Preparation of Planar and Cross-Sectional Thin Specimens by Chemical Dimpling with Optically Controlled Terminator

1990 ◽  
Vol 199 ◽  
Author(s):  
D. M. Hwang ◽  
L. Nazar ◽  
C. Y. Chen
Keyword(s):  
High Resolution ◽  
Compound Semiconductor ◽  
Chemical Polishing ◽  
Semiconductor Materials ◽  
Ion Milling ◽  
Lattice Imaging ◽  
Cross Sectional

ABSTRACTWe have modified a conventional dimpling machine to perform chemical polishing with a reactive etchant. The modified dimpler also detects specimen perforation in situ optically, and automatically stops the dimpling process by lifting the dimpler wheel and flooding the specimen with a rinse solution. Using this apparatus, we are able to prepare both planar and cross-sectional thin specimens of compound semiconductor materials without using expensive and time-consuming ion-milling. The specimens have large thin areas, are free of artifacts, and are suitable for high-resolution lattice imaging.

Cross-Sectional Sample Preparation and Analysis of Intergranular Stress Corrosion Cracks in FE-NI-CR Alloys.

1999 ◽  
Vol 5 (S2) ◽  
pp. 884-885
Author(s):  
L.E. Thomas ◽  
S.M. Bruemmer
Keyword(s):  
High Resolution ◽  
Stress Corrosion ◽  
Crack Opening ◽  
Analytical Form ◽  
Ion Milling ◽  
Intergranular Stress Corrosion ◽  
Cross Sectional ◽  
Preparation Methods ◽  
High Resolution Tem ◽  
Intergranular Stress Corrosion Cracking

Transmission electron microscopy in its modern high-resolution analytical form has great potential for elucidating mechanisms of environmental cracking in structural alloys and other materials. Apart from a few pioneering efforts, the difficulties of preparing suitable samples with the original corrosion structures preserved in narrow crack tips have limited contributions of TEM in this area. Recent work involving cross-sectional crack preparation has focused on intergranular stress-corrosion cracking of Fe- and Ni-base stainless alloys in high-temperature water. This presentation will illustrate preparation methods that have proven successful, and describe limitations of the analysis.The method for preparing cross-section samples suitable for high-resolution TEM characterization is based on earlier work by Lewis et al. It involves preparing a thin section containing cracks filled with epoxy, dimple grinding selected locations near the crack tip, and ion milling. Figure 1 schematically illustrates this method. The first step is to preserve the crack opening characteristics present under loading and protect the crack surfaces during thinning.

The study of compound semiconductor heterostructures by High-resolution transmission electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 842-843
Author(s):  
A.G. Cullis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Chemical Vapour ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Compound Semiconductor ◽  
Organic Chemical ◽  
Cross Sectional ◽  
Transmission Electron

Heteroepitaxial compound semiconductor systems have increasing importance for the fabrication of advanced electronic devices. Microstructural characterisation of the finest features of these materials can be carried out using transmission electron microscopy (TEM) and this paper demonstrates the use of high resolution work for heterointerface and related investigations in two different areas.The epitaxial growth of wide band gap II-VI compounds offers potential for a number of optoelectronic device applications. Indeed, in some cases, such as for CdS, it is possible to prepare very high quality Wurtzite-structure layers on Sphalerite substrates, despite the presence of substantial misfit. When hexagonal close-packed CdS is grown by metal-organic chemical vapour deposition on (111)A GaAs, the layer is oriented with (0001)cds //(111)GaAs and [110]cds//[10]GaAs. A cross-sectional, high resolution micrograph of the interface is shown in Fig. 1a where the different atomic stacking in the CdS (ABAB....) and GaAs (ABCABC....) regions is evident.

HREM of epitaxially grown Fe/TiO2 and Cu/TiO2 interfaces

1993 ◽  
Vol 51 ◽  
pp. 834-835
Author(s):  
P. Lu ◽  
F. Cosandey
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Select Area Diffraction ◽  
Ion Milling ◽  
Cross Sectional ◽  
Oxide Interfaces ◽  
Atomic Structures ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
Standard Techniques

High-resolution electron microscopy (HREM) has been used to provide information on atomic structures of metal/oxide interfaces, which are of both scientific and technological interest. In this report, we present results of a study on Fe/TiO2 and Cu/TiO2 interfaces by HREM. The Fe/TiO2 and Cu/TiO2 interfaces were formed by vapor deposition of Fe and Cu on TiO2 (110) surface, respectively, in a UHV chamber with a base pressure of ∽1x10−10 torr. Cross sectional HREM specimens were prepared using standard techniques involving mechanical polishing, dimpling and ion-milling. The samples were examined in an Topcon-002B high-resolution electron microscope. HREM simulations were performed using the EMS program.Figs, 1a and 1b show a HREM micrograph and a select area diffraction pattern of Fe/TiO2 interface, respectively, taken along the TiO2 [001] direction. From Fig.la and Fig.1b, the following orientation relationship is obtained: [001]Fe//[001]TiO2 and (100)Fe//(110)TiO2. With this orientation, there is about 12.6% lattice misfitt along the TiO2 [10] direction.

