Daminda Dahanayaka - Academia.edu (original) (raw)

Papers by Daminda Dahanayaka

Journal of the American Chemical Society, Apr 19, 2006

EDFA Technical Articles, May 1, 2022

Sample preparation is a critical step for dopant profiling of FinFET devices, especially when tar... more Sample preparation is a critical step for dopant profiling of FinFET devices, especially when targeting individual fins. This article describes a sample-preparation technique based on low-energy, shallow-angle ion milling and shows how it minimizes surface amorphization and improves scanning capacitance microscopy (SCM) signals representative of local active dopant concentration.

Optics Letters, Jul 27, 2007

We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to st... more We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to study local surface plasmon resonances in flat gold nanoparticles (FGNPs). Depending on nanoparticle dimensions, local near-field extinction spectra exhibit none, one, or two resonances in the range of visible wavelengths ͑1.6-2.6 eV͒. The measured spectra can be accurately described in terms of interference between the field emitted by the probe aperture and the field reradiated by driven FGNP surface plasmon oscillations. The measured resonances are in good agreement with those predicted by calculations using discrete dipole approximation. We observe that the amplitudes of these resonances are dependent upon the spatial position of the near-field probe, which indicates the possibility of spatially selective excitation of specific plasmon modes.

Langmuir, Aug 17, 2010

The cleavage of decanethioacetate (C10SAc) has been studied by 1 H nuclear magnetic resonance (NM... more The cleavage of decanethioacetate (C10SAc) has been studied by 1 H nuclear magnetic resonance (NMR) spectroscopy and scanning tunneling microscopy (STM) imaging of in situ prepared decanethiolate self-assembled monolayers (SAMs) on Au(111). Solutions of C10SAc (46 mM) and previously reported cleavage reagents (typically 58 mM) in CD 3 OD were monitored at 20°C by NMR spectroscopy. Cleavage by ammonium hydroxide, propylamine, or hydrochloric acid was not complete within 48 h; cleavage by potassium carbonate was complete within 24 h and that by potassium hydroxide or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) within 2 h. Similar cleavage rates were observed for phenylthioacetate. The degree of molecular ordering determined by STM imaging increased with increasing extent of in situ cleavage by these same reagents (2.5 mM C10SAc and 2.5 mM reagent in ethanol for 1 h, then 16 h immersion of Au/mica). Less effective cleavage reagents did not cleave the C10SAc sufficiently to decanethiol (C10SH) and gave mostly disordered SAMs. In contrast, KOH or DBU completely cleaved the C10SAc to C10SH and led to well-ordered SAMs composed of (√ 3 Â √ 3)R30°domains that are indistinguishable from SAMs grown from C10SH. Monolayer formation from thioacetates in the absence of cleavage agents is likely due to thiol or disulfide impurity in the thioacetates. Eliminating disulfide by using Bu 3 P as a sacrificial reductant also helped to produce good molecular order in the SAM. The methods presented here allow routine growth of molecularly ordered alkanethiolate SAMs from thioacetates using reagents of ordinary purity under ambient, benchtop conditions.

Nanotechnology, Jul 21, 2009

An important design approach for sensitive and robust surface enhanced Raman scattering (SERS) su... more An important design approach for sensitive and robust surface enhanced Raman scattering (SERS) substrates is the use of metal nanoparticle aggregates with nanometer tailored interstitial distances between their surfaces, in order to confine the electromagnetic energy. The nanostructural instability of the aggregates to agglomeration due to their strong van der Waals force poses a challenge for the preparation of large-scale, reliable SERS substrates. We present a novel route for preparing stable and highly active SERS substrates using polymer-metal fractal nanocomposites. This methodology is based on the unique morphology of fractal nanocomposite structures formed just below the percolation threshold that consists of extremely narrow (approximately 0.8 nm) interstitial polymer junctions between the Ag nanoparticle aggregates along with the appropriate nanoscale (<100 nm) surface roughness. Such nanomorphology allows the formation of well-defined and large numbers of hot spots where the localization of electromagnetic energy can result in very large enhancement of the Raman signal. We applied a simple plasma etching process to remove the polymer structures that allowed the formation of Ag structures with very uniform and controllable inter-particle gaps that were proved to provide significant SERS enhancement of typical biological systems such as double-stranded deoxyribonucleic acid (dsDNA). These advanced nanocomposite films could be used for the development of large-scale spectroscopy-based sensors for direct detection and analysis of various biological and chemical samples.

