Photoemission Study of the Si, Ge Epitaxial Growth Process Using Surfactants

1992 ◽  
Vol 259 ◽  
Author(s):  
Xiaoyu Yang ◽  
Renyu Cao ◽  
Jeff Terry ◽  
Piero Pianetia
Keyword(s):  
Free Energy ◽  
Growth Process ◽  
Room Temperature ◽  
Energy Deposition ◽  
Low Energy ◽  
Heteroepitaxial Growth ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Photoemission Study

ABSTRACTHeteroepitaxial growth of Ge on Si(100) and Si on Ge(100) surfaces with Sb as a surfactant has been investigated by in situ high resolution photoemission and low energy electron diffraction (LEED). Our results show that an ordered monolayer of Sb atoms saturate the surface dangling bonds and consequently lower the surface free energy. Deposition of Ge or Si on the Sb/Si(100) or Sb/Ge(100) surfaces either at room temperature, followed by mild annealing or deposition at elevated temperature, result in an epitaxial layer of Ge or Si on the substrate, respectively. We provide clear experimental evidence that the deposited Ge or Si atoms changes position with the surface Sb atoms in this process. Ge or Si atoms occupy the epitaxial sites previously occupied by the Sb atoms. The Sb atoms in turn segregate to the surface and form a new ordered layer. The Bi-assisted growth process is also discussed.

In-Situ Studies of the Formation of GA and AL Wires on SI(112) Facet Surfaces

1999 ◽  
Vol 570 ◽  
Author(s):  
S.M. Prokes ◽  
O.J. Glembocki
Keyword(s):  
Light Scattering ◽  
Electron Diffraction ◽  
Rapid Change ◽  
Low Energy ◽  
Chemical Sensitivity ◽  
Low Energy Electron Diffraction ◽  
Sequential Deposition ◽  
Low Energy Electron ◽  
Metallic Wires

ABSTRACTReflectance difference anisotropy (RDA) and low energy electron diffraction (LEED)have been used to study the formation of Ga or Al chains and nanowires on the Si(112) surface. At T > 350°C, the Ga or Al chains form at the step edges by a self-limiting process, while at lower temperatures, Ga or Al nanowires form on the terraces in addition to the chains on the ledges. The process has been tracked in real time from the rapid change of the (2×1) Si(112) reconstruction under subcritical coverage to chain formation leading to a 5×1 reconstruction followed by a 6×1 reconstruction’. During sequential deposition of Ga and Al, we observe (in RDA and AES) that Ga atoms forming the chains can be replaced by Al, indicating a stronger Al-Si bond strength and confirming the chemical sensitivity of the light scattering in RDA. Low temperature depositions (in the 300’C range) are shown to lead to the formation of Al (or Ga) metallic wires on the Si(111) terraces. Continued deposition of less than 10 monolayers at T below 250°C leads to a very anisotropic but patterned Al or Ga structure in registry with the substrate which retains an unexpectedly large polarizability for coverages as thick as 40 ml.

Surface Reactions During the Deposition of Ge from Chemical Sources on Ge(100)-(2×1)

1996 ◽  
Vol 448 ◽  
Author(s):  
C. Michael Greenlief ◽  
Jihong Chen
Keyword(s):  
Room Temperature ◽  
Isotopic Labeling ◽  
Low Energy ◽  
Surface Processes ◽  
Elimination Reaction ◽  
Reaction Step ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Hydride Elimination

AbstractThe adsorption and decomposition of diethylgermane, triethylgermane, and digermane on the Ge(100) surface are investigated with the intent of elucidating the surface processes leading to the deposition of epitaxial Ge films. Room temperature adsorption of diethylgermane or triethylgermane leads to the formation of surface germanium hydrides and ethyl groups. The ethyl groups decompose at higher temperatures and form ethylene via a β-hydride elimination reaction. Isotopic labeling experiments are used to confirm this reaction step. This is in contrast to the Si(100) surface where both α- and β-hydride elimination is observed for the decomposition of surface ethyl groups. The adsorption and reaction of digermane with the Ge surface is also determined to help provide a comparison with the ethylgermanes. Low energy electron diffraction is used to evaluate the quality of the deposited germanium films.

Studies on surfaces of Zr(0001) that contain oxygen and show (2 × 2)-type low-energy electron diffraction patterns

1987 ◽  
Vol 65 (5) ◽  
pp. 464-467 ◽  
Author(s):  
P. C. Wong ◽  
K. A. R. Mitchell
Keyword(s):  
Electron Diffraction ◽  
Room Temperature ◽  
Low Energy ◽  
Energy Electron ◽  
Leed Pattern ◽  
Low Energy Electron Diffraction ◽  
Adsorption Sites ◽  
Low Energy Electron ◽  
Low Exposure ◽  
Diffraction Patterns

Oxygen chemisorption on the Zr(0001) surface has been studied in the low-exposure regime with Auger electron spectroscopy and measurements of the width of a half-order low-energy electron diffraction (LEED) beam. The new observations and conclusions are as follows. (i) The diffusion of O atoms to the bulk effectively starts at around 236 °C. (ii) Oxygen adsorbs in a disordered state at room temperature and orders sufficiently to show a (2 × 2)-type LEED pattern on heating to 220 °C. (iii) With increasing O exposure, 1/4, 1/2, and 3/4 of the available adsorption sites can be systematically filled, while showing the apparent (2 × 2)-LEED pattern, prior to the establishment of an ordered (1 × 1)-O surface. (iv) The process in (iii) can be reversed by starting with the (1 × 1)-O surface and heating above 236 °C.

