Electronic Structure and Bonding at Interfaces Between cvd Diamond and Silicon

1994 ◽  
Vol 332 ◽  
Author(s):  
David A. Muller ◽  
Yujiun Tzou ◽  
Rishi Raj ◽  
John Silcox
Keyword(s):  
Cvd Diamond ◽  
Carbon Films ◽  
Interfacial Structure ◽  
Energy Losses ◽  
Defect States ◽  
Diamond Nucleation ◽  
Spatially Resolved ◽  
Probe Size ◽  
Core Excitations ◽  
Electron Energy Loss

ABSTRACTThe interfacial structure of CVD diamond grown on silicon was studied using spatially resolved electron energy loss spectroscopy (EELS) in a UHV STEM with a subnanometer probe size. Both the plasmon and core excitations in the bulk appear to be localized on this scale. Spatial maps of the different bonding configurations of carbon were obtained by forming images from transmitted electrons that had undergone energy losses characteristic of threefold and fourfold coordinated carbon. Films grown on both prescratched silicon and intermediate amorphous carbon layers were examined. In the latter case, diamond nucleation on a narrow sp2 a-C occurred. For diamond grown directly on silicon, at some regions of the interface, threefold coordinated defect states smaller than 1 nm are observed on the diamond side of the interface while at other regions along the interface the presence of an intermediate 2nm thick SiC layer preserves the fourfold coordination of the carbon.

Effects of Fast Secondary Electrons on Spatiallyresolved Low-Loss Eels of Polystyrene

1998 ◽  
Vol 4 (S2) ◽  
pp. 804-805
Author(s):  
K. Siangchaew ◽  
M. Libera
Keyword(s):  
Electron Irradiation ◽  
Phenyl Ring ◽  
Cross Link ◽  
Low Loss ◽  
Secondary Electrons ◽  
Positive Photoresist ◽  
Spatially Resolved ◽  
Probe Size ◽  
Spectroscopic Information ◽  
Electron Energy Loss

A good understanding of the effect of electron irradiation on polymers is necessary in order to optimally utilize the spectroscopic information and resolution of spatially-resolved electron energy-loss spectroscopy (EELS). This investigation studies the effect of electron irradiation on the low-loss spectroscopic signal and spatial resolution obtainable from polystyrene (PS) homopolymer. Because of the conjugated valence electron distribution associated with its pendant phenyl ring, polystyrene is relatively stable under electron irradiation and has well characterized spectroscopic fingerprints including a notable π—π* transition circa 7eV (1). In addition, polystyrene is used as a positive photoresist because it can cross-link effectively when exposed to an electron irradiation (2).The critical dose characterizing degradation of aromatic polymers is of the order 1-10 C/cm2 (3). In practice, the dose delivered to a specimen is determined both by electron probe size and probe current.

Nanoscale Modification Of Amorphous Diamond-Like Carbon Film Surfaces

1995 ◽  
Vol 416 ◽  
Author(s):  
T. W. Mercer ◽  
N. J. Dinardo ◽  
J. P. Sullivan ◽  
T. A. Friedmann ◽  
M. P. Siegal ◽  
...  
Keyword(s):  
Carbon Film ◽  
Carbon Films ◽  
Scanning Tunneling ◽  
Plasmon Energy ◽  
Electron Dose ◽  
Force Microscopy ◽  
Spatially Resolved ◽  
Atomic Force ◽  
Potential Applications ◽  
Electron Energy Loss

ABSTRACTScanning Tunneling and Atomic Force Microscopy (STM, AFM) of amorphous tetrahedral carbon films (a-tC) film surfaces grown by pulsed laser deposition indicate extreme flatness and uniform electronic properties.1 This is consistent with the observed predominance of sp3 (diamond-like) bonding in these materials.2 Potential applications of a-tC films may be enhanced with the ability to modify their surfaces on the nanoscale. Exploiting the metastable nature of the sp3 hybridized state of carbon, the high flux electron beam from an STM tip was used to modify ˜100 nm regions; processing in air or in vacuum produces similar results. STM and AFM maps of the modified regions indicate stable morphologic and electronic structures consistent with a local transformation to sp2 (graphitic) hybridization. Surface potentiometric mapping of these regions indicates a correlation between electron dose and a lowering of the surface potential. In addition, spatially-resolved electron energy loss spectroscopy of the modified areas performed with a Scanning Auger Microscope shows plasmon energy shifts that confirm an elevated sp2 content in the modified regions.3

