UHV-TEM imaging and diffraction study of Cu-Au on Si(111)

1992 ◽  
Vol 50 (1) ◽  
pp. 328-329
Author(s):  
P. Xu ◽  
L. D. Marks
Keyword(s):  
Surface Science ◽  
Ion Beam ◽  
High Vacuum ◽  
Sample Surface ◽  
Ultra High Vacuum ◽  
Electron Gun ◽  
Stable Operation ◽  
Thin Sample ◽  
Specimen Holder ◽  
Transmission Electron

It has been demonstrated that ultra-high vacuum transmission electron microscopy is a powerful technique in solving surface atomic structures. During some recent work while we were testing surface imaging modes using the Si(111)-7×7 surface, we accidentally contaminated the surface by sputtering copper and some gold from the specimen holder onto the silicon. This paper presents the results of transmission electron diffraction and imaging studies of this surface.Experiments were performed in a Hitachi UHV H-9000 300 keV electron microscope with a stable operation pressure of 1x10-10 Torr. Attached to the microscope is a UHV surface science chamber for in situ sample preparation. A thin sample of silicon (111) (P doped to 80 ohm-cm) was mechanically polished, dimpled, and ion-beam thinned before being transferred into the surface science chamber. The sample was then ion beam sputter cleaned using 3-4 Kv argon ions and annealed to about 600°C using an electron gun (4-5 Kv, 2-3 Ma). Later tests indicated that the ion gun was not centered around the 3 mm disk and a part of the sample surface was covered by the sputtered materials from the sample holder. EDX results from a Hitachi HF-2000 analytical microscope showed that the deposited layer consisted of about 70% Cu and 30% Au.

UHV-TED study of clean Si(100) surface structures

1993 ◽  
Vol 51 ◽  
pp. 1002-1003
Author(s):  
Ganesh Jayaram
Keyword(s):  
Surface Science ◽  
High Vacuum ◽  
Careful Analysis ◽  
Ultra High Vacuum ◽  
Electron Gun ◽  
Silicon Surfaces ◽  
Diffraction Spot ◽  
Stable Operation ◽  
Thin Sample ◽  
Atomic Structures

Detailed information about the structure of silicon surfaces is very important prior to deposition of metal contacts. Though transmission electron diffraction is sensitive to the atomic structures of both the surface and the bulk, under appropriate conditions, information on the structure of the surface can be obtained from a careful analysis of the diffraction spot intensities.Since Si(100) surface is highly reactive (sticking coefficient for water = 1), preparation and observation of clean surfaces necessitates ultra-high vacuum (UHV) conditions. A thin sample of Si(100) (B doped to 1 ohm-cm) was prepared for observation inside a Hitachi UHV-H9000 300keV electron microscope (stable operation pressure ∼9xl0-11 Torr). It was mechanically polished, dimpled and ion-milled before being transferred into a UHV surface science chamber attached to the microscope. In situ sample preparation carried out inside this chamber involved a combination of sputtering using 2-4 keV argon ions (to clean the surface) and electron-gun annealing cycles (to order the surface).

Microstructures of Si(111) on Ion Sputtering and Electron Annealing

1991 ◽  
Vol 236 ◽  
Author(s):  
R. Al ◽  
T. S. Savage ◽  
P. Xu ◽  
J. P. Zhang ◽  
L. D. Marks
Keyword(s):  
Sample Preparation ◽  
Surface Science ◽  
Microstructure Evolution ◽  
Preparation Method ◽  
Ion Beam ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ion Beam Sputtering ◽  
Transmission Electron ◽  
Beam Sputtering

AbstractThe microstructure evolution during preparation of thin Si(111) samples for surface sensitive imaging has been studied using ultra-high vacuum (UHV) transmission electron microscopy (TEM). The effects of ion beam sputtering and electron annealing have been investigated. A unique and routine sample preparation method for surface sensitive TEM imaging that combines TEM sample preparations with surface science sample preparation was developed. The microstructure evolution during the sample preparation process was studied in detail.

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.

UHV microscopy of surfaces: Recent results

1989 ◽  
Vol 47 ◽  
pp. 550-551
Author(s):  
J.E. Bonevich ◽  
J.P. Zhang ◽  
M. Jacoby ◽  
R. Ai ◽  
D. Dunn ◽  
...  
Keyword(s):  
Surface Science ◽  
Gold Film ◽  
Ion Beam ◽  
High Vacuum ◽  
Auger Spectroscopy ◽  
Ultra High Vacuum ◽  
Ion Beam Sputtering ◽  
Optical Heating ◽  
Beam Sputtering ◽  
Better Than

In order to examine surfaces of materials, a prerequisite is a microscope which combines ultra-high vacuum (UHV) with surface science cleaning and characterization techniques such as ion beam sputtering, annealing, and Auger spectroscopy. In order to achieve this, we have mounted onto the side of a UHV-H9000 microscope LEED/Auger, an ion gun, and optical heating; in the transfer chamber specimens can be cleaned at a base pressure of 2×10-10 torr and transferred into the microscope which operates at pressures better than 2×10-10 torr. With this marriage, it is relatively simple to prepare and characterize clean surfaces.As an example, thin gold film specimens, textured with the [111] normal to the film, were made in a standard vacuum evaporator and floated onto a gold grid. The transfer chamber was then baked-out at 250°C for about 12 hours to achieve UHV conditions. Figure 1 shows an image taken from the gold film after bakeout.

