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'Physics' in all fields;
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Displaying Results 51 - 75 of 3911 on page 3 of 157
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The new physics of non-equilibrium condensates: insights from classical dynamics
(2007)
EASTHAM, PAUL
The new physics of non-equilibrium condensates: insights from classical dynamics
(2007)
EASTHAM, PAUL
Abstract:
We discuss the dynamics of classical Dicke-type models, aiming to clarify the mechanisms by which coherent states could develop in potentially non-equilibrium systems such as semiconductor microcavities. We present simulations of an undamped model which show spontaneous coherent states with persistent oscillations in the magnitude of the order parameter. These states are generalisations of superradiant ringing to the case of inhomogeneous broadening. They correspond to the persistent gap oscillations proposed in fermionic atomic condensates, and arise from a variety of initial conditions. We show that introducing randomness into the couplings can suppress the oscillations, leading to a limiting dynamics with a time-independent order parameter. This demonstrates that non-equilibrium generalisations of polariton condensates can be created even without dissipation. We explain the dynamical origins of the coherence in terms of instabilities of the normal state, and consider how it can a...
http://hdl.handle.net/2262/49379
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Influence of miscut direction on magnetic anisotropy of magnetite films grown on vicinal MgO (100)
(2010)
SHVETS, IGOR; ARORA, SUNIL; RAMOS, RAFAEL
Influence of miscut direction on magnetic anisotropy of magnetite films grown on vicinal MgO (100)
(2010)
SHVETS, IGOR; ARORA, SUNIL; RAMOS, RAFAEL
Abstract:
Ferromagnetic resonance (FMR) was used to study the influence of miscut direction on the in-plane fourfold and uniaxial magnetic anisotropies of epitaxial Fe3O4 films grown on vicinal MgO (100) surfaces. In-plane angular dependent measurements at room temperature on Fe3O4 films on two different miscut directions (miscut along < 011 > and < 010 > directions) of MgO showed the presence of both in-plane fourfold (cubic) and in-plane uniaxial anisotropies. Temperature dependent FMR investigations show that the in-plane fourfold anisotropy constant (K-4) is approximately the same for both samples at room temperature. The magnitude of K-4 increases gradually with decreasing temperature and changes sign from negative to positive values at 130 K. This behavior is consistent with that of bulk magnetite. In addition to K-4, we find an additional uniaxial component (K-2), whose strength is quite different for the different miscut directions. The magnitude of K-2 shows very little o...
http://hdl.handle.net/2262/54949
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Variation of the electronic functionality of self-seeded germanium nanowires through synthesis determined core-shell interface states
(2015)
Connaughton, Stephen
Variation of the electronic functionality of self-seeded germanium nanowires through synthesis determined core-shell interface states
(2015)
Connaughton, Stephen
Abstract:
THESIS 10692
Bottom up grown germanium nanowires may have an important role to play in future electronic devices. While the electrical properties of nanowires grown using a metallic seed as a catalyst have been extensively reported we study self-seeded nanowires in this thesis. Such wires are core-shell in nature and are grown without any intentional doping. Self-seeded nanowires have been previously proposed as an attractive alternative to conventionally grown wires due the alleviation of complications arising from unintentional doping from the metallic seed.
http://hdl.handle.net/2262/77547
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Computer simulation in low-temperature plasma physics: future challenges
(2016)
Turner, Miles M.
Computer simulation in low-temperature plasma physics: future challenges
(2016)
Turner, Miles M.
Abstract:
Computer simulations can be carried out with various aims. Perhaps the most challenging is prediction under conditions where experiments are difficult or inaccessible, especially when failure to predict adequately may have unhappy consequences. There is, probably, not much confidence at present in the capability of low-temperature plasma physics simulations in such a context. Other fields have attempted to meet this challenge using a collection of techniques collectively known as Verification and Validation, or V&V. These are methods for enhancing confidence in the correctness and fidelity of computer simulations. This paper surveys these techniques and discusses their application to improvements of simulation capability in low-temperature plasma physics.
http://doras.dcu.ie/21802/
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A model for tailored-waveform radiofrequency sheaths
(2017)
Chabert, Pascal; Turner, Miles M.
A model for tailored-waveform radiofrequency sheaths
(2017)
Chabert, Pascal; Turner, Miles M.
