A surface science compatible epifluorescence microscope for inspection of samples under ultra high vacuum and cryogenic conditions

2017 ◽  
Vol 88 (8) ◽  
pp. 083702 ◽  
Author(s):  
Christian Marquardt ◽  
Alexander Paulheim ◽  
Nils Rohbohm ◽  
Rudolf Merkel ◽  
Moritz Sokolowski
Author(s):  
Michael T. Marshall ◽  
Xianghong Tong ◽  
J. Murray Gibson

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.


1990 ◽  
Vol 43 (5) ◽  
pp. 583
Author(s):  
GL Price

Recent developments in the growth of semiconductor thin films are reviewed. The emphasis is on growth by molecular beam epitaxy (MBE). Results obtained by reflection high energy electron diffraction (RHEED) are employed to describe the different kinds of growth processes and the types of materials which can be constructed. MBE is routinely capable of heterostructure growth to atomic precision with a wide range of materials including III-V, IV, II-VI semiconductors, metals, ceramics such as high Tc materials and organics. As the growth proceeds in ultra high vacuum, MBE can take advantage of surface science techniques such as Auger, RHEED and SIMS. RHEED is the essential in-situ probe since the final crystal quality is strongly dependent on the surface reconstruction during growth. RHEED can also be used to calibrate the growth rate, monitor growth kinetics, and distinguish between various growth modes. A major new area is lattice mismatched growth where attempts are being made to construct heterostructures between materials of different lattice constants such as GaAs on Si. Also described are the new techniques of migration enhanced epitaxy and tilted superlattice growth. Finally some comments are given On the means of preparing large area, thin samples for analysis by other techniques from MBE grown films using capping, etching and liftoff.


1998 ◽  
Vol 4 (S2) ◽  
pp. 316-317
Author(s):  
D. N. Leonard ◽  
P.E. Russell

Atomic force microscopy (AFM) was introduced in 1984, and proved to be more versatile than scanning tunneling microscopy (STM) due to the AFM's capabilities to scan non-conductive samples under atmospheric conditions and achieve atomic resolution. Ultra high vacuum (UHV) AFM has been used in surface science applications when control of oxidation and corrosion of a sample's surface are required. Expensive equipment and time consuming sample exchanges are two drawbacks of the UHV AFM system that limit its use. Until recently, no hot/cryo-stage, moderate vacuum, controlled gas environment AFM was commonly available.We have demonstrated that phase transformations are easily observable in metal alloys and polymers with the use of a moderate vacuum AFM that has in-situ heating/cooling capabilities and quick (within minutes) sample exchange times. This talk will describe the results of experiments involving a wide range of samples designed to make use of the full capabilities of a hot/cryo-stage, controlled gas environment AFM.


Author(s):  
K.D. van der Mast ◽  
A.J. Koster

In general instrumental developments are caused either by new application demands or by the availability of new technologies. If we investigate the trends in application demands, some predictions can be made safely: More and more the TEM will be used as an analytical instrument. The number of desired signals (detectors) will increase and the quality of the signals must be improved in terms of noise and electron efficiency. Examples are parallel collection EELS and Auger detectors (Kruit and Venables, 1988).The first experiments on coincidence techniques are also promising (Kruit et al, 1984) and exciting new ideas are investigated today. Besides this, another area of applications will probably become more important: surface science in situ experiments. Especially for this type of experiments it is difficult to transfer the specimen to another system without spoiling the experiment. So these applications will lead to an ultra high vacuum specimen environment - constructed in a way that many accessories necessary for surface experiments can be added: Ion guns, preparation chamber, knudsen cells etc.


Author(s):  
P. Xu ◽  
L. D. Marks

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.


Author(s):  
J.E. Bonevich ◽  
J.P. Zhang ◽  
M. Jacoby ◽  
R. Ai ◽  
D. Dunn ◽  
...  

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.


Author(s):  
M.I. Buckett ◽  
S.R. Singh ◽  
H. Fan ◽  
T. Wagner ◽  
L. D. Marks

HREM has recently entered the surface science arena as a complementary technique for studies of electron-stimulated damage of oxide surfaces. The primary advantage offered is the ability to observe in-situ structural changes of the surface, as has been exemplified in the literature for NiO, WO3, V2O5, and TiO2, among other oxide crystals. One major drawback has been the inability to perform experiments under UHV conditions comparable to those used in conventional surface science techniques. Previous HREM reports have not considered the effect of the microscope environment in surface radiation damage.In this study, we compared the surface radiation damage effects of oxides under UHV conditions (l0-10 Torr in a Hitachi UHV-H9000 instrument) to damage effects observed in conventional instruments (operating at approximately 10-7 Torr). A number of oxides were investigated, including NiO, V2O5 , WO3 , MoO3 , TiO2, and Ta2O5. Our results indicate that although the same basic damage mechanisms are operative under both vacuum conditions, subsequent surface alteration due to reoxidation or reaction with surface contamination occurs under non-UHV conditions. WO3, for example, underwent surface-initiated reduction to metallic W under UHV conditions (Fig. 1, 2 ).


Author(s):  
A. von Oertzen ◽  
H.H. Rotermund ◽  
S. Jakubith ◽  
S. Kubala ◽  
G. Ertl

Photoelectron microscopes using electron optics had been built long before. Until recently these microscopes were not widely used in surface science due to unsufficient vacuum conditions as well as weak image intensifying devices. In this paper we will present a new approach to photoelectron microscopy, the Scanning Photoelectron Microscope (SPM).Photoelectron emission will occur as soon as the photon energy is higher than the work function on the illuminated area. Since work functions never exceed 6.5 eV, ultraviolet (UV) light with λ ≥ 190 nm will be appropriate. This kind of radiation is a very gentle probe, even for sensitive adlayers.The experimental setup is shown schematicaly in Fig. 1. A UV light optics outside the ultra high vacuum (UHV) system focusses the actual 30 W Deuterium discharge lamp through a grid monochromator onto a small aperture (50 to 400 microns). The aperture hole is projected with a reflecting microscope objective (Schwarzschild type) onto the surface of the sample yielding a lateral resolution of about 3 microns.


2001 ◽  
Vol 7 (S2) ◽  
pp. 1274-1275
Author(s):  
Guang-Wen Zhou ◽  
Mridula D.Bharadwaj ◽  
Judith C.Yang

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.


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