N. Rowell - Academia.edu (original) (raw)

Papers by N. Rowell

Research paper thumbnail of (Invited) Photoluminescence Efficiency of Self-Assembled Germanium Dots

ECS Meeting Abstracts

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Research paper thumbnail of Fourier transform IR spectroscopy of Co2+ excitations in KZn1−xCoxF3

Infrared Physics

ABSTRACT

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Research paper thumbnail of Scattering of guided optical beams by surface acoustic waves in thin films

Journal of the Optical Society of America

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Research paper thumbnail of Infrared Dielectric Properties of In1-xGaxAs Epilayers on InP (100)

MRS Proceedings

ABSTRACTThe concentration dependence of optical phonons in strained In1-xGaxAs epilayers grown on... more ABSTRACTThe concentration dependence of optical phonons in strained In1-xGaxAs epilayers grown on InP (100) by chemical beam epitaxy has been characterized with oblique angle polarized far-infrared reflectivity measurements. In this powerful method, the reflectance spectra contain sharp Berreman peaks exactly at the optical phonon frequencies. For radiation polarized in the plane of incidence (p-polarized), peaks for both the TO and LO phonons were observed. For s-polarization only the TO modes were observed. For heavily doped substrates the TO film phonons were observed as reflectance minima, whereas for lightly doped substrates they were seen as maxima. The measured spectra were curve resolved to separate the effects of the various modes which included GaAs-like longitudinal and transverse optic (LO and TO), a disorder induced, and InAs-like LO and TO phonons. The dielectric response function and phonon frequency dependences for all modes were obtained versus Ga fraction for x fro...

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Research paper thumbnail of Optical Probing of Surface Waves in Thin Films

IEEE Transactions on Sonics and Ultrasonics

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Research paper thumbnail of Infrared photoluminescence of intrinsic InSb

Infrared Physics

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Research paper thumbnail of Radiation effects on heavily doped n-GaAs*

. RADECS 91 First European Conference on Radiation and its Effects on Devices and Systems, 2000

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Research paper thumbnail of Realization of an atomic microwave power standard

Conference Digest Conference on Precision Electromagnetic Measurements, 2000

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Research paper thumbnail of Trimming the size of InAs/InP quantum dots grown by CBE

Conference Proceedings. 2000 International Conference on Indium Phosphide and Related Materials (Cat. No.00CH37107), 2000

We have used transmission electron microscopy and low temperature photoluminescence to study the ... more We have used transmission electron microscopy and low temperature photoluminescence to study the growth by chemical beam epitaxy of self-assembled InAs/InP quantum dots. Square dots 30-40 nm in width were grown with a density of 1010 cm-2. By partially covering the dots with InP and exposing them to a phosphorus overpressure the mean height of the dots, and hence their

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Research paper thumbnail of Size-Dependent Quantum Efficiency of Luminescence in Self Assembled Germanium Nanocrystals

ECS Transactions, 2009

ABSTRACT

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Research paper thumbnail of Bright photoluminescence from ordered arrays of SiGe nanowires grown on Si(111)

Beilstein journal of nanotechnology, 2014

We report on the optical properties of SiGe nanowires (NWs) grown by molecular beam epitaxy (MBE)... more We report on the optical properties of SiGe nanowires (NWs) grown by molecular beam epitaxy (MBE) in ordered arrays on SiO2/Si(111) substrates. The production method employs Au catalysts with self-limited sizes deposited in SiO2-free sites opened-up in the substrate by focused ion beam patterning for the preferential nucleation and growth of these well-organized NWs. The NWs thus produced have a diameter of 200 nm, a length of 200 nm, and a Ge concentration x = 0.15. Their photoluminescence (PL) spectra were measured at low temperatures (from 6 to 25 K) with excitation at 405 and 458 nm. There are four major features in the energy range of interest (980-1120 meV) at energies of 1040.7, 1082.8, 1092.5, and 1098.5 meV, which are assigned to the NW-transverse optic (TO) Si-Si mode, NW-transverse acoustic (TA), Si-substrate-TO and NW-no-phonon (NP) lines, respectively. From these results the NW TA and TO phonon energies are found to be 15.7 and 57.8 meV, respectively, which agree very w...