Abstract:
The sheath physics of radiofrequency plasmas excited by a sinusoidal waveform is reasonably well understood, but the existing models are complicated and are not easily extended to the more complex waveforms recently introduced in applications. Turner and Chabert (2014 Appl. Phys. Lett. 104 164102) proposed a model for collisionless sheaths that can easily be solved for arbitrary waveforms. In this paper we extend this model to the case of collisional sheaths in the intermediate pressure regime. Analytical expressions are derived for the electric field, the electric potential and the density profiles in the sheath region. The collisionless and collisional models are compared for a pulsed-voltage waveform.
http://doras.dcu.ie/21812/
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Further studies in self-directed learning in physics at the University of Limerick, Ireland
(2018)
McCauley, Veronica; McClelland, George
Further studies in self-directed learning in physics at the University of Limerick, Ireland
(2018)
McCauley, Veronica; McClelland, George
Abstract:
This article reports on two SDL studies of undergraduate physics students and postgraduate science students at the University of Limerick, Ireland. Initial studies (McCauley and McClelland, 2001) indicated that the majority of undergraduate physics students are average and below in their readiness to self-direct their learning. Our further investigations lend credence and further support these findings. Results also indicate that small interventions of the nature described here are not successful in evoking large changes, yet they are successful in the exploration of change. The authors propose that an intervention on a much greater scale is warranted, throughout not only the full course, but, in time, across all courses, which all play a part in forming students models of learning.
http://hdl.handle.net/10379/7295
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Designing physics video hooks for science students
(2018)
McHugh, Martin; McCauley, Veronica
Designing physics video hooks for science students
(2018)
McHugh, Martin; McCauley, Veronica
Abstract:
This paper offers an insight into the design structure of physics video hooks that were developed by the Science Education Resource design team in the school of education (SOE) in National University of Ireland, Galway (NUI Galway). A hook, is an instructional technique used to stimulate student attention (Hunter 1994, Lemov 2010), interest (Jewett 2013) and engagement (McCrory 2011, Riendeau 2013). The physics video hooks followed a design framework that is illustrated below by breaking down the centre of gravity (COG) hook. Various design principles and elements embedded within the COG hook are presented with examples and the time they occur within the video. The intention of this article is that the design can be replicated and modified to aid teachers and designers in the development of a multitude of classroom based multimedia resources.
The NUI Galway Hardiman Scholarship.
http://hdl.handle.net/10379/7304
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Magnetic Characteristics of Sunspot Groups and their Role in Producing Adverse Space Weather
(2019)
MCCLOSKEY, AOIFE ELIZABETH
Magnetic Characteristics of Sunspot Groups and their Role in Producing Adverse Space Weather
(2019)
MCCLOSKEY, AOIFE ELIZABETH
Abstract:
The energy that powers solar flares is known to come from magnetic energy stored in sunspot groups, but the precise conditions required and processes involved in energy release remain unclear. The likelihood of flaring is directly related to the complexity of the magnetic field, such that larger, more complex sunspot groups produce larger more frequent flares than smaller, simple sunspot groups. The research in this thesis aims to investigate the evolution of sunspot complexity to gain greater understanding of how sunspot groups produce flares, with the intention of improving upon current methods of flare prediction. Firstly, the temporal evolution of sunspot groups in terms of their white-light structural complexity (McIntosh classification) was examined during Solar Cycle 22 (SC22). It was found that over a 24-hr period the majority,??60%, of sunspot groups do not evolve in terms of the parameters described by ...
http://hdl.handle.net/2262/86182
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Theoretical and experimental study on electron transport in oxygen-plasma-treated monolayer MoS2
(2019)
LI, GEN
Theoretical and experimental study on electron transport in oxygen-plasma-treated monolayer MoS2
(2019)
LI, GEN
Abstract:
In recent years, two dimensional (2D) molybdenum disul?de (MoS2) has attracted a wide range of interest due to its interesting physics properties, such as valley electronics and quantum spin Hall e?ect, and its potential applications for the semiconductor industry such as in ?eld-e?ect transistors (FETs) and photodetectors. Chapters 1 to 4 contain background knowledge related to this work, including the crystal structures of MoS2, plasma engineering, density functional theory (DFT) and the transfer matrix method (TMM). In Chapter 5, we introduce the experimental instruments used in this work, including mechanical exfoliation, electron beam lithography (EBL), Atomic Force Microscopy (AFM), Raman and photoluminescene (PL) spectroscopy, and an electric measurement system. In Chapter 6, we utilize radio-frequency oxygen plasma to treat 2D MoS2 FET to enhance the performance of the device. We study the surface morphology of the same device before and after two-second rapid plasma trea...