Atomic Resolution Electronic Structure Using Spatially Resolved Electron Energy Loss Spectroscopy

1994 ◽  
Vol 332 ◽  
Author(s):  
P.E. Batson
Keyword(s):  
Electronic Structure ◽  
High Energy ◽  
Dark Field ◽  
Atomic Resolution ◽  
Small Areas ◽  
Spatially Resolved ◽  
Spectral Interpretation ◽  
Core Excitations ◽  
Z Contrast ◽  
Electron Energy Loss

ABSTRACTElectronic structure in small areas is obtainable by inspection of near edge fine structure of core excitations. We can accomplish this today with near atomic resolution, using EELS at high energy. At IBM, we have obtained results using a sub-0.2nm probe at 120KeV with enough current to allow 200meV resolution studies at the Si L2,3 edge. It is especially crucial for Si-based structures that this allows us to obtain Z-contrast dark field images of the Si lattice at an acceleration voltage that is low enough to minimize radiation damage, but with a high enough current to allow good quality spectra to be obtained. A review of instrumental requirements, spectral interpretation, and applications to Si-Ge alloys is presented.

A Study of the Electronic Structure Near Individual Dislocations in Diamond by Energy-Loss Spectroscopy

1989 ◽  
Vol 162 ◽  
Author(s):  
J. Bruley ◽  
P. E. Batson
Keyword(s):  
Energy Loss ◽  
Local Density ◽  
Threshold Energy ◽  
Defect States ◽  
Surface Layers ◽  
Edge Structure ◽  
Spatially Resolved ◽  
The Difference ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

ABSTRACTSpatially resolved electron energy-loss spectra recorded from very small volumes of diamond containing individual dislocations show extra intensity within the band-gap just below the 1s to bulk conduction band threshold energy, when compared to spectra recorded from neighboring defect free regions. This is interpreted as direct evidence for the presence of vacant defect states associated with the dislocation structure. The contribution of the π* states from the surface layers to this region of the spectra is completely removed by calculating the difference between the spectra recorded on and off the defect. A comparison is drawn between the measured near edge structure and calculations of local density of states reported in the literature.

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

Direct, spatially resolved observation of defect states with electromigration and degradation of single crystal SrTiO3

2020 ◽  
Vol 127 (9) ◽  
pp. 094105 ◽  
Author(s):  
Hantian Gao ◽  
Sulata Sahu ◽  
Clive A. Randall ◽  
Leonard J. Brillson
Keyword(s):  
Single Crystal ◽  
Defect States ◽  
Spatially Resolved

Thin Film Carbon Layers with Continously Changing Bonding Properties

2007 ◽  
Vol 537-538 ◽  
pp. 207-214
Author(s):  
Gergely Kovách ◽  
Gábor Pető ◽  
Albert Karacs ◽  
M. Veres ◽  
Hajnalka Csorbai ◽  
...  
Keyword(s):  
Lower Energy ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Ion Bombardment ◽  
Peak Position ◽  
Carbon Films ◽  
Laser Deposition ◽  
Energy Part ◽  
Bonding Properties ◽  
Electron Energy Loss

Polycrystalline diamond and diamond-like carbon (DLC) films were deposited by microwave chemical vapor deposition (MW-CVD) and by pulsed laser deposition (PLD) respectively. Ar ion bombardment was used to change the properties of these layers. The sp2 bonds were determined directly by reflected electron energy loss spectroscopy (REELS) and further characterization was made by Raman scattering. The polycrystalline diamond showed only very slight π-π* transition at 6.5 eV, but after Ar ion bombardment strong peak was formed but definitely shifted to lower energy compared to the well known π-π* transition of graphite. The as deposited PLD carbon films showed broad peak around 5eV clearly different than the π-π* transition (6.5eV). After Ar+ ion bombardment the peak was shifted also to lower energy range (4-5eV) with a remaining part at 6.5eV. The lower energy part of the peak can be correlated to the transition of sp3 sites, while this change in peak position was not detectable after ion bombardment of the reference HOPG sample, which does not contain sp3 hybridized carbon atoms.

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