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Research paper thumbnail of Raman Scattering Studies of Si1−xGex Layers Grown by Atmospheric Pressure Chemical Vapor Deposition

MRS Proceedings, 1992

ABSTRACTRoom temperature Raman spectra are reported of Si1−xGex layers on Si substrates (for 0.08... more ABSTRACTRoom temperature Raman spectra are reported of Si1−xGex layers on Si substrates (for 0.08≤x≤0.2). The samples were grown using atmospheric pressure chemical vapor deposition techniques. Layer thicknesses varied from 0.1 — 10μm. The relative frequency shift of the Si-Si phonon mode for the SiGe strained epilayers from an incommensurate pseudo-alloy of the same composition is used as a quantitative measure of the lattice strain. For thicknesses below a critical value the Raman data indicate that the films are highly strained and the growth is commensurate with the substrate whereas thicker films are partially or fully relaxed. Phonon lines are sensitive to the interfaces and alloy layers. The results are consistent with other characterization studies, such as TEM and X-ray rocking curve measurements, of the same samples.

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Research paper thumbnail of Proximity effects and the generalized Ginzburg-Landau equation

Physical Review B, 1975

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Research paper thumbnail of Photoluminescence mechanisms in thin Si1-xGex quantum wells

Physical review. B, Condensed matter, Jan 15, 1993

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Research paper thumbnail of Normal acoustic modes and Brillouin scattering in single-mode optical fibers

Physical Review B, 1979

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Research paper thumbnail of Infrared spectroscopies research activities in NRC

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Research paper thumbnail of <title>Analysis Of Doping Superlattices Grown By Si MBE</title>

Quantum Well and Superlattice Physics II, 1988

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Research paper thumbnail of <title>Photoluminescence quenching of colloidal silver nanoparticle on porous silicon</title>

Photonic Applications in Biosensing and Imaging, 2005

Photoluminescent porous Si (pSi) is a potentially attractive material for biosensor devices. Its ... more Photoluminescent porous Si (pSi) is a potentially attractive material for biosensor devices. Its ease of fabrication, large active surface area and unique optical properties are just some important attributes. Among other transduction techniques, it is possible to monitor the onset of molecular binding events through the effective quenching of the bright pSi photoluminescence. Here we present the study of effective

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Research paper thumbnail of Infrared Spectroscopic Characterization of Functional Monolayers on Silicon

MRS Proceedings, 2005

Infrared vibrational spectroscopy in an attenuated total reflection geometry has been employed to... more Infrared vibrational spectroscopy in an attenuated total reflection geometry has been employed to investigate the presence of organic and inorganic thin layers on Si-wafer surfaces. Three different processes were compared for surface contaminant removal; microwave plasma, UV-ozone, and a piranha solution cleaning. The CH vibrations at 2928 and 2856 cm-1 characteristic of organic contaminants were monitored before and after each cleaning procedure to determine how well it removed surface contaminants. We found that native oxide removal from the Si surface should only be carried out after a cleaning essay. We observed that surface oxide removal exposed a hydrophobic bare Si surface, attracting organic molecules present in solution or the ambient. A large increase of the CH vibrational signature was observed for a Si wafer after an HF dip. A combination of plasma cleaning followed by UV-Ozone treatment was found the most effective one for Si wafer cleaning. We were able to evaluate the...

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Research paper thumbnail of Colloidal Silver Nanoparticle Induced Photoluminescence Quench on the Surface Functionalized Planar Si

MRS Proceedings, 2005

The photoluminescence (PL) intensity of undecylenic acid surface functionalized planar Si (001) w... more The photoluminescence (PL) intensity of undecylenic acid surface functionalized planar Si (001) was investigated in the presence of colloidal Ag nanoparticles. The acid passivated Si surface has a weak PL at 1125 nm. Upon exposure to a Ag nanoparticle sol, the PL quenched exponentially with a characteristic decay time of ∼ 18 minutes. It is known that the metal mediated charge-transfer process provides a pathway for energy decay and leads to a quenching of luminescence in light emitting material. An in-situ study of the surface passivated Si revealed that the Ag nanoparticle was likely to have come into contact or was sited close enough to the semiconductor surface through adsorption to cause effective PL quenching.