EDFA Technical Articles

Sample preparation is a critical step for dopant profiling of FinFET devices, especially when tar... more Sample preparation is a critical step for dopant profiling of FinFET devices, especially when targeting individual fins. This article describes a sample-preparation technique based on low-energy, shallow-angle ion milling and shows how it minimizes surface amorphization and improves scanning capacitance microscopy (SCM) signals representative of local active dopant concentration.

International Symposium for Testing and Failure Analysis, 2016

Physical failure analysis of nanoelectronic devices is typically performed using plan view or cro... more Physical failure analysis of nanoelectronic devices is typically performed using plan view or cross-sectional TEM, SEM or SPM techniques. While plan view SPM and SEM analyses are limited by the depth sensitivity of the technique, cross-sectional analysis requires at least approximate localization of the fail location within the device for effective sample preparation. Multi-finger wide 2D planar devices and multi-FIN 3D devices are structures which require an additional step in pinpointing the fail area within the device. This paper describes successful use of EBIC/EBAC techniques to localize the fail location within such devices in both the 22 nm and 14 nm technology nodes.

Bulletin of the American Physical Society, 2011

Submitted for the MAR11 Meeting of The American Physical Society The amazing kinetic stability of... more Submitted for the MAR11 Meeting of The American Physical Society The amazing kinetic stability of the high temperature (√ 3 × 6)rect. striped structure of decanethiol SAMs on Au(111) and other interesting properties. A scanning tunneling microscopy study. 1 LLOYD BUMM, DAMINDA DAHANAYAKA, ABHIJIT BISWAS, RONALD HALTER-MAN, The University of Oklahoma-We present an STM study of the properties of the high temperature (√ 3 × 6)rect. phase of decanethiol SAMs on Au (111). Although this phase is known, it has not been extensively studied. We show a simple reliable way to grow the (√ 3 × 6) rect. phase and show that its coverage is 75% of the normal (2 √ 3 × 3)rect. phase. Although it has lower density compared to the normal alkanethiol SAM structure, it shows a remarkable kinetic stability with respect to uptake of additional alkanethiol molecules and reversion to the normal (2 √ 3 × 3) rect. phase. Other properties of the (√ 3 × 6)rect. phase will be discussed.

Bulletin of the American Physical Society, 2014

Bulletin of the American Physical Society, 2019

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2019

For radio frequency (RF) wireless integrated circuits and devices fabricated on silicon-on-insula... more For radio frequency (RF) wireless integrated circuits and devices fabricated on silicon-on-insulator technologies, there has been indirect evidence of the presence of a parasitic native inversion layer, due to an effective trapped charge, “Q+,” at the interface of the buried oxide (BOX) and the underlying high resistivity p-type Si substrate in production level wafers. This inversion layer can have adverse implications for the RF performance of active devices fabricated for use in wireless technologies, notably the “RF switch.” In this study, the authors characterize the complementary-metal-oxide-semiconductor field effect RF transistor used in such a switch. The FET is built on the active epitaxial silicon layer on top of the BOX layer; its purpose is to control input and output RF signals in integrated wireless circuitry. Using scanning surface photovoltage microscopy, the authors present the first data to show quantitatively the extent of this inversion layer into the substrate. ...

Aps March Meeting Abstracts, Mar 1, 2004

We are investigating a novel substrate for use in single molecule electroluminescence experiments... more We are investigating a novel substrate for use in single molecule electroluminescence experiments with the Scanning Tunneling Microscope (STM). These substrates are composed of flat gold nanoparticles supported on indium tin oxide (ITO). Because ITO is an optical frequency insulator and a DC conductor, the optical spectroscopy of the particles are behave like they are supported on glass, yet are

Self-assembled monolayers (SAMs) are flexible substrates for surface chemistry. A wide variety of... more Self-assembled monolayers (SAMs) are flexible substrates for surface chemistry. A wide variety of SAM-surface functionalities can be prepared using alkanethiols with different terminal functional groups. Typically this requires a different alkanethiol for each. Another strategy uses a single alkanethiol to create a reactive surface which can be chemically modified post self-assembly. We are exploring azido-functional monolayers, which are reactive under mild conditions. The best known reaction is the copper catalyzed catalytic 1,3-dipolar cycloaddition with terminal alkynes. This approach has already been demonstrated for general surface chemical modification. We demonstrate molecularly-resolved STM imaging of these SAMs before and after the reaction. The surface structure affects the local reactivity and can be used to direct the reaction at the nanometer scale.