Reconstructions and Dynamic Processes on CdTe Surfaces Studied by UHV High-Resolution Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 310-311
Author(s):  
Ping Lu ◽  
David J. Smith
Keyword(s):  
High Resolution ◽  
High Vacuum ◽  
Surface Profile ◽  
Ultra High Vacuum ◽  
Ion Milling ◽  
Atomic Displacements ◽  
Main Challenge ◽  
Resolution Electron ◽  
Surface Reconstructions

Surface profile imaging at resolutions of better than 2Å is highly suitable for studies of surface structures and reactions. In the case of semiconductor materials, the main challenge is to prepare surfaces free of any contamination. The technique has previously been used to study surface reconstructions of Si and CdTe. In our previous observations, clean surfaces of CdTe were obtained by careful control of the incident electron beam within a JEM-4000EX high resolution electron microscope with a pressure of 10-7 torr. In the present study, observations of reconstructions and dynamic phenomena on CdTe surfaces were carried out with a Phillips-430ST, modified for Ultra-High Vacuum in the vicinity of the specimen and equipped with an in situ heating facility. The base vacuum in the region of the sample could usually reach ∼3×l0-9 torr after baking the microscope column at ∼120°C for 36 hours. The CdTe specimen was prepared by cutting a large single crystal into 3mm discs in a [110] direction, then mechanically polishing to a thickness of ∼20 microns, and finally ion milling to perforation.When viewed along a [110] projection, the CdTe sample was found to be dominated by clean or nearly clean (111) and (110) surfaces(with amorphous materials less than 5Å) whilst the (001) surface was usually very short and rough. A completely clean surface was obtained by in situ annealing of the crystal to about 200°. The (110) surface was then found to be reconstructed with a very characteristic chevron appearance in the manner described previously. Long and flat CdTe(OOl) surfaces were obtained by insitu annealing of the crystal at ∼510°C at which temperature edges of the crystal started to gradually sublime. Characterization of the surface structure was then possible when the crystal was cooled back down to temperatures below about 300°C. It was found that the (001) surface had a (2×1) reconstruction at temperatures below about 200°C which transformed reversibly into a (3×1) reconstruction over the approximate temperature range of 200°C<T<300°C. Figures la and lb show the (2×1) and (3×1) reconstructed (001) surfaces, viewed along the [110] projection, which were recorded at temperatures of 140°C and 240°C respectively. Structural models for the (2×1) and (3×1) reconstructions, obtained directly on the basis of the experimental images, are shown in Figs.2a and 2b respectively. The (2×1) reconstruction involves a 1/2 monolayer of Cd vacancies and a very large inward contraction of the remaining Cd surface atoms, which then displace the second layer of Te atoms as indicated. This model is similar to that proposed by Chadi for the Ga-rich (2×1) reconstructed GaAs(100) surface. The (3×1) reconstruction involves both the formation of surface dimers and the presence of vacancies at the surface. Every third atomic-pair is missing along the [1,-1,0] direction, and the remaining two atom pairs at the surface form the surface dimer. Although the (3×1) reconstruction has a larger number of electrons in dangling bonds, a surface with vacancies can be relaxed to reduce the strain energy due to the surface dimers. The directions of the atomic displacements away from the ideal dimer positions are indicated in the figure. Relatively large atomic displacements for several layers into the bulk are clearly visible in experimental images, as seen in Fig.lb. Further details of the surface reconstructions can be found elsewhere.