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Research paper thumbnail of (Invited) Photoluminescence Efficiency of Self-Assembled Germanium Dots

ECS Meeting Abstracts

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Research paper thumbnail of Fourier transform IR spectroscopy of Co2+ excitations in KZn1−xCoxF3

Infrared Physics

ABSTRACT

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Research paper thumbnail of Scattering of guided optical beams by surface acoustic waves in thin films

Journal of the Optical Society of America

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Infrared Dielectric Properties of In1-xGaxAs Epilayers on InP (100)

MRS Proceedings

ABSTRACTThe concentration dependence of optical phonons in strained In1-xGaxAs epilayers grown on... more ABSTRACTThe concentration dependence of optical phonons in strained In1-xGaxAs epilayers grown on InP (100) by chemical beam epitaxy has been characterized with oblique angle polarized far-infrared reflectivity measurements. In this powerful method, the reflectance spectra contain sharp Berreman peaks exactly at the optical phonon frequencies. For radiation polarized in the plane of incidence (p-polarized), peaks for both the TO and LO phonons were observed. For s-polarization only the TO modes were observed. For heavily doped substrates the TO film phonons were observed as reflectance minima, whereas for lightly doped substrates they were seen as maxima. The measured spectra were curve resolved to separate the effects of the various modes which included GaAs-like longitudinal and transverse optic (LO and TO), a disorder induced, and InAs-like LO and TO phonons. The dielectric response function and phonon frequency dependences for all modes were obtained versus Ga fraction for x fro...

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Research paper thumbnail of Optical Probing of Surface Waves in Thin Films

IEEE Transactions on Sonics and Ultrasonics

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Research paper thumbnail of Infrared photoluminescence of intrinsic InSb

Infrared Physics

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Research paper thumbnail of Radiation effects on heavily doped n-GaAs*

. RADECS 91 First European Conference on Radiation and its Effects on Devices and Systems, 2000

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Research paper thumbnail of Realization of an atomic microwave power standard

Conference Digest Conference on Precision Electromagnetic Measurements, 2000

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Trimming the size of InAs/InP quantum dots grown by CBE

Conference Proceedings. 2000 International Conference on Indium Phosphide and Related Materials (Cat. No.00CH37107), 2000

We have used transmission electron microscopy and low temperature photoluminescence to study the ... more We have used transmission electron microscopy and low temperature photoluminescence to study the growth by chemical beam epitaxy of self-assembled InAs/InP quantum dots. Square dots 30-40 nm in width were grown with a density of 1010 cm-2. By partially covering the dots with InP and exposing them to a phosphorus overpressure the mean height of the dots, and hence their

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Size-Dependent Quantum Efficiency of Luminescence in Self Assembled Germanium Nanocrystals

ECS Transactions, 2009

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Bright photoluminescence from ordered arrays of SiGe nanowires grown on Si(111)

Beilstein journal of nanotechnology, 2014

We report on the optical properties of SiGe nanowires (NWs) grown by molecular beam epitaxy (MBE)... more We report on the optical properties of SiGe nanowires (NWs) grown by molecular beam epitaxy (MBE) in ordered arrays on SiO2/Si(111) substrates. The production method employs Au catalysts with self-limited sizes deposited in SiO2-free sites opened-up in the substrate by focused ion beam patterning for the preferential nucleation and growth of these well-organized NWs. The NWs thus produced have a diameter of 200 nm, a length of 200 nm, and a Ge concentration x = 0.15. Their photoluminescence (PL) spectra were measured at low temperatures (from 6 to 25 K) with excitation at 405 and 458 nm. There are four major features in the energy range of interest (980-1120 meV) at energies of 1040.7, 1082.8, 1092.5, and 1098.5 meV, which are assigned to the NW-transverse optic (TO) Si-Si mode, NW-transverse acoustic (TA), Si-substrate-TO and NW-no-phonon (NP) lines, respectively. From these results the NW TA and TO phonon energies are found to be 15.7 and 57.8 meV, respectively, which agree very w...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Raman Scattering Studies of Si1−xGex Layers Grown by Atmospheric Pressure Chemical Vapor Deposition

