Electron-beam damage of oxides at high current densities

1989 ◽  
Vol 47 ◽  
pp. 634-635
Author(s):  
M. R. McCartney ◽  
J. K. Weiss ◽  
David J. Smith
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Current Density ◽  
Transition Metal Oxides ◽  
Time Resolved ◽  
Rapid Acquisition ◽  
Resolution Electron ◽  
Current Densities ◽  
Electron Stimulated Desorption ◽  
Channel Analyzer

It is well-known that electron-beam irradiation within the electron microscope can induce a variety of surface reactions. In the particular case of maximally-valent transition-metal oxides (TMO), which are susceptible to electron-stimulated desorption (ESD) of oxygen, it is apparent that the final reduced product depends, amongst other things, upon the ionicity of the original oxide, the energy and current density of the incident electrons, and the residual microscope vacuum. For example, when TMO are irradiated in a high-resolution electron microscope (HREM) at current densities of 5-50 A/cm2, epitaxial layers of the monoxide phase are found. In contrast, when these oxides are exposed to the extreme current density probe of an EM equipped with a field emission gun (FEG), the irradiated area has been reported to develop either holes or regions almost completely depleted of oxygen. ’ In this paper, we describe the responses of three TMO (WO3, V2O5 and TiO2) when irradiated by the focussed probe of a Philips 400ST FEG TEM, also equipped with a Gatan 666 Parallel Electron Energy Loss Spectrometer (P-EELS). The multi-channel analyzer of the spectrometer was modified to take advantage of the extremely rapid acquisition capabilities of the P-EELS to obtain time-resolved spectra of the oxides during the irradiation period. After irradiation, the specimens were immediately removed to a JEM-4000EX HREM for imaging of the damaged regions.

Electron beam induced modifications of SnO2 and SrTiO3

1990 ◽  
Vol 48 (4) ◽  
pp. 800-801
Author(s):  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Transition Metal Oxides ◽  
Damage Mechanism ◽  
Resolution Electron ◽  
Metal Ratio ◽  
High Resolution Electron Microscope ◽  
Current Densities ◽  
Electron Stimulated Desorption

In addition to providing information about the interaction of ionizing radiation with solids, a knowledge of the changes induced in the specimen by the electron beam is important when interpreting high-resolution electron micrographs of surfaces. Beam-induced modifications to the surfaces of several maximally-valent transition-metal oxides (TMO) have been previously reported. It was found that irradiation at 400keV within a high-resolution electron microscope (HREM) caused TiO2, V2O5, Nb2O5, and WO3 to reduce epitaxially to their respective monoxide phases. Because of their ionicity and relatively deep core levels, these materials should be susceptible to electron-stimulated desorption (ESD) of oxygen due to a radiolytic damage mechanism proposed by Knotek and Feibelman (K-F) involving inter-atomic Auger decay of core holes on the metal ions. Reduction of these oxides to the (metallic) monoxide phases within the HREM is consistent with this mechanism. When these oxides were exposed to the extreme current densities available in a 100keV electron microscope equipped with a field emission gun (FEG) they developed pits at the probe position . Electron energy loss spectroscopy (EELS) studies established that they had suffered mass loss and a reduction in the oxygen/metal ratio. HREM imaging occasionally revealed lattice fringes corresponding to the bare metal in the amorphous contrast of these pits.

Time-resolved high-resolution electron microscopy of nanometer-scale electron beam processing of PbTe films

1996 ◽  
Vol 54 ◽  
pp. 980-981
Author(s):  
T. Kizuka ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Room Temperature ◽  
High Resolution Electron Microscopy ◽  
Nanometer Scale ◽  
Time Resolved ◽  
Electron Beam Processing ◽  
Resolution Electron

Various kinds of nanometer scale processings are required to produce advanced materials, for example, nano-structured electric devices. Electron beam processing at nanometer scale using STEM and TEM, such as drilling and line-writing, is recently interested as a most useful method. Details of structural change during the processing should be elucidated at atomic resolution in order to establish the processing. In the present work we have processed lead telluride (PbTe) films with nanometer electron beam in a high-resolution transmission electron microscope and in-situ observed the variation of atomic arrangements during the processing.PbTe of 99.99% was vacuum-deposited on air-cleaved (001) surfaces of sodium chloride at room temperature. Time-resolved high-resolution electron microscopy was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder. The spatial resolution of thesystem was 0.2 nm at 200 kV and the time resolution was 1/60 s. Electron beam irradiation density was 120 A/cm2 at the processing and the observation.

Aluminosilicate diagenesis in a Tertiary sandstone-mudrock sequence from the central North Sea, UK

Clay Minerals ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 523-536 ◽  
Author(s):  
J. M. Huggett
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Mass Balance ◽  
North Sea ◽  
Chemical Interaction ◽  
Point Counting ◽  
Resolution Electron ◽  
Tertiary Sandstone ◽  
Central North Sea

AbstractMudrocks and sandstones from the Palaeocene of the central North Sea have been studied to assess the petrology, diagenesis and extent of any chemical interaction between the two lithologies. Authigenic and detrital minerals have been distinguished using a variety of electron microscope techniques. Small but significant quantities of authigenic minerals, which would not be detected by conventional petrographic tools, have been detected through the use of high-resolution electron beam techniques. Sandstone mineralogy has been quantified by point counting, and mudrock mineralogy semi-quantified by XRD. The detrital and authigenic mineralogy in the sandstone is almost identical to that found in the mudrock. The principal difference is in the relative proportions. Qualitative mass balance suggests that cross-formational flow has not been significant in either clay or quartz diagenesis.

