Depth-Selective Investigation of Fe-Silicides Formed After Molecular Beam Epitaxy, Using Conversion Electron MÖSsbauer Spectrometry.

1994 ◽  
Vol 337 ◽  
Author(s):  
S. Degroote ◽  
T. Kobayashi ◽  
J. Dekoster ◽  
A. Vantomme ◽  
G. Langouche
Keyword(s):  
Conversion Electron ◽  
Room Temperature ◽  
Molecular Beam ◽  
Mössbauer Spectrometry ◽  
Silicide Formation ◽  
Iron Silicides ◽  
Annealing Temperatures ◽  
Sample Composition ◽  
Mossbauer Spectrometry

ABSTRACTFe-Silicides were formed by annealing MBE-deposited thin Fe layers with a thickness in the range of 24 Å on (7x7) reconstructed Si(l11) substrates. Samples suitable for depth-selective investigations by CEMS (Conversion Electron Mössbauer Spectrometry) were prepared by using only the 57Fe isotope for a few monolayers of the total Fe film, and depositing these selectively right at the interface or separated from it. During the growth the substrate was held at room temperature. The silicide formation upon annealing to temperatures up to 900°C was monitored in situ with RHEED. From the CEMS studies a drastically different sample composition was inferred as a function of monolayer distance from the interface for the as-deposited samples and for annealing temperatures up to 400°C. Analysis of these spectra indicates the presence of metastable and stable iron silicides.

Tem Investigation of Co-Si Thin Films on S1-xGex/Si

1998 ◽  
Vol 4 (S2) ◽  
pp. 630-631
Author(s):  
A. F. Myersa ◽  
P. T. Goeller ◽  
E. B. Steel ◽  
B. I. Boyanov ◽  
D. E. Sayers ◽  
...  
Keyword(s):  
Room Temperature ◽  
Molecular Beam ◽  
Contact Material ◽  
Silicide Formation ◽  
Cobalt Disilicide ◽  
Annealing Temperatures ◽  
Microscopy Investigation ◽  
Electron Microscopy Investigation ◽  
Phosphorus Doped ◽  
Thermal And Chemical Stability

Cobalt disilicide (CoSi2) is an attractive contact material for Si1-xGex devices due to its low resistivity, low Schottky barrier, and good thermal and chemical stability. Previous studies have shown that blanket Co films on Si0.80Ge0.20 react at annealing temperatures of 700 °C to form CoSi, CoSi2 and a Ge-rich Si1-xGex alloy; no Co-Ge phases were found. The Co preferentially reacts with the Si, which can lead to Ge segregation and island formation. To gain a better understanding of cobalt silicide formation, an electron microscopy investigation of Co/Si1-xGex/Si was performed.Si1-xGex films (x ≤ 0.3) 64 nm to 260-nm thick were grown by molecular beam epitaxy at 550 °C on phosphorus-doped Si <001> substrates. Co films ranging in thickness from 5 nm to 25 nm were electron-beam evaporated (evaporator base pressure < 6.67 x 10-8 Pa) at room temperature on the Si1-xGex films.

Fe-Silicides Formed with Molecular Beam Epitaxy and Studied with Conversion Electron Mössbauer Spectroscopy

1993 ◽  
Vol 320 ◽  
Author(s):  
S. Degroote ◽  
M.H. Langelaar ◽  
T. Kobayashi ◽  
J. Dekoster ◽  
J. De Wachter ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Conversion Electron ◽  
Room Temperature ◽  
Mossbauer Spectroscopy ◽  
Ex Situ ◽  
Silicide Formation ◽  
Conversion Electron Mössbauer Spectroscopy ◽  
Mößbauer Spectroscopy ◽  
Conversion Electron Mossbauer Spectroscopy

ABSTRACTFe-sulicides were formed by annealing MBE-deposited thin 57Fe layers with thicknesses between 20 Å and 60 Å on (7x7) reconstructed Si(111) substrates. During the growth the substrate was held at room temperature. The silicide formation upon annealing in the temperature range of 200°C to 900°C was studied in-situ with RH-EED. Samples were studied with in-situ CEMS (Conversion Electron Mossbauer Spectroscopy) as well as with ex-situ CEMS after covering with Ag to prevent oxidation. RBS/Channeling was used to study the epitaxial quality and the structure of these layers.Using the 57Fe nuclear probe, it is shown that silicide formation occurs at the interface already at room temperature. Metastable silicides with cubic structure are observed in the low temperature annealing range, and characterized by their Mossbauer parameters. At higher temperatures stable ε-FeSi and β-FeSi2 are formed.

In-situ Measurement of GaAs Optical Constants and Surface Quality, as Functions of Temperature

1991 ◽  
Vol 222 ◽  
Author(s):  
Huade Yao ◽  
Paul G. Snyder
Keyword(s):  
Room Temperature ◽  
Optical Constants ◽  
Molecular Beam ◽  
Elevated Temperatures ◽  
Native Oxide ◽  
Time Data ◽  
Gaas Sample ◽  
Optical Thermometer ◽  
Surface Changes

ABSTRACTIn-situ spectroscopic ellipsometry (SE) was applied to monitor GaAs (100) surface changes induced at elevated temperatures inside an ultrahigh vacuum (UHV) chamber (<1×10−9 torr base pressure, without As overpressure). The real time data showed clearly the evolution of the native-oxide desorption at ∼577°C, on a molecular-beam-epitaxy (MBE)-grown GaAs (100) surface. In addition, surface degradation was found before and after the oxide desorption. A clean and smooth surface was obtained from an arsenic-capped, MBE-grown GaAs sample, after the arsenic coating was evaporated at ∼350 °C inside the UHV. Pseudodielectric functions <ε>GaAs, from 1.6 eV to 4.5 eV, were obtained through the SE measurements, from this oxide-free surface, at temperatures ranging from room temperature (RT) to ∼610 °C. These <ε> data were used as reference data to develop an algorithm for determining surface temperatures from in-situ SE measurements, thus turning the SE instrument into a sensitive optical thermometer.

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