http://hdl.handle.net/2262/88798
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Uniaxial stress studies of the Be pair bound exciton absorption spectrum in silicon
(1984)
Mulligan, F.J.; Henry, M.O.; Moloney, K.A.; Treacy, J.; Lightowlers, E.C.
Uniaxial stress studies of the Be pair bound exciton absorption spectrum in silicon
(1984)
Mulligan, F.J.; Henry, M.O.; Moloney, K.A.; Treacy, J.; Lightowlers, E.C.
Abstract:
The authors report the results of preliminary uniaxial stress studies of the beryllium pair isoelectronic bound exciton absorption spectrum in silicon. The results confirm that the exciton behaves as an isoelectronic acceptor.
http://mural.maynoothuniversity.ie/814/
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Pilot Scheme for Learning Support for 1st Year Experimental Physics
(2012)
Trappe, Neil
Pilot Scheme for Learning Support for 1st Year Experimental Physics
(2012)
Trappe, Neil
Abstract:
Abstract included in text.
http://mural.maynoothuniversity.ie/4312/
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Non-locality of non-Abelian anyons
(2009)
Brennen, G.K.; Iblisdir, S.; Pachos, J.K.; Slingerland, Joost
Non-locality of non-Abelian anyons
(2009)
Brennen, G.K.; Iblisdir, S.; Pachos, J.K.; Slingerland, Joost
Abstract:
Entangled states of quantum systems can give rise to measurement correlations of separated observers that cannot be described by local hidden variable theories. Usually, it is assumed that entanglement between particles is generated due to some distance-dependent interaction. Yet anyonic particles in two dimensions have a nontrivial interaction that is purely topological in nature. In other words, it does not depend on the distance between two particles, but rather on their exchange history. The information encoded in anyons is inherently non-local even in the single subsystem level making the treatment of anyons nonconventional. We describe a protocol to reveal the non-locality of anyons in terms of correlations in the outcomes of measurements in two separated regions. This gives a clear operational measure of non-locality for anyonic states and it opens up the possibility to test Bell inequalities in quantum Hall liquids or spin lattices.
http://mural.maynoothuniversity.ie/1878/
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Real-time plasma control in a dual-frequency, confined plasma etcher
(2008)
Milosavljević, V.; Ellingboe, A.R.; Gaman, C.; Ringwood, John
Real-time plasma control in a dual-frequency, confined plasma etcher
(2008)
Milosavljević, V.; Ellingboe, A.R.; Gaman, C.; Ringwood, John
Abstract:
The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2 flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor signals onto the control inputs, allowing compensation of the interaction between control paths. The compensated sensor signals and compensated set–points are then used as inputs to proportional-integral-derivative controllers to adjust radio frequency power and oxygen flow to yield the desired ion fl...
http://mural.maynoothuniversity.ie/6897/
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Effects of excitonic diffusion on stimulated emission in nanocrystalline ZnO
(2006)
Tobin, Gerard; McGlynn, Enda; Henry, Martin O.; Mosnier, Jean-Paul; de Posada, Eduardo;...
Effects of excitonic diffusion on stimulated emission in nanocrystalline ZnO
(2006)
Tobin, Gerard; McGlynn, Enda; Henry, Martin O.; Mosnier, Jean-Paul; de Posada, Eduardo; Lunney, James G.
Abstract:
We present optically-pumped emission data for ZnO, showing that high excitation effects and stimulated emission / lasing are observed in nanocrystalline ZnO thin films at room temperature, although such effects are not seen in bulk material of better optical quality. A simple model of exciton density profiles is developed which explains our results and those of other authors. Inhibition of exciton diffusion in nanocrystalline samples compared to bulk significantly increases exciton densities in the former, leading, via the nonlinear dependence of emission in the exciton bands on the pump intensity, to large increases in emission and to stimulated emission.
http://doras.dcu.ie/2/
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Single-shot characterization of independent femtosecond extreme ultraviolet free electron and infrared laser pulses
(2007)
Dardis, John; Kavanagh, Kevin D.; Pedregosa-Gutierrez, Jofre; Yeates, Patrick; Kennedy,...
