) a ∼50nm thick silicon layer which contains carbon and fluorine and (ii) 2∼3nm thick residue layer composed entirely of carbon, fluorine, oxygen and hydrogen on the silicon surface. The thermal behaviors of attributed peaks for C 1s, Si 2p, O 1s and F 1s of residue film have been analyzed after in-situ resistive anneal under ultra high vacuum (UHV) condition. C-F1, C-F2 and C-F3 bonds decompose and form C-CFx (x≤3) bonds above 200°C. Above 400°C, C-CFx bonds also decompose to C-C/H bonds. For recovery of the modified silicon surface, reactive ion etched specimens have been exposed to an oxygen plasma. By XPS analysis, the effect of an O2 plasma treatment has been revealed to be completed within 20min. With an O2 plasma pre-treated, a rapid thermal anneal (RTA) treatment as low as 500°2 is found to be effective for removal of impurities in the silicon.

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.

Vacuum Integrated Fabrication of Buried Heterostructure Edge Emitting Laser Diodes

1993 ◽  
Vol 300 ◽  
Author(s):  
M. Hong ◽  
D. Vahkshoori ◽  
L. H. Grober ◽  
J. P. Mannaerts ◽  
S. N. G. Chu ◽  
...  
Keyword(s):  
Electron Cyclotron Resonance ◽  
Laser Diodes ◽  
Surface Damage ◽  
Near Surface ◽  
Molecular Beam Epitaxial ◽  
Ecr Plasma ◽  
Native Oxides ◽  
Chemical Etch ◽  
Buried Heterostructure

ABSTRACTWe describe an in-situ fabrication process which combines electron cyclotron resonance (ECR) plasma H2 to clean native oxides, ECR SiCl4 to etch anisotropically, a brief Cl2 chemical etch to remove any near surface damage and contamination, and molecular beam epitaxial (MBE) regrowth. We report the first buried heterostructure (BH) AlGaAs/GaAs/InGaAs edge emitting laser diodes fabricated using this in-situ process. The lasers operate in continuous mode without noticeable degradation.

Si NWs Conversion to Si-SiC Core-Shell NWs by MBE

2015 ◽  
Vol 821-823 ◽  
pp. 965-969
Author(s):  
Fernando Lloret ◽  
D. Araujo ◽  
M.P. Villar ◽  
L. Liu ◽  
Konstantinos Zekentes
Keyword(s):  
Electron Microscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Si Nanowires ◽  
Transmission Electron ◽  
Set Up

Si nanowires (NWs) samples have been converted to silicon carbide (SiC) NWs at different conditions of substrate temperature in an ultra-high vacuum using a molecular beam epitaxy (MBE) set-up. Auger electron spectroscopy (AES) and reflection high-energy electron diffraction (RHEED) have been in-situ carried out to control the growth process. Scanning electron microscopy (SEM) and conventional transmission electron microscopy (CTEM) have been used to characterize the resulting nanostructures. In addition, the samples have been prepared by focused ion beam (FIB) in order to have electron-transparently lamellas for TEM with the interface nanowire-substrate. SiC/Si shell/core NWs free of planar defects have been obtained for conversion tmpratures lower than 800oC.

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.

In-Situ Study of the Oxide Mediated Epitaxy of CoSi2 on Si

1999 ◽  
Vol 564 ◽  
Author(s):  
M. W. Kleinschmit ◽  
M. Yeadon ◽  
J. M. Gibson
Keyword(s):  
Silicon Surface ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
High Energy Electron ◽  
In Situ Study ◽  
Intermediate Phases ◽  
Transmission Electron ◽  
Combined Imaging

AbstractOxide Mediated Epitaxy (OME) shows promise as a method to form good quality, thin epitaxial CoSi2 films on most Si surfaces. We have performed an in-situ study of the OME of CoSi2, on the Si (001) surface. Our work was carried out with our specially modified ultra-high vacuum transmission electron microscope (UHV TEM) SHEBA (Surface High Energy Electron Beam Apparatus). With SHEBA we were able to monitor the diffraction pattern and therefore the phase formation throughout the anneal. Our results confirm the suppression of intermediate phases during CoSi2 formation in the OME process. We also see a difference in the as deposited Co film when the oxide coated silicon surface is used rather than a clean substrate. From combined imaging and diffraction studies we will shed some light on the mechanism behind the success of OME.

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