The Influence of Diamond Surface Perfection on the Preferential Nucleation of SP2 Carbon During Methane Pyrolysis

1992 ◽  
Vol 280 ◽  
Author(s):  
B. Y. Lin ◽  
C. P. Beetz ◽  
D. W. Brown ◽  
B. A. Lincoln
Keyword(s):  
Natural Diamond ◽  
High Energy ◽  
Diamond Surface ◽  
Structural Defects ◽  
High Energy Electron ◽  
Diamond Surfaces ◽  
Preferential Nucleation ◽  
Cvd Diamond Film ◽  
Surface Morphologies ◽  
Methane Pyrolysis

ABSTRACTWe report a set of CH4 pyrolysis experiments in a UHV system on diamond surfaces having varying degrees of surface roughness or perfection. Scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and reflection high energy electron diffraction (RHEED) were used to examine the formation of graphite and the resulting surface morphologies. A (100) type Ha natural diamond having 3 sputtered craters on the surface was used as the substrate, sp2 carbon was formed preferentially on the structurally defective crater surfaces after ∼3×1010 L of CH4 exposure at 900°C, whereas essentially no sp2 carbon was found on the flat portions of the diamond surface. Similar experiments were also carried out on a polycrystalline CVD diamond film and sp2 carbon was formed on that surface afte ∼4×109 L of CH4 exposure at 900°C. These results indicate that structural defects on diamond surfaces are a crucial factor in the preferential nucleation of sp2 carbon during CH4 pyrolysis.

Evolution of surface morphology during epitaxial growth

1993 ◽  
Vol 344 (1673) ◽  
pp. 493-505 ◽  
Keyword(s):  
Epitaxial Growth ◽  
Large Scale ◽  
High Energy ◽  
Atomic Scale ◽  
High Energy Electron ◽  
Vicinal Surfaces ◽  
Basic Model ◽  
Surface Steps ◽  
Simulated Surface ◽  
Surface Morphologies

We examine the type of information that can be obtained from Monte Carlo simulations of epitaxial growth. A basic model will be first introduced and some of the features that make it suitable for describing both atomic-scale processes and large-scale morphologies will be pointed out. The ability of this model to reproduce experimental data will then be addressed. The first example discussed will be growth on GaAs(OO1) vicinal surfaces, where the density of surface steps on the simulated surfaces reproduces quantitatively the evolution of the reflection high-energy electron diffraction (RHEED) intensity oscillations for appropriately chosen growth and diffraction conditions. This work will then be used as a basis for examining the predictions of the simulated surface morphologies on patterned substrates, based on comparisons with micro-RHEED measurements. Extensions of the basic model to more complex growth scenarios where the atomic constituents are delivered in the form of heteroatomic molecules will also be discussed.

Secondary Electron Emission Spectroscopy of Crystalline and Non-Crystalline Carbon Allotropes

1990 ◽  
Vol 201 ◽  
Author(s):  
Alon Hoffman ◽  
Steven Prawer
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Ion Irradiation ◽  
Quartz Substrate ◽  
Natural Diamond ◽  
Pyrolytic Graphite ◽  
Secondary Electron Emission ◽  
Diamond Surface ◽  
Diamond Surfaces ◽  
Diamond Thin Film

AbstractThe Secondary Electron Emission (SEE) spectra of type Ha diamond, highly oriented pyrolytic graphite (HOPG), amorphous carbon (e-beam evaporated), glassy carbon and amorphic-diamond (filtered arc evaporated) were measured in the 0–80 eV electron kinetic energy range, and found to be very distinctive for the different carbon allotropcs. The sensitivity of SEE spectroscopy to crystal damage for the type Ha diamond surface was studied by performing SEE measurements as function of 1 keV argon ion irradiation dose. Two examples of the use of SEE in the characterization of diamond surfaces are presented. In the first, the crystalline quality of the back and front surfaces of a chemically vapour deposited diamond thin film which had dclaminated from a fused quartz substrate were compared using SEE and, in the second, SEE was used to provide a qualitative estimate of the damage induced by mechanical polishing of a natural diamond surface.

The Effect of High Energy Electron Beam on the Interaction Between CH4/CF4 and the Diamond (100) Surface

1992 ◽  
Vol 279 ◽  
Author(s):  
B. Y. Lin ◽  
C. P. Beetz ◽  
D. W. Brown ◽  
B. A. Lincoln
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Auger Spectroscopy ◽  
High Energy ◽  
Energy Electron ◽  
Diamond Surface ◽  
High Energy Electron ◽  
Gas Exposure

ABSTRACTThe interaction of the diamond (100) surface with pure CH4 and CF4 gases was investigated as a function of temperature and total gas exposure. We found that sp2 carbon does not form on the diamond (100) surface after exposures of up to lO9L of CH4 or 106 L of CF4 in a UHV system over the range of temperatures from room temperature to 900°C. When a high energy electron beam (5keV) intersected the path of the impinging gas or the diamond surface was exposed to a high energy electron beam before gas exposures, sp2 carbon was not produced at levels detectable by Auger spectroscopy. However, sp2 carbon was formed when the gas exposure was coincident with the electron beam on the diamond surface. The mechanisms responsible for these observations are discussed.