AN ORDERED MIXED STRUCTURE FORMED BY RESTRUCTURING TYPE COADSORPTION OF Na AND K ON Ag(001)

2001 ◽  
Vol 08 (06) ◽  
pp. 653-659 ◽  
Author(s):  
SEIGI MIZUNO ◽  
MASAO IMAKI ◽  
HIROSHI TOCHIHARA
Keyword(s):  
Electron Diffraction ◽  
Room Temperature ◽  
Low Energy ◽  
Energy Electron ◽  
Mixed Structure ◽  
Leed Pattern ◽  
Low Energy Electron Diffraction ◽  
Site Selectivity ◽  
Low Energy Electron

Coadsorption of Na and K on Ag(001) at room temperature has been studied by low energy electron diffraction (LEED). A 3 × 3 LEED pattern was observed irrespective of the order of adsorption. For this formation, it is necessary to deposit Na and K atoms with appropriate coverage. We have determined the 3 × 3 structure by a tensor LEED analysis. It is a restructured surface and is very similar to the previously determined 3 × 3 structure formed on Ag(001) by pure Na adsorption. In the coadsorption, Na and K atoms occupy preferable sites selectively, and construct an ordered mixed structure on Ag(001). That is, small Na atoms are located in the missing row sites, while large K atoms sit on the hollow sites of four-Ag-atom islands. The reason for the site selectivity of Na and K atoms in the mixed 3 × 3 structures is discussed.

Adsorbed Structures of Ba on Si(110) Surfaces Studied by LEED and STM

2003 ◽  
Vol 10 (02n03) ◽  
pp. 467-472 ◽  
Author(s):  
Y. Sakamoto ◽  
Y. Fukui ◽  
J. Takeuchi ◽  
S. Hongo ◽  
T. Urano ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Room Temperature ◽  
Periodic Structures ◽  
Low Energy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron Diffraction ◽  
Annealing Temperatures ◽  
Unit Structure ◽  
Low Energy Electron

Adsorbed structures of barium on Si(110) surfaces have been studied by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). Several structures of "10 × 1," "12 × 2," 11 × 6 and streaky 4 × n were observed by LEED at annealing temperatures of about 775°C, 800°C, 900°C and 1100°C, respectively, after a-few-monolayer deposition of Ba at room temperature. In the STM experiment periodic structures of "10 × 6" and 11 × 6, and a rearrangement of pentagon pairs which is the unit structure seen on the terrace for the clean Si(110) "16 × 2" surface, were observed.

THE SURFACE STRUCTURES OF Pd(100)-(1×1) AND c(2×2)-K

1996 ◽  
Vol 03 (03) ◽  
pp. 1339-1343 ◽  
Author(s):  
J. BURCHHARDT ◽  
E. LUNDGREN ◽  
M.M. NIELSEN ◽  
J.N. ANDERSEN ◽  
D.L. ADAMS
Keyword(s):  
Quantitative Analysis ◽  
Electron Diffraction ◽  
Hard Sphere ◽  
Room Temperature ◽  
Interlayer Spacing ◽  
Low Energy ◽  
Surface Structures ◽  
Low Energy Electron Diffraction ◽  
Sphere Radius ◽  
Low Energy Electron

The surface structure of the Pd (100)- c (2×2)-K phase formed by adsorption of K at room temperature has been determined by quantitative analysis of low-energy electron-diffraction (LEED) intensity-energy measurements. K atoms occupy four-fold hollow sites on a slightly perturbed substrate. The vertical distance between the K layer and the first Pd layer is determined to be 2.13±0.06 Å, which corresponds to an effective hard-sphere radius of 1.83 Å for the adsorbed K atoms. The second Pd layer is rumpled with a splitting of 0.04 Å between two bilayers. An analysis of LEED intensities measured for the clean Pd(100) surface confirms previous reports of an expansion of the first interlayer spacing. Adsorption of K in the c (2×2) structure results in a reduction of this expansion from 5% to 1%.

HUGE MAGNETOVOLUME EFFECT IN AN INVERTED Mn LAYER ON Ag(001) STUDIED BY LEED

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1431-1436 ◽  
Author(s):  
P. SCHIEFFER ◽  
C. KREMBEL ◽  
M.-C. HANF ◽  
G. GEWINNER ◽  
Y. GAUTHIER
Keyword(s):  
Room Temperature ◽  
High Spin State ◽  
Low Energy ◽  
Dimensional Structure ◽  
Low Energy Electron Diffraction ◽  
Magnetovolume Effect ◽  
Small Contraction ◽  
Low Energy Electron ◽  
Atomic Radii ◽  
The Ideal

The surface structure obtained by deposition of a Ag monolayer on the ideal c(2 × 2) antiferromagnetic Mn monolayer on Ag(001) at 100 K and subsequent annealing at room temperature is determined by low energy electron diffraction. It is established that this system is actually a good realization of an inverted monolayer, i.e. a pseudomorphic Ag/Mn/Ag(001) structure that corresponds to a reversed composition of the two topmost layers with respect to the Mn overlayer. The Ag–Mn and Mn–Ag interlayer distances, d12 = 1.97 ± 0.015 Å and d23 = 1.97 ± 0.02 Å respectively, indicate only a fairly small contraction of ~ 3.5% (~ 1.5%) with respect to the ideal Ag bulk lattice (Mn monolayer on top) as compared to ~ 10% expected from atomic radii in bulk Mn and Ag. This clearly reveals a spectacular magnetovolume effect related to the high spin state of Mn in this two-dimensional structure.

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