Single-shot characterization of independent femtosecond extreme ultraviolet free electron and infrared laser pulses
(2007)
Dardis, John; Kavanagh, Kevin D.; Pedregosa-Gutierrez, Jofre; Yeates, Patrick; Kennedy, Eugene T.; Costello, John T.
Abstract:
Two-color above threshold ionization of helium and xenon has been used to analyze the synchronization between individual pulses of the femtosecond extreme ultraviolet (XUV) Free electron LASer in Hamburg and an independent intense 120 fs mode-locked Ti:Sa laser. Characteristic sidebands appear in the photoelectron spectra when the two pulses overlap spatially and temporally. The cross-correlation curve points to a 250 fs r.m.s. jitter between the two sources at the experiment. A more precise determination of the temporal fluctuation between the XUV and infrared pulses is obtained through the analysis of the single-shot sideband intensities.
http://doras.dcu.ie/74/
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Photoionization experiments with the ultrafast EUV laser 'FLASH' - free electron laser in Hamburg
(2007)
Costello, John T.
Photoionization experiments with the ultrafast EUV laser 'FLASH' - free electron laser in Hamburg
(2007)
Costello, John T.
Abstract:
The advent of mirror-less Free Electron Lasers emitting polarised and coherent 'laser-like' beams of high peak (> 1GW) and average (up to 100mW) powers in the extreme-UV (EUV) and X-ray bands of the electromagnetic spectrum heralds a new era in the study of the photoelectric effect. The unprecedented photon flux (~1013 photons per pulse) opens up to scrutiny processes with cross sections considered hitherto unfeasibly small to probe with conventional EUV sources such as synchrotrons and laser plasmas. The peak intensity of the focussed pulse train (<1013 W/cm2), combined with the high photon energy, ports non-linear optics and spectroscopy into a regime where inner shell electrons can become the predominant mediator of the photon matter interaction. Few photon, few electron photoionization processes are made amenable to study for the first time and the wavelength tunability of the FEL permits resonances to come into play. In combination with ultrafast optical lasers,...
http://doras.dcu.ie/111/
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Growth of CuCl thin films by magnetron sputtering for ultraviolet optoelectronic applications
(2006)
Natarajan, Gomathi; Daniels, Stephen; Cameron, David C.; O'Reilly, Lisa; Mitra, An...
Growth of CuCl thin films by magnetron sputtering for ultraviolet optoelectronic applications
(2006)
Natarajan, Gomathi; Daniels, Stephen; Cameron, David C.; O'Reilly, Lisa; Mitra, Anirban; McNally, Patrick J.; Lucas, Francis Olabanji; Rajendra Kumar, Ramasamy Thangavelu; Reid, Ian; Bradley, Ann Louise
Abstract:
Copper (I) chloride (CuCl) is a potential candidate for ultraviolet (UV) optoelectronics due to its close lattice match with Si (mismatch less than 0.4%) and a high UV excitonic emission at room temperature. CuCl thin films were deposited using radio frequency magnetron sputtering technique. The influence of target to substrate distance (dts) and sputtering pressure on the composition, microstructure, and UV emission properties of the films were analyzed. The films deposited with shorter target to substrate spacing (dts=3 cm) were found to be nonstoichiometric, and the film stoichiometry improves when the substrate is moved away from the target (dts=4.5 and 6 cm). A further increase in the spacing results in poor crystalline quality. The grain interface area increases when the sputtering pressure is increased from 1.1×10–³ to 1×10–² mbar at dts=6 cm. Room temperature cathodoluminescence spectrum shows an intense and sharp UV exciton (Z₃) emission at ~385 nm with a full width at...
http://doras.dcu.ie/196/
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Electron heating mode transitions in dual frequency capacitive discharges
(2006)
Turner, Miles M.; Chabert, Pascal
Electron heating mode transitions in dual frequency capacitive discharges
(2006)
Turner, Miles M.; Chabert, Pascal
Abstract:
The authors consider electron heating in the sheath regions of capacitive discharges excited by a combination of two frequencies, one much higher than the other. There is a common supposition that in such discharges the higher frequency is the dominant source of electron heating. In this letter, the authors discuss closed analytic expressions quantifying the Ohmic and collisionless electron heating in a dual frequency discharge. In both cases, the authors show that the lower frequency parameters strongly influence the heating effect. Moreover, this influence is parametrically different, so that the dominant heating mechanism may be changed by varying the low frequency current density.
http://doras.dcu.ie/213/
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Kinetic properties of particle-in-cell simulations compromised by Monte Carlo collisions
(2006)
Turner, Miles M.