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.

Initial Oxidation Kinetics of Copper (110) Thin Films As Investigated By IN SITU UHV-TEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 1274-1275
Author(s):  
Guang-Wen Zhou ◽  
Mridula D.Bharadwaj ◽  
Judith C.Yang
Keyword(s):  
Surface Science ◽  
Room Temperature ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Science Methods ◽  
Metal Oxidation ◽  
Initial Oxidation ◽  
Transmission Electron ◽  
Kinetics Of

In the study of metal oxidation, there is a wide gap between information provided by surface science methods and that provided by bulk oxidation studies. The former have mostly examined the adsorption of up to ∽1 monolayer (ML) of oxygen on the metal surface, where as both low and high temperature bulk oxidation studies have mainly focused on the growth of an oxide layer at the later stages of oxidation. Hence, we are visualizing the initial oxidation stages of a model metal system by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), where the surfaces are atomically clean, in order to gain new understanding of these ambiguous stages of oxidation. We have previously studied the growth of Cu2O islands during initial oxidation of Cu(100) film. We are presently investigating the initial stages of Cu(110) oxidation, from 10−4 Torr O2 to atmospheric pressures and temperature range from room temperature to 700 °C.

In Situ Uhv-Tem Oxidation And Reduction Of Metals

1999 ◽  
Vol 5 (S2) ◽  
pp. 132-133
Author(s):  
J. C. Yang ◽  
M Yeadon ◽  
B. Kolasa ◽  
J. M. Gibson
Keyword(s):  
Surface Science ◽  
Materials Science ◽  
Film Growth ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Science Methods ◽  
Copper Oxidation ◽  
Transmission Electron ◽  
Partial Pressures

In this proceedings, we present a review of our experimental results of our investigations of the mechanisms of the initial stages of copper oxidation. We examined the initial stages of Cu(001) oxidation and reduction by in situ ultra-high vacuum (UHV) transmission, electron microscopy (TEM). We observed surface reconstruction and nucleation and growth of copper oxide islands. We have examined the oxidation processes from oxygen partial pressures of 10-5 torr to atmospheric pressures and temperatures from 25°C to 600°C, in order to gain fundamental insights into this important gas-metal reaction.Fundamental knowledge of gas-metal reactions, in particular oxidation, is important for a wide variety of materials science fields, such as dry corrosion, catalysis, as well as some thin film growth, such as ferroelectrics. However, there is a wide gap between information provided by surface science methods and that provided by bulk oxidation studies. The former have mostly examined the adsorption of up to ˜1ML of oxygen on the metal surface.

Initial Kinetics of Copper Oxidation in Different Oxidizing Atmospheres as Studied by In Situ UHV-TEM

2000 ◽  
Vol 6 (S2) ◽  
pp. 42-43
Author(s):  
Mridula D. Bharadwaj ◽  
Lori Tropia ◽  
Murray Gibson ◽  
Judith C. Yang
Keyword(s):  
Surface Science ◽  
High Vacuum ◽  
Practical Interest ◽  
Ultra High Vacuum ◽  
Copper Oxidation ◽  
Initial Oxidation ◽  
Kinetics Of Oxidation ◽  
Transmission Electron ◽  
Kinetics Of

It is of fundamental and practical interest to understand the oxidation process since a desirable property for metals is resistance to corrosion. But there is a wide gap between information provided by surface science methods and that provided by bulk oxidation studies. The former have mainly examined the adsorption of ∼ 1 ML of oxygen on the metal surface, where as both low and high temperature bulk oxidation studies have mainly focused on the growth of an oxide layer at the later stages of oxidation.We are probing the initial oxidation stage of a model metal system by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM) in order to gain insights into the initial kinetics of oxidation. We have previously shown that the growth mechanism of the cuprous oxide is initially dominated by oxygen surface diffision.

The structure and basic operating modes of a STEM

1984 ◽  
Vol 42 ◽  
pp. 332-335
Author(s):  
John B. Vander Sande
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Electron Gun ◽  
Vacuum System ◽  
Major Advance ◽  
Operating Modes ◽  
Transmission Electron

The scanning transmission electron microscope (STEM) represents a major advance in the microanalytical capabilities of instruments available to materials scientists. The STEM concept resulted from the desire to combine features of the transmission electron microscope (TEM), scanning electron microscope (SEM), and the electron microprobe. Several types of STEMs are currently in use; they can be divided into roughly three categories based on origin and philosophy of design. First are the “dedicated” STEMs, pioneered by Crewe and his coworkers, which generally use a field-emission electron gun housed in an ultra-high-vacuum system. A conventional TEM may also be equipped with a scanning attachment and an electron detector and/or spectrometer, yielding what may be referred to as a TEM(S). Finally, in practice an SEM may be fitted with a transmission stage; in this case the designation SEM(T) may be most appropriate. The first two designs are by far the most popular for currently available commercial instruments.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

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