MRS Proceedings, 1992

ABSTRACTRoom temperature Raman spectra are reported of Si1−xGex layers on Si substrates (for 0.08... more ABSTRACTRoom temperature Raman spectra are reported of Si1−xGex layers on Si substrates (for 0.08≤x≤0.2). The samples were grown using atmospheric pressure chemical vapor deposition techniques. Layer thicknesses varied from 0.1 — 10μm. The relative frequency shift of the Si-Si phonon mode for the SiGe strained epilayers from an incommensurate pseudo-alloy of the same composition is used as a quantitative measure of the lattice strain. For thicknesses below a critical value the Raman data indicate that the films are highly strained and the growth is commensurate with the substrate whereas thicker films are partially or fully relaxed. Phonon lines are sensitive to the interfaces and alloy layers. The results are consistent with other characterization studies, such as TEM and X-ray rocking curve measurements, of the same samples.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Proximity effects and the generalized Ginzburg-Landau equation

Physical Review B, 1975

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Photoluminescence mechanisms in thin Si1-xGex quantum wells

Physical review. B, Condensed matter, Jan 15, 1993

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Normal acoustic modes and Brillouin scattering in single-mode optical fibers

Physical Review B, 1979

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Infrared spectroscopies research activities in NRC

Bookmarks Related papers MentionsView impact

Research paper thumbnail of <title>Analysis Of Doping Superlattices Grown By Si MBE</title>

Quantum Well and Superlattice Physics II, 1988

Bookmarks Related papers MentionsView impact

Research paper thumbnail of <title>Photoluminescence quenching of colloidal silver nanoparticle on porous silicon</title>

Photonic Applications in Biosensing and Imaging, 2005

Photoluminescent porous Si (pSi) is a potentially attractive material for biosensor devices. Its ... more Photoluminescent porous Si (pSi) is a potentially attractive material for biosensor devices. Its ease of fabrication, large active surface area and unique optical properties are just some important attributes. Among other transduction techniques, it is possible to monitor the onset of molecular binding events through the effective quenching of the bright pSi photoluminescence. Here we present the study of effective

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Infrared Spectroscopic Characterization of Functional Monolayers on Silicon

MRS Proceedings, 2005

Infrared vibrational spectroscopy in an attenuated total reflection geometry has been employed to... more Infrared vibrational spectroscopy in an attenuated total reflection geometry has been employed to investigate the presence of organic and inorganic thin layers on Si-wafer surfaces. Three different processes were compared for surface contaminant removal; microwave plasma, UV-ozone, and a piranha solution cleaning. The CH vibrations at 2928 and 2856 cm-1 characteristic of organic contaminants were monitored before and after each cleaning procedure to determine how well it removed surface contaminants. We found that native oxide removal from the Si surface should only be carried out after a cleaning essay. We observed that surface oxide removal exposed a hydrophobic bare Si surface, attracting organic molecules present in solution or the ambient. A large increase of the CH vibrational signature was observed for a Si wafer after an HF dip. A combination of plasma cleaning followed by UV-Ozone treatment was found the most effective one for Si wafer cleaning. We were able to evaluate the...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Colloidal Silver Nanoparticle Induced Photoluminescence Quench on the Surface Functionalized Planar Si

MRS Proceedings, 2005

The photoluminescence (PL) intensity of undecylenic acid surface functionalized planar Si (001) w... more The photoluminescence (PL) intensity of undecylenic acid surface functionalized planar Si (001) was investigated in the presence of colloidal Ag nanoparticles. The acid passivated Si surface has a weak PL at 1125 nm. Upon exposure to a Ag nanoparticle sol, the PL quenched exponentially with a characteristic decay time of ∼ 18 minutes. It is known that the metal mediated charge-transfer process provides a pathway for energy decay and leads to a quenching of luminescence in light emitting material. An in-situ study of the surface passivated Si revealed that the Ag nanoparticle was likely to have come into contact or was sited close enough to the semiconductor surface through adsorption to cause effective PL quenching.

Bookmarks Related papers MentionsView impact