Kinetic properties of particle-in-cell simulations compromised by Monte Carlo collisions
(2006)
Turner, Miles M.
Abstract:
he particle-in-cell method with Monte Carlo collisions is frequently used when a detailed kinetic simulation of a weakly collisional plasma is required. In such cases, one usually desires, inter alia, an accurate calculation of the particle distribution functions in velocity space. However, velocity space diffusion affects most, perhaps all, kinetic simulations to some degree, leading to numerical thermalization (i.e., relaxation of the velocity distribution toward a Maxwellian), and consequently distortion of the true velocity distribution functions, among other undesirable effects. The rate of such thermalization can be considered a figure of merit for kinetic simulations. This article shows that, contrary to previous assumption, the addition of Monte Carlo collisions to a one-dimensional particle-in-cell simulation seriously degrades certain properties of the simulation. In particular, the thermalization time can be reduced by as much as three orders of magnitude. This effect mak...
http://doras.dcu.ie/214/
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Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas
(2010)
Hough, Pádraig; McLoughlin, Conor; Harilal, Sivanandan S.; Mosnier, Jean-Paul; Costello...
Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas
(2010)
Hough, Pádraig; McLoughlin, Conor; Harilal, Sivanandan S.; Mosnier, Jean-Paul; Costello, John T.
Abstract:
The expansion dynamics of ion and neutral species in laterally colliding laser produced aluminum plasmas have been investigated using time and space resolved optical emission spectroscopies and spectrally and angularly resolved fast imaging. The emission results highlight a difference in neutral atom and ion distributions in the stagnation layer where, at a time delay of 80 ns, the neutral atoms are localized in the vicinity of the target surface 1 mm from the target surface while singly and doubly charged ions lie predominantly at larger distances, 1.5 and 2 mm, respectively. The imaging results show that the ions were found to form a well defined, but compressed, stagnation layer at the collision front between the two seed plasmas at early times (Dt ~ 80 ns). On the other hand, the excited neutrals were observed to form a V-shaped emission feature at the outer regions of the collision front with enhanced neutral emission in the less dense, cooler regions of the stagnation layer.
http://doras.dcu.ie/15135/
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Gold surface with gold nitride–a surface enhanced Raman scattering active substrate
(2009)
Brieva, A.C.; Alves, Luis; Krishnamurthy, Satheesh; Siller, Lidija
Gold surface with gold nitride–a surface enhanced Raman scattering active substrate
(2009)
Brieva, A.C.; Alves, Luis; Krishnamurthy, Satheesh; Siller, Lidija
Abstract:
The nitration of gold surfaces is a nonpolluting method, which can lead to large scale production of substrates with remarkable properties and applications. We present a topographical study of the nanoscale structure of the gold nitride surfaces produced by radio frequency (rf) nitrogen plasma etching of thin gold films. Atomic force microscopy images taken after rf etching reveal the striking appearance of the cluster assembly with large clusters surrounded by small clusters (7.9±1.4 and 2.3±0.9 nm, respectively) appearing to exhibit an attractive interaction. We discuss the possible mechanism for this attraction based on a colloid model by Messina et al. [Phys. Rev. Lett. 85, 872 (2000) ]. This surface exhibits a notable surface enhanced Raman scattering effect demonstrated with L-alanine and rhodamine-6G. The significance of this work is that we found that this SERS active gold nitride surface can be prepared in just one step: by nitrogen plasma etching a thin gold film. Until no...
http://doras.dcu.ie/15352/
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Degradation and breakdown characteristics of thin MgO dielectric layers
(2010)
O'Connor, Robert; Hughes, Greg; Casey, Patrick; Newcomb, Simon B.
Degradation and breakdown characteristics of thin MgO dielectric layers
(2010)
O'Connor, Robert; Hughes, Greg; Casey, Patrick; Newcomb, Simon B.