Nanoscience and Nanotechnology Letters, 2009

ABSTRACT We report fabrication of two different nanodielectric composites comprising a uniform bl... more ABSTRACT We report fabrication of two different nanodielectric composites comprising a uniform blend of inorganic–organic and inorganic–inorganic dielectric materials by a simple and single-step method of electron-beam-assisted vapor-phase codeposition. The fabrication method allowed ambient temperature (∼35 °C) generation of well-crystallized ultra-fine (∼5 nm) to relatively larger (∼150 nm) barium titanate BTO nanoparticles in lithium fluoride (LiF) and poly(methylmethacrylate) (PMMA) dielectric matrices. No high temperature sintering was performed. The fabricated nanodielectric composites showed unique nanometric interfacial polarization properties that resulted in very promising high-frequency (> 100 MHz) capacitor functions. The challenges of ferroelectric losses in the high-frequency were overcome and attributed to the possible interplay of polarization mechanisms contributed by the dielectric elements of nanostructured composites that allowed a frequency-independent capacitor performance. The best capacitor performance was achieved from as-deposited BTO-LiF nanodielectric systems that exhibited a flat capacitance density of about 10 nF/cm2 with the self resonance frequency occurring at around 150 MHz along with a low loss tangent of about 0.1 at 100 MHz, thus verifying the high-quality of the device structures. The fabricated nanodielectric composites may be suitable for a variety of high-frequency applications in miniaturized electronic systems.

We have developed a grid structure with a simple and robust address system to assist in locating ... more We have developed a grid structure with a simple and robust address system to assist in locating and relocating individual substrate-supported nanoparticles. We demonstrate application of our addressed grids for facile characterization of the SAME nanoparticles in multiple instruments. Our grids can be prepared on a variety of substrates using lift-off photolithography. We will show addressed grids of Cr/Au on

Optics Letters, 2007

We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to st... more We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to study local surface plasmon resonances in flat gold nanoparticles (FGNPs). Depending on nanoparticle dimensions, local near-field extinction spectra exhibit none, one, or two resonances in the range of visible wavelengths ͑1.6-2.6 eV͒. The measured spectra can be accurately described in terms of interference between the field emitted by the probe aperture and the field reradiated by driven FGNP surface plasmon oscillations. The measured resonances are in good agreement with those predicted by calculations using discrete dipole approximation. We observe that the amplitudes of these resonances are dependent upon the spatial position of the near-field probe, which indicates the possibility of spatially selective excitation of specific plasmon modes.

Journal of the American Chemical Society, Apr 19, 2006

EDFA Technical Articles, May 1, 2022

Sample preparation is a critical step for dopant profiling of FinFET devices, especially when tar... more Sample preparation is a critical step for dopant profiling of FinFET devices, especially when targeting individual fins. This article describes a sample-preparation technique based on low-energy, shallow-angle ion milling and shows how it minimizes surface amorphization and improves scanning capacitance microscopy (SCM) signals representative of local active dopant concentration.

Optics Letters, Jul 27, 2007

We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to st... more We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to study local surface plasmon resonances in flat gold nanoparticles (FGNPs). Depending on nanoparticle dimensions, local near-field extinction spectra exhibit none, one, or two resonances in the range of visible wavelengths ͑1.6-2.6 eV͒. The measured spectra can be accurately described in terms of interference between the field emitted by the probe aperture and the field reradiated by driven FGNP surface plasmon oscillations. The measured resonances are in good agreement with those predicted by calculations using discrete dipole approximation. We observe that the amplitudes of these resonances are dependent upon the spatial position of the near-field probe, which indicates the possibility of spatially selective excitation of specific plasmon modes.

Langmuir, Aug 17, 2010

The cleavage of decanethioacetate (C10SAc) has been studied by 1 H nuclear magnetic resonance (NM... more The cleavage of decanethioacetate (C10SAc) has been studied by 1 H nuclear magnetic resonance (NMR) spectroscopy and scanning tunneling microscopy (STM) imaging of in situ prepared decanethiolate self-assembled monolayers (SAMs) on Au(111). Solutions of C10SAc (46 mM) and previously reported cleavage reagents (typically 58 mM) in CD 3 OD were monitored at 20°C by NMR spectroscopy. Cleavage by ammonium hydroxide, propylamine, or hydrochloric acid was not complete within 48 h; cleavage by potassium carbonate was complete within 24 h and that by potassium hydroxide or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) within 2 h. Similar cleavage rates were observed for phenylthioacetate. The degree of molecular ordering determined by STM imaging increased with increasing extent of in situ cleavage by these same reagents (2.5 mM C10SAc and 2.5 mM reagent in ethanol for 1 h, then 16 h immersion of Au/mica). Less effective cleavage reagents did not cleave the C10SAc sufficiently to decanethiol (C10SH) and gave mostly disordered SAMs. In contrast, KOH or DBU completely cleaved the C10SAc to C10SH and led to well-ordered SAMs composed of (√ 3 Â √ 3)R30°domains that are indistinguishable from SAMs grown from C10SH. Monolayer formation from thioacetates in the absence of cleavage agents is likely due to thiol or disulfide impurity in the thioacetates. Eliminating disulfide by using Bu 3 P as a sacrificial reductant also helped to produce good molecular order in the SAM. The methods presented here allow routine growth of molecularly ordered alkanethiolate SAMs from thioacetates using reagents of ordinary purity under ambient, benchtop conditions.

