Rodolfo Cuerno | Universidad Carlos III de Madrid (original) (raw)
Papers by Rodolfo Cuerno
Low-pressure chemical vapor deposition LPCVD is one of the most frequently used techniques for th... more Low-pressure chemical vapor deposition LPCVD is one of the most frequently used techniques for thin-film production in several industrial applications. 1 Silicon dioxide films have been extensively used in very large scale integrated devices. Knowledge and eventual control of the morphology of silica films produced by CVD become very important as device dimensions are being continuously reduced. In particular, this control becomes critical when conformal growth ie, good step coverage is required.
A new model is introduced for two-dimensional crystalline interfaces with negligible surface tens... more A new model is introduced for two-dimensional crystalline interfaces with negligible surface tension. The model is given by a discrete version of the linear molecular beam epitaxy (MBE) equation plus an additional term periodic in the interface height variable. Langevin dynamics simulations and analytical arguments show that the model exhibits a roughening transition to the high temperature phase of the sine-Gordon model, whose initial stages are nevertheless described by the scaling of the linear MBE equation.
During the last decade, there have been great theoretical and experimental efforts to understand ... more During the last decade, there have been great theoretical and experimental efforts to understand surface growth. This is due to possible applications, eg, to the production of thin films and, from the basic point of view, to the interesting examples growing surfaces provide of nonequilibrium statistical systems 1, in some cases with strong relation to relevant equilibrium systems 2.
The dynamics of growing surfaces 1, 2 has attracted great interest during the last decade. This i... more The dynamics of growing surfaces 1, 2 has attracted great interest during the last decade. This is due both to the practical implications for the control of film quality in thin film production techniques, and to the fundamental questions it raises in areas of physics such as spatially extended systems in the presence of fluctuations 3, or scale invariance in nonequilibrium systems 4.
We study the critical behavior of the Laplacian roughening model, which describes the growth of t... more We study the critical behavior of the Laplacian roughening model, which describes the growth of tensionless surfaces. This type of growth phenomena is very important, for instance, in biological membranes and in molecular beam epitaxy. We summarize previous analytical and numerical results and point out their contradictions and differences, thus making clear the context of our work.
A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuati... more A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuations of the precursor film observed in spreading experiments. Matter is transported both by holes and particles, and the distribution of each can be described by driven diffusion with a moving boundary. This picture leads to a stochastic partial differential equation for the shape of the boundary. Explicit analytic results are obtained which agree with the simulations of the lattice gas.
We report large scale Monte Carlo simulations of the equilibrium discrete Laplacian roughening dL... more We report large scale Monte Carlo simulations of the equilibrium discrete Laplacian roughening dLr model, originally introduced as the simplest one accommodating the hexatic phase in two-dimensional melting. The dLr model is also relevant to surface roughening in molecular beam epitaxy MBE. Our data suggest a single phase transition, possibly of the Kosterlitz-Thouless type, between a flat low-temperature phase and a rough, tensionless, high-temperature phase.
A lack of universality with respect to ion species has been recently established in nanostructuri... more A lack of universality with respect to ion species has been recently established in nanostructuring of
semiconductor surfaces by low-energy ion-beam bombardment. This variability affects basic properties of the
pattern formation process, like the critical incidence angle for pattern formation, and has remained unaccounted
for. Here, we show that nonuniform generation of stress across the damaged amorphous layer induced by
the irradiation is a key factor behind the range of experimental observations, as the form of the stress field
is controlled by the ion/target combination. This effect acts in synergy with the nontrivial evolution of the
amorphous-crystalline interface. We reach these conclusions by contrasting a multiscale theoretical approach,
which combines molecular dynamics and a continuum viscous flow model, with experiments using Xe + and Ar +
ions on a Si(100) target. Our general approach can apply to a variety of semiconductor systems and conditions.
We study kinetically rough surfaces which display anomalous scaling in local properties such as t... more We study kinetically rough surfaces which display anomalous scaling in local properties such as the rough- ness or the height-difference correlation function. By studying the power spectrum of the surface and its relation to the height-difference correlation, we distinguish two independent causes for anomalous scaling. One is superroughening ~global roughness exponent larger than or equal to 1!, even if the
Physical Review Letters, 2002
A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuati... more A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuations of the precursor film observed in spreading experiments. Matter is transported both by holes and particles, and the distribution of each can be described by driven diffusion with a moving boundary. This picture leads to a stochastic partial differential equation for the shape of the boundary.
Physica A: Statistical Mechanics and its Applications, 2002
Physical review letters, Jan 31, 2014
We study the dynamics of three-dimensional Fisher fronts in the presence of density fluctuations.... more We study the dynamics of three-dimensional Fisher fronts in the presence of density fluctuations. To this end we simulate the Fisher equation subject to stochastic internal noise, and study how the front moves and roughens as a function of the number of particles in the system, N. Our results suggest that the macroscopic behavior of the system is driven by the microscopic dynamics at its leading edge where number fluctuations are dominated by rare events. Contrary to naive expectations, the strength of front fluctuations decays extremely slowly as 1/logN, inducing large-scale fluctuations which we find belong to the one-dimensional Kardar-Parisi-Zhang universality class of kinetically rough interfaces. Hence, we find that there is no weak-noise regime for Fisher fronts, even for realistic numbers of particles in macroscopic systems.
