In-Situ Transmission Electron Microscopy of the Etching of Silicon (111) Surfaces by Oxygen

1991 ◽  
Vol 238 ◽  
Author(s):  
J. M. Gibson ◽  
F. M. Ross

ABSTRACTSilicon (111) surfaces have been etched in-situ in a ultra-high vacuum transmission electron microscope. Surface steps are observed to flow during etching, so that Si atoms are removed only from steps. This is in contrast to the behavior during the formation of an oxide layer reported previously. The nucleation of steps and their interaction with surface impurities is described.

Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove

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.


2001 ◽  
Vol 7 (6) ◽  
pp. 486-493 ◽  
Author(s):  
Judith C. Yang ◽  
Mridula D. Bharadwaj ◽  
Guangwen Zhou ◽  
Lori Tropia

AbstractWe review our studies of the initial oxidation stages of Cu(001) thin films as investigated by in situ ultra-high vacuum transmission electron microscopy. We present our observations of surface reconstruction and the nucleation to coalescence of copper oxide during in situ oxidation in O2. We have proposed a semi-quantitative model, where oxygen surface diffusion is the dominant mechanism of the initial oxidation stages of Cu. We have also investigated the effect of water vapor on copper oxidation. We have observed that the presence of water vapor in the oxidizing atmosphere retards the rate of Cu oxidation and Cu2O is reduced when exposed directly to steam.


2005 ◽  
Vol 20 (7) ◽  
pp. 1684-1694 ◽  
Author(s):  
Guangwen Zhou ◽  
Judith C. Yang

The initial oxidation stages of Cu(100), (110), and (111) surfaces have been investigated by using in situ ultra-high-vacuum transmission electron microscopy (TEM) techniques to visualize the nucleation and growth of oxide islands. The kinetic data on the nucleation and growth of oxide islands shows a highly enhanced initial oxidation rate on the Cu(110) surface as compared with Cu(100), and it is found that the dominant mechanism for the nucleation and growth is oxygen surface diffusion in the oxidation of Cu(100) and (110). The oxidation of Cu(111) shows a dramatically different behavior from that of the other two orientations, and the in situ TEM observation reveals that the initial stages of Cu(111) oxidation are dominated by the nucleation of oxide islands at temperatures lower than 550 °C, and are dominated by two-dimensional oxide growth at temperatures higher than 550 °C. This dependence of the oxidation behavior on the crystal orientation and temperature is attributed to the structures of the oxygen-chemisorbed layer, oxygen surface diffusion, surface energy, and the interfacial strain energy.


1990 ◽  
Vol 202 ◽  
Author(s):  
M.A. Lawn ◽  
R.G. Elliman ◽  
M.C. Ridgway ◽  
R. Leckey ◽  
J.D. Riley

ABSTRACTA study of the growth of thin Ir silicide films on (111)Si substrates has been undertaken. Thin (2.0nm) ir films deposited onto Si substrates under ultra-high vacuum conditions have been observed to display remarkable film continuity and fine grain structure (lnm). In situ annealing at 1000°C resulted in the formation of large regions (>10µm) of epitaxial IrSi3 islands (∼1µm) with identical epitaxial orientations. By means of annealing an as-deposited (2.0nm) Ir film stepwise to 1000°C within a transmission electron microscope the evolution of Ir silicide phases and morphologies were observed. The epitaxial growth of the semiconducting IrSi1.75 phase is reported along with the formation of Ir silicide islands at temperatures between 700°C and 800°C.


2005 ◽  
Vol 20 (7) ◽  
pp. 1910-1917 ◽  
Author(s):  
L. Sun ◽  
J.C. Yang

The nucleation and growth of Cu2O islands due to Cu(100) oxidation at temperatures from 200 to 350 °C have been observed by in situ ultra-high-vacuum transmission electron microscopy. For this temperature range, epitaxial Cu2O islands form a triangular shape with rounded edges when Cu(100) is exposed to dry oxygen at 5 × 10−4 Torr in situ. Our initial analysis on the nucleation and growth of these three-dimensional Cu2O islands agrees well with the heteroepitaxial model of surface diffusion of oxygen.


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