Nanotechnology, Jul 21, 2009

An important design approach for sensitive and robust surface enhanced Raman scattering (SERS) su... more An important design approach for sensitive and robust surface enhanced Raman scattering (SERS) substrates is the use of metal nanoparticle aggregates with nanometer tailored interstitial distances between their surfaces, in order to confine the electromagnetic energy. The nanostructural instability of the aggregates to agglomeration due to their strong van der Waals force poses a challenge for the preparation of large-scale, reliable SERS substrates. We present a novel route for preparing stable and highly active SERS substrates using polymer-metal fractal nanocomposites. This methodology is based on the unique morphology of fractal nanocomposite structures formed just below the percolation threshold that consists of extremely narrow (approximately 0.8 nm) interstitial polymer junctions between the Ag nanoparticle aggregates along with the appropriate nanoscale (<100 nm) surface roughness. Such nanomorphology allows the formation of well-defined and large numbers of hot spots where the localization of electromagnetic energy can result in very large enhancement of the Raman signal. We applied a simple plasma etching process to remove the polymer structures that allowed the formation of Ag structures with very uniform and controllable inter-particle gaps that were proved to provide significant SERS enhancement of typical biological systems such as double-stranded deoxyribonucleic acid (dsDNA). These advanced nanocomposite films could be used for the development of large-scale spectroscopy-based sensors for direct detection and analysis of various biological and chemical samples.

EDFA Technical Articles

Sample preparation is a critical step for dopant profiling of FinFET devices, especially when tar... more Sample preparation is a critical step for dopant profiling of FinFET devices, especially when targeting individual fins. This article describes a sample-preparation technique based on low-energy, shallow-angle ion milling and shows how it minimizes surface amorphization and improves scanning capacitance microscopy (SCM) signals representative of local active dopant concentration.

International Symposium for Testing and Failure Analysis, 2016

Physical failure analysis of nanoelectronic devices is typically performed using plan view or cro... more Physical failure analysis of nanoelectronic devices is typically performed using plan view or cross-sectional TEM, SEM or SPM techniques. While plan view SPM and SEM analyses are limited by the depth sensitivity of the technique, cross-sectional analysis requires at least approximate localization of the fail location within the device for effective sample preparation. Multi-finger wide 2D planar devices and multi-FIN 3D devices are structures which require an additional step in pinpointing the fail area within the device. This paper describes successful use of EBIC/EBAC techniques to localize the fail location within such devices in both the 22 nm and 14 nm technology nodes.

Bulletin of the American Physical Society, 2011

Submitted for the MAR11 Meeting of The American Physical Society The amazing kinetic stability of... more Submitted for the MAR11 Meeting of The American Physical Society The amazing kinetic stability of the high temperature (√ 3 × 6)rect. striped structure of decanethiol SAMs on Au(111) and other interesting properties. A scanning tunneling microscopy study. 1 LLOYD BUMM, DAMINDA DAHANAYAKA, ABHIJIT BISWAS, RONALD HALTER-MAN, The University of Oklahoma-We present an STM study of the properties of the high temperature (√ 3 × 6)rect. phase of decanethiol SAMs on Au (111). Although this phase is known, it has not been extensively studied. We show a simple reliable way to grow the (√ 3 × 6) rect. phase and show that its coverage is 75% of the normal (2 √ 3 × 3)rect. phase. Although it has lower density compared to the normal alkanethiol SAM structure, it shows a remarkable kinetic stability with respect to uptake of additional alkanethiol molecules and reversion to the normal (2 √ 3 × 3) rect. phase. Other properties of the (√ 3 × 6)rect. phase will be discussed.