Low-pressure chemical vapor deposition LPCVD is one of the most frequently used techniques for th... more Low-pressure chemical vapor deposition LPCVD is one of the most frequently used techniques for thin-film production in several industrial applications. 1 Silicon dioxide films have been extensively used in very large scale integrated devices. Knowledge and eventual control of the morphology of silica films produced by CVD become very important as device dimensions are being continuously reduced. In particular, this control becomes critical when conformal growth ie, good step coverage is required.
A new model is introduced for two-dimensional crystalline interfaces with negligible surface tens... more A new model is introduced for two-dimensional crystalline interfaces with negligible surface tension. The model is given by a discrete version of the linear molecular beam epitaxy (MBE) equation plus an additional term periodic in the interface height variable. Langevin dynamics simulations and analytical arguments show that the model exhibits a roughening transition to the high temperature phase of the sine-Gordon model, whose initial stages are nevertheless described by the scaling of the linear MBE equation.
During the last decade, there have been great theoretical and experimental efforts to understand ... more During the last decade, there have been great theoretical and experimental efforts to understand surface growth. This is due to possible applications, eg, to the production of thin films and, from the basic point of view, to the interesting examples growing surfaces provide of nonequilibrium statistical systems 1, in some cases with strong relation to relevant equilibrium systems 2.
The dynamics of growing surfaces 1, 2 has attracted great interest during the last decade. This i... more The dynamics of growing surfaces 1, 2 has attracted great interest during the last decade. This is due both to the practical implications for the control of film quality in thin film production techniques, and to the fundamental questions it raises in areas of physics such as spatially extended systems in the presence of fluctuations 3, or scale invariance in nonequilibrium systems 4.
We study the critical behavior of the Laplacian roughening model, which describes the growth of t... more We study the critical behavior of the Laplacian roughening model, which describes the growth of tensionless surfaces. This type of growth phenomena is very important, for instance, in biological membranes and in molecular beam epitaxy. We summarize previous analytical and numerical results and point out their contradictions and differences, thus making clear the context of our work.
A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuati... more A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuations of the precursor film observed in spreading experiments. Matter is transported both by holes and particles, and the distribution of each can be described by driven diffusion with a moving boundary. This picture leads to a stochastic partial differential equation for the shape of the boundary. Explicit analytic results are obtained which agree with the simulations of the lattice gas.
We report large scale Monte Carlo simulations of the equilibrium discrete Laplacian roughening dL... more We report large scale Monte Carlo simulations of the equilibrium discrete Laplacian roughening dLr model, originally introduced as the simplest one accommodating the hexatic phase in two-dimensional melting. The dLr model is also relevant to surface roughening in molecular beam epitaxy MBE. Our data suggest a single phase transition, possibly of the Kosterlitz-Thouless type, between a flat low-temperature phase and a rough, tensionless, high-temperature phase.
A lack of universality with respect to ion species has been recently established in nanostructuri... more A lack of universality with respect to ion species has been recently established in nanostructuring of
semiconductor surfaces by low-energy ion-beam bombardment. This variability affects basic properties of the
pattern formation process, like the critical incidence angle for pattern formation, and has remained unaccounted
for. Here, we show that nonuniform generation of stress across the damaged amorphous layer induced by
the irradiation is a key factor behind the range of experimental observations, as the form of the stress field
is controlled by the ion/target combination. This effect acts in synergy with the nontrivial evolution of the
amorphous-crystalline interface. We reach these conclusions by contrasting a multiscale theoretical approach,
which combines molecular dynamics and a continuum viscous flow model, with experiments using Xe + and Ar +
ions on a Si(100) target. Our general approach can apply to a variety of semiconductor systems and conditions.
We study kinetically rough surfaces which display anomalous scaling in local properties such as t... more We study kinetically rough surfaces which display anomalous scaling in local properties such as the rough- ness or the height-difference correlation function. By studying the power spectrum of the surface and its relation to the height-difference correlation, we distinguish two independent causes for anomalous scaling. One is superroughening ~global roughness exponent larger than or equal to 1!, even if the
Physical Review Letters, 2002
A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuati... more A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuations of the precursor film observed in spreading experiments. Matter is transported both by holes and particles, and the distribution of each can be described by driven diffusion with a moving boundary. This picture leads to a stochastic partial differential equation for the shape of the boundary.
Physica A: Statistical Mechanics and its Applications, 2002
Physical review letters, Jan 31, 2014
We study the dynamics of three-dimensional Fisher fronts in the presence of density fluctuations.... more We study the dynamics of three-dimensional Fisher fronts in the presence of density fluctuations. To this end we simulate the Fisher equation subject to stochastic internal noise, and study how the front moves and roughens as a function of the number of particles in the system, N. Our results suggest that the macroscopic behavior of the system is driven by the microscopic dynamics at its leading edge where number fluctuations are dominated by rare events. Contrary to naive expectations, the strength of front fluctuations decays extremely slowly as 1/logN, inducing large-scale fluctuations which we find belong to the one-dimensional Kardar-Parisi-Zhang universality class of kinetically rough interfaces. Hence, we find that there is no weak-noise regime for Fisher fronts, even for realistic numbers of particles in macroscopic systems.