Focused Ion Beam Sample Preparation of Non-Semiconductor Materials

1997 ◽  
Vol 480 ◽  
Author(s):  
M. W. Phaneuf ◽  
N. Rowlands ◽  
G. J. C. Carpenter ◽  
G. Sundaram
Keyword(s):  
Cross Sections ◽  
Automobile Industry ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Semiconductor Industry ◽  
Semiconductor Materials ◽  
Specimen Preparation ◽  
Ion Milling ◽  
Cross Sectional ◽  
Galvannealed Steel

AbstractFocused Ion Beam (FIB) systems have been steadily gaining acceptance as specimen preparation tools in the semiconductor industry. This is largely due to the fact that such instruments are relatively commonplace as failure analysis tools in semiconductor houses, and are commonly used in the preparation of cross-sections for imaging under the ion beam or using an electron beam in an SEM. Additionally, the ease with which cross-sectional TEM specimens of semiconductor devices can be prepared using FIB systems has been well demonstrated. However, this technology is largely unknown outside the semiconductor industry. Relatively few references exist in the literature on the preparation of cross-sectional TEM specimens of non-semiconductor materials by FIB. This paper discusses a specific use of FIB technology in the preparation of cross-sectional TEM specimens of non-semiconductor samples that are difficult to prepare by conventional means. One example of such materials is commercial galvannealed steel sheet that is used to form corrosion resistant auto-bodies for the automobile industry. Cross-sectional TEM specimens of this material have proved difficult and time-intensive to prepare by standard polishing and ion milling techniques due to galvanneal's inherent flaking and powdering difficulties, as well as the different sputtering rates of the various Fe-Zn intermetallic phases present in the galvannealed coatings. TEM results from cross-sectional samples of commercial galvannealed steel coatings prepared by conventional ion milling and FIB techniques are compared to assess image quality, the size of the electron-transparent thin regions that can be readily prepared and the quality of samples produced by both techniques. Specimen preparation times for both techniques are reported.

Microstructure of In-Situ Grown YBa2Cu4O8 Thin Films Deposited by MOCVD

1992 ◽  
Vol 275 ◽  
Author(s):  
K. Uehara ◽  
H. Sakai ◽  
H. Hayashi ◽  
Y. Shiohara ◽  
S. Tanaka
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Substrate Surface ◽  
Film Surface ◽  
Superconducting Thin Films ◽  
Cross Sectional ◽  
Transmission Electron

ABSTRACTHigh-resolution transmission electron microscopy (HREM) has been used to study the microstructures of Y-Ba-Cu-0 superconducting thin films in which the YBa2Cu4O8 phase was the main phase. From cross-sectional observations, the c-normal 123 phase predominated in the film near the substrate surface, while the c-normal 124 phase occupied the region near the film surface. Another remarkable microstructure was that a-normal 123 variants overcame the c-normal 123 region, but the c-normal 124 phase surpassed the a-normal 123 phase in the upper part of the film.

In-situ process for AlGaAs compound semiconductor: Materials science and device fabrication

1994 ◽  
Vol 23 (7) ◽  
pp. 625-634 ◽  
Author(s):  
M. Hong ◽  
K. D. Choquette ◽  
J. P. Mannaerts ◽  
L. H. Grober ◽  
R. S. Freund ◽  
...  
Keyword(s):  
Materials Science ◽  
Compound Semiconductor ◽  
Device Fabrication ◽  
Semiconductor Materials

Cross-sectional time-resolved high-resolution electron microscopy of epitaxial growth of Au on MgO

1996 ◽  
Vol 54 ◽  
pp. 982-983
Author(s):  
T. Kizuka ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Epitaxial Growth ◽  
High Resolution Electron Microscopy ◽  
Vacuum Deposition ◽  
Cross Sectional ◽  
Time Resolved ◽  
Plan View ◽  
Resolution Electron

Vapor phase epitaxial growth techniques are indispensable for production of thin film electric devices. Various structural analyses have been attempted to evaluate the epitaxial growth. Conventional transmission electron microscopy (CTEM) is a most useful method. In particular, it is known that a plan-view time-resolved CTEM of in-situ vacuum-deposition in a microscope can analyze each process of epitaxial growth. The nucleation in vacuum-deposition was also in-situ observed by a time-resolved high resolution electron microscopy (TRHREM). However many unresolved problems still remain in the studies of the epitaxial growth because it is difficult to observe the epitaxial interfaces less than a few nanometer under appropriate conditions. Much more advanced techniques are required for electron microscopy to obtain detailed information.In the present study, a TRHREM for the cross-sectional observation was developed to elucidate the epitaxial growth process in vacuum-deposition.Gold (Au) was vacuum-deposited on (001) surfaces of the magnesium oxide (MgO) substrates at room temperature in a specimen chamber of a 200-kV high-resolution electron microscope (JEOL, JEM2010).

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

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