Bulletin of the American Physical Society, 2014

Bulletin of the American Physical Society, 2019

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2019

For radio frequency (RF) wireless integrated circuits and devices fabricated on silicon-on-insula... more For radio frequency (RF) wireless integrated circuits and devices fabricated on silicon-on-insulator technologies, there has been indirect evidence of the presence of a parasitic native inversion layer, due to an effective trapped charge, “Q+,” at the interface of the buried oxide (BOX) and the underlying high resistivity p-type Si substrate in production level wafers. This inversion layer can have adverse implications for the RF performance of active devices fabricated for use in wireless technologies, notably the “RF switch.” In this study, the authors characterize the complementary-metal-oxide-semiconductor field effect RF transistor used in such a switch. The FET is built on the active epitaxial silicon layer on top of the BOX layer; its purpose is to control input and output RF signals in integrated wireless circuitry. Using scanning surface photovoltage microscopy, the authors present the first data to show quantitatively the extent of this inversion layer into the substrate. ...

Aps March Meeting Abstracts, Mar 1, 2004

We are investigating a novel substrate for use in single molecule electroluminescence experiments... more We are investigating a novel substrate for use in single molecule electroluminescence experiments with the Scanning Tunneling Microscope (STM). These substrates are composed of flat gold nanoparticles supported on indium tin oxide (ITO). Because ITO is an optical frequency insulator and a DC conductor, the optical spectroscopy of the particles are behave like they are supported on glass, yet are

Self-assembled monolayers (SAMs) are flexible substrates for surface chemistry. A wide variety of... more Self-assembled monolayers (SAMs) are flexible substrates for surface chemistry. A wide variety of SAM-surface functionalities can be prepared using alkanethiols with different terminal functional groups. Typically this requires a different alkanethiol for each. Another strategy uses a single alkanethiol to create a reactive surface which can be chemically modified post self-assembly. We are exploring azido-functional monolayers, which are reactive under mild conditions. The best known reaction is the copper catalyzed catalytic 1,3-dipolar cycloaddition with terminal alkynes. This approach has already been demonstrated for general surface chemical modification. We demonstrate molecularly-resolved STM imaging of these SAMs before and after the reaction. The surface structure affects the local reactivity and can be used to direct the reaction at the nanometer scale.

Nanoscience and Nanotechnology Letters, 2009

ABSTRACT We report fabrication of two different nanodielectric composites comprising a uniform bl... more ABSTRACT We report fabrication of two different nanodielectric composites comprising a uniform blend of inorganic–organic and inorganic–inorganic dielectric materials by a simple and single-step method of electron-beam-assisted vapor-phase codeposition. The fabrication method allowed ambient temperature (∼35 °C) generation of well-crystallized ultra-fine (∼5 nm) to relatively larger (∼150 nm) barium titanate BTO nanoparticles in lithium fluoride (LiF) and poly(methylmethacrylate) (PMMA) dielectric matrices. No high temperature sintering was performed. The fabricated nanodielectric composites showed unique nanometric interfacial polarization properties that resulted in very promising high-frequency (> 100 MHz) capacitor functions. The challenges of ferroelectric losses in the high-frequency were overcome and attributed to the possible interplay of polarization mechanisms contributed by the dielectric elements of nanostructured composites that allowed a frequency-independent capacitor performance. The best capacitor performance was achieved from as-deposited BTO-LiF nanodielectric systems that exhibited a flat capacitance density of about 10 nF/cm2 with the self resonance frequency occurring at around 150 MHz along with a low loss tangent of about 0.1 at 100 MHz, thus verifying the high-quality of the device structures. The fabricated nanodielectric composites may be suitable for a variety of high-frequency applications in miniaturized electronic systems.

We have developed a grid structure with a simple and robust address system to assist in locating ... more We have developed a grid structure with a simple and robust address system to assist in locating and relocating individual substrate-supported nanoparticles. We demonstrate application of our addressed grids for facile characterization of the SAME nanoparticles in multiple instruments. Our grids can be prepared on a variety of substrates using lift-off photolithography. We will show addressed grids of Cr/Au on

Optics Letters, 2007

We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to st... more We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to study local surface plasmon resonances in flat gold nanoparticles (FGNPs). Depending on nanoparticle dimensions, local near-field extinction spectra exhibit none, one, or two resonances in the range of visible wavelengths ͑1.6-2.6 eV͒. The measured spectra can be accurately described in terms of interference between the field emitted by the probe aperture and the field reradiated by driven FGNP surface plasmon oscillations. The measured resonances are in good agreement with those predicted by calculations using discrete dipole approximation. We observe that the amplitudes of these resonances are dependent upon the spatial position of the near-field probe, which indicates the possibility of spatially selective excitation of specific plasmon modes.