Abstract:
MgO has been suggested as a possible high-k dielectric for future complementary metal-oxide semiconductor processes. In this work, the time dependent dielectric breakdown (TDDB) characteristics of 20 nm MgO films are discussed. Stress induced leakage current measurements indicate that the low measured Weibull slopes of the TDDB distributions for both n-type and p-type devices cannot be attributed to a lower trap generation rate than for SiO2. This suggests that much fewer defects are required to trigger breakdown in MgO under voltage stress than is the case for SiO2 or other metal-oxide dielectrics. This in turn explains the progressive nature of the breakdown in these films which is observed both in this work and elsewhere. The reason fewer defects are required is attributed to the morphology of the films.
http://doras.dcu.ie/15579/
Marked
Mark
Photoemission study of the SiO₂conversion mechanism to magnesium silicate
(2010)
Casey, Patrick; Hughes, Greg
Photoemission study of the SiO₂conversion mechanism to magnesium silicate
(2010)
Casey, Patrick; Hughes, Greg
Abstract:
The objective of this work is to investigate interface chemistries which minimize the interfacial silicon oxide transition region at Si/high-k dielectric interfaces. We report on the mechanism by which a silicon native oxide layer is converted into magnesium silicate. The deposition of metal Mg onto a SiO native oxide surface resulted in the formation of a magnesium silicide in addition to substochiometric silicon oxides and a significant decrease in the oxidised silicon signal. Annealing to 300 °C resulted in the decomposition of the magnesium silicide, oxidation of the Mg, and the desorption of excess metallic Mg. Subsequent annealing to 500 °C resulted in converting the SiO2 into magnesium silicate. The results suggest that the decomposition of the Mg silicide in the presence of the residual native oxide facilitates silicate formation at 500 °C. Due to the reported thermal stability of Mg silicate it is suggested that this process may be beneficial in modifying the interface char...
http://doras.dcu.ie/15580/
Marked
Mark
High resolution photoemission study of SiOx/Si(111) interface disruption following in situ HfO₂deposition
(2009)
McDonnell, Stephen; Brennan, Barry; Hughes, Greg
High resolution photoemission study of SiOx/Si(111) interface disruption following in situ HfO₂deposition
(2009)
McDonnell, Stephen; Brennan, Barry; Hughes, Greg
Abstract:
We report on an in situ high resolution core level photoemission study of the early stages of interface formation between an ultrathin SiOx layer ( ∼ 0.3 nm) grown on the atomically clean Si(111) surface and a HfO2 dielectric layer. Si 2p core level spectra acquired at 130 eV photon energy reveal evidence of a chemically shifted component on the lower binding energy side of the substrate peak which is attributed to interface defect states resulting from the incorporation of silicon atoms from the substrate into the interfacial oxide at room temperature. This evidence of Si/SiOx interface disruption would be expected to increase charge carrier scattering mechanisms in the silicon and contribute to the generally observed mobility degradation in high-k stacks with ultrathin silicon oxide interface layers.
http://doras.dcu.ie/15581/
Marked
Mark
Atomic resolved material displacement on graphite surfaces by scanning tunnelling microscopy
(1992)
Moriarty, Philip; Hughes, Greg
Atomic resolved material displacement on graphite surfaces by scanning tunnelling microscopy
(1992)
Moriarty, Philip; Hughes, Greg
Abstract:
Atomic scale modifications and subsequent atomic resolution imaging has been achieved on the highly oriented pyrolytic graphite surface in air. Application of short pulse voltages, above a minimum threshold voltage of 3.5 V, across the tunneling gap results in the displacement of a layer or more of atoms to form a hole and create a neighboring mound or ‘‘nanodot’’ from the displaced atoms. We have found a correlation between the hole and ‘‘nanodot’’ volume at the atomic level and observe an asymmetric displacement of material in all cases of feature creation. Nanofeatures as small as four carbon atoms at beta sites have been created. Our experimental observations are consistent with the modification process depending on the gradient in the electric field induced by the rise time of the bias pulse voltage and not the pulse duration. Interesting faceting behavior has also been observed around some hole edges. Tip bias pulsing sometimes induced a tip, and not a surface modification, re...
http://doras.dcu.ie/15582/
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