A Stationary Solution of High-Energy Electron Reflection (HEER) for An Arbitrary Surface

1990 ◽  
Vol 48 (2) ◽  
pp. 374-375
Author(s):  
YIQUN MA
Keyword(s):  
Stationary Solution ◽  
High Energy ◽  
Bloch Wave ◽  
Dynamical Theory ◽  
High Energy Electron ◽  
Bulk Materials ◽  
Periodic Surface ◽  
Electron Transmission ◽  
Electron Reflection ◽  
Long Time

For a long time, the development of dynamical theory for HEER has been stagnated for several reasons. Although the Bloch wave method is powerful for the understanding of physical insights of electron diffraction, particularly electron transmission diffraction, it is not readily available for the simulation of various surface imperfection in electron reflection diffraction since it is basically a method for bulk materials and perfect surface. When the multislice method due to Cowley & Moodie is used for electron reflection, the “edge effects” stand firmly in the way of reaching a stationary solution for HEER. The multislice method due to Maksym & Beeby is valid only for an 2-D periodic surface.Now, a method for solving stationary solution of HEER for an arbitrary surface is available, which is called the Edge Patching method in Multislice-Only mode (the EPMO method). The analytical basis for this method can be attributed to two important characters of HEER: 1) 2-D dependence of the wave fields and 2) the Picard iteractionlike character of multislice calculation due to Cowley and Moodie in the Bragg case.

Parabolas from Reconstructed Surfaces Observed in Convergent-Beam RHEED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 398-399
Author(s):  
M. Gajdardziska-Josifovska
Keyword(s):  
Electron Microscopy ◽  
High Energy ◽  
Two Dimensional ◽  
High Energy Electron ◽  
Reflection And Transmission ◽  
Experimental Diffraction Pattern ◽  
Surface Resonance ◽  
Reconstructed Surfaces ◽  
Reflection Electron Microscopy ◽  
Convergent Beam

Parabolas have been observed in the reflection high-energy electron diffraction (RHEED) patterns from surfaces of single crystals since the early thirties. In the last decade there has been a revival of attempts to elucidate the origin of these surface parabolas. The renewed interest stems from the need to understand the connection between the parabolas and the surface resonance (channeling) condition, the latter being routinely used to obtain higher intensity in reflection electron microscopy (REM) images of surfaces. Several rather diverging descriptions have been proposed to explain the parabolas in the reflection and transmission Kikuchi patterns. Recently we have developed an unifying general treatment in which the parabolas are shown to be K-lines of two-dimensional lattices. Here we want to review the main features of this description and present an experimental diffraction pattern from a 30° MgO (111) surface which displays parabolas that can be attributed to the surface reconstruction.

Kinematic Approximations in TED and RHEED Analysis of Reconstructed Surfaces

1990 ◽  
Vol 48 (2) ◽  
pp. 396-397
Author(s):  
L. -M. Peng ◽  
M. J. Whelan
Keyword(s):  
Electron Diffraction ◽  
Kinematic Analysis ◽  
Incident Beam ◽  
High Energy ◽  
Energy Electron ◽  
Great Success ◽  
High Energy Electron ◽  
Kinematic Approximation ◽  
Reconstructed Surfaces

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.

Reflection electron microscopy of as-grown diamond surfaces

1993 ◽  
Vol 51 ◽  
pp. 1006-1007
Author(s):  
Z.L. Wang ◽  
J. Bentley ◽  
R.E. Clausing ◽  
L. Heatherly ◽  
L.L. Horton
Keyword(s):  
Electron Microscopy ◽  
Synthetic Diamond ◽  
High Energy ◽  
Dark Field ◽  
Reverse Direction ◽  
Diamond Surfaces ◽  
Grain Sizes ◽  
Synthetic Diamonds ◽  
De Beers ◽  
Reflection Electron Microscopy

It has been found that the abrasion of diamond-on-diamond depends on the crystal orientation. For a {100} face, the friction coefficient for sliding along <011> is much higher than that along <001>. For a {111} face, the abrasion along <11> is different from that in the reverse direction <>. To interpret these effects, a microcleavage mechanism was proposed in which the {100} and {111} surfaces were assumed to be composed of square-based pyramids and trigonal protrusions, respectively. Reflection electron microscopy (REM) has been applied to image the microstructures of these diamond surfaces.{111} surfaces of synthetic diamond:The synthetic diamonds used in this study were obtained from the De Beers Company. They are in the as-grown condition with grain sizes of 0.5-1 mm without chemical treatment or mechanical polishing. By selecting a strong reflected beam in the reflection high-energy electron diffraction (RHEED) pattern, the dark-field REM image of the surface is formed (Fig. 1).

Ion Beam Imaging Methodology of Invisible Metal under Insulator Using High Energy Electron Beam Charging

2007 ◽  
Author(s):  
C.H. Wang ◽  
S.P. Chang ◽  
C.F. Chang ◽  
J.Y. Chiou
Keyword(s):  
Metal Ion ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Electrical Measurement ◽  
High Energy ◽  
Advanced Technology ◽  
High Energy Electron ◽  
Common Assumption ◽  
Dual Beam ◽  
Imaging Methodology

Abstract Focused ion beam (FIB) is a popular tool for physical failure analysis (FA), especially for circuit repair. FIB is especially useful on advanced technology where the FIB is used to modify the circuit for new layout verification or electrical measurement. The samples are prepared till inter-metal dielectric (IMD), then a hole is dug or a metal is deposited or oxide is deposited by FIB. A common assumption is made that metal under oxide can not be seen by FIB. But a metal ion image is desired for further action. Dual beam, FIB and Scanning Electron Microscope (SEM), tools have a special advantage. When switching back and forth from SEM to FIB the observation has been made that the metal lines can be imaged. The details of this technique will be discussed below.

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