Epitaxial Relationships in Esd Processes on Oxide Surfaces

1988 ◽  
Vol 129 ◽  
Author(s):  
M.R. Mccartney ◽  
David J. Smith
Keyword(s):  
Electron Microscope ◽  
Transition Metal ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Structural Features ◽  
Epitaxial Relationship ◽  
Crystalline Layer ◽  
Electron Stimulated Desorption ◽  
Intense Electron

ABSTRACTDuring intense electron irradiation inside the electron microscope, the electron—stimulated desorption of oxygen from the surfaces of several maximally—valent transition—metal oxides (TiO2, V2O5, Nb2 O5 and WO3) has been observed [1]. The irradiatedsurfaces become covered with a crystalline layer of the corresponding monoxide phase. These reduced phases, which are all based on cubic structures and have metallic conductivity, grow with a well— defined epitaxial relationship with the bulk oxide. Computer—drawn models of the crystal structures have been used to study the atomic arrangements implied by the epitaxial relationship, and certain structural features were found to be common to the oxides studied.

scholarly journals A STUDY OF MASS LOSS AND PRODUCT FORMATION AFTER IRRADIATION OF SOME DRY AMINO ACIDS, PEPTIDES, POLYPEPTIDES AND PROTEINS WITH AN ELECTRON BEAM OF LOW CURRENT DENSITY

1970 ◽  
Vol 18 (8) ◽  
pp. 574-580 ◽  
Author(s):  
K. S. STENN ◽  
G. F. BAHR
Keyword(s):  
Amino Acids ◽  
Electron Beam ◽  
Electron Microscope ◽  
Steady State ◽  
Mass Loss ◽  
Current Density ◽  
Product Formation ◽  
Electron Microscopic ◽  
Microscopic Specimen ◽  
Loss Of Mass

Amino acids, peptides, polypeptides and proteins were irradiated with electrons at 70-kv accelerating potential in an electron microscope mockup. Loss of mass and chemical changes occur almost instantaneously. For a given dose rate an organic object is converted to a steady state product. This is characterized by a poorly structured infrared pattern, unchanging elemental composition. The higher the polymerization of the target the smaller was the effect of the irradiation. Such studies conducted outside of the electron microscope reveal only qualitatively what might occur to the electron microscopic specimen during observation.

Identification of T1 phase in Al-Li-Cu alloy (2090)

1992 ◽  
Vol 50 (1) ◽  
pp. 188-189
Author(s):  
J.S. Kim ◽  
S. S. Baek ◽  
G. H. Kim ◽  
C. H. Chun
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Zone Axis ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cu Alloy ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
Optical Laser

In Al-Li-Cu alloy(2090) the extra spots in the Selected Area Diffraction Pattern (SADP) of [112]α zone axis have been argued. Huang and Ardell described that the extra spots were originated from T1 variants tilted to electron beam. Rioja and Ludwiczak, however, presented that die precursor of T1 termed T1' was present in alloy(2090) and generated the extra spots. Rioja and Ludwiczak explained die existence of extra spots as making the simulated SADP diagrams and analyzing x ray diffraction lines of T1'. The existence of T1' has been inconsistent with the other papers. Huang and Ardell's model has been well recognized in present. The investigations on the extra spots had mainly been restricted in [112]α SADP. In the present paper, the extra spots from [110]αand [100]α zone axes were investigated using High Resolution Electron Microscope (HREM) and optical laser diffractometer.

Ultra-high resolution electron-beam lithography with a research scanning electron microscope

1983 ◽  
Vol 41 ◽  
pp. 102-103
Author(s):  
H. G. Craighead
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Electron Beam Lithography ◽  
Pattern Generation ◽  
Resolution Limit ◽  
Sensitive Material ◽  
Probe Size ◽  
Resolution Electron ◽  
Electron Detection ◽  
Backscattered Electron

An electron microscope of the type normally used for analysis has been employed as an experimental beam writing instrument. With this instrument less than 10 nm size structures have been fabricated in a variety of materials by electron beam lithography. The important parameters that determine the resolution limit are: electron beam probe size, electron beam energy, characteristics of the beam sensitive material and the nature of the substrate. These parameters were studied with a Philips 400 T TEM/STEM/SEM modified for external beam control and interfaced to a DEC MINC 11-23 computer for pattern generation. With this microscope's ability to image thick samples by secondary and backscattered electron detection conventional type lithography was done on semiconductor substrates. The general lithographic technique is described, for example, in reference 2. In addition fabrication techniques on thin films were studied. The effect of the resolution determining parameters and several examples of lithographic results are described in this paper.

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