Roza Kotlyar - Academia.edu (original) (raw)
Papers by Roza Kotlyar
2012 International Electron Devices Meeting, 2012
ABSTRACT For the past 40 years, relentless focus on Moore's Law transistor scaling has de... more ABSTRACT For the past 40 years, relentless focus on Moore's Law transistor scaling has delivered ever-improving CMOS transistor density. This paper discusses architectural and materials options which will contribute to the ultimate CMOS device. In addition, the paper reviews device options beyond the ultimate CMOS device.
In this paper, we present extensive breakdown results on our 45nm HK+MG technology. Polarity depe... more In this paper, we present extensive breakdown results on our 45nm HK+MG technology. Polarity dependent breakdown and SILC degradation mechanisms have been identified and are attributed gate and substrate injection effects. Processing conditions were optimized to achieve comparable TDDB lifetimes on HK+MG structures at 30% higher E-fields than SiON with a reduction in SILC growth. Extensive long-term stress data collection results and a change in voltage acceleration are reported.
Physical Review E, 1996
Dynamical scaling behavior of the kinetic roughening phenomena in (1+1)- and (2+1)-dimensional mo... more Dynamical scaling behavior of the kinetic roughening phenomena in (1+1)- and (2+1)-dimensional models of molecular beam epitaxy (MBE) is studied using kinetic Monte Carlo simulations mostly within the solid-on-solid lattice gas approximation. We relate the simulation results of our finite temperature stochastic Monte Carlo algorithm, which employs local-configuration-dependent thermally activated Arrhenius diffusion, to those obtained from simpler manifestly nonequilibrium dynamical
Physical Review E, 1994
ABSTRACT
Physical Review B, 1998
The ground state persistent current and electron addition spectrum in two-dimensional quantum dot... more The ground state persistent current and electron addition spectrum in two-dimensional quantum dot arrays and one-dimensional quantum dot rings, pierced by an external magnetic flux, are investigated using the extended Hubbard model. The collective multidot problem is shown to map exactly into the strong field noninteracting finite-size Hofstadter butterfly problem at the spin polarization transition. The finite size Hofstadter problem is discussed, and an analytical solution for limiting values of flux is obtained. In weak fields we predict novel flux periodic oscillations in the spin component along the quantization axis with a periodicity given by nuh/e\nu h/enuh/e ($\nu \le 1$). The sensitivity of the calculated persistent current to interaction and disorder is shown to reflect the intricacies of various Mott-Hubbard quantum phase transitions in two- dimensional systems: the persistent current is suppressed in the antiferromagnetic Mott-insulating phase governed by intradot Coulomb interactions; the persistent current is maximized at the spin density wave - charge density wave transition driven by the nearest neighbor interdot interaction; the Mott-insulating phase persistent current is enhanced by the long-range interdot interactions to its noninteracting value; the strong suppression of the noninteracting current in the presence of random disorder is seen only at large disorder strengths; at half filling even a relatively weak intradot Coulomb interaction enhances the disordered noninteracting system persistent current; in general, the suppression of the persistent current by disorder is less significant in the presence of the long-range interdot Coulomb interaction.
Physical Review B, 1998
ABSTRACT
Physical Review Letters, 2001
We investigate, by numerically calculating the charge stiffness, the effects of random diagonal d... more We investigate, by numerically calculating the charge stiffness, the effects of random diagonal disorder and electron-electron interaction on the nature of the ground state in the 2D Hubbard model through the finite size exact diagonalization technique. By comparing with the corresponding 1D Hubbard model results and by using heuristic arguments we conclude that it is \QTR{it}{unlikely} that there is a 2D metal-insulator quantum phase transition although the effect of interaction in some range of parameters is to substantially enhance the non-interacting charge stiffness.
Physical Review E, 1996
We show that nonlinear interface growth models with roughness exponent αâ¥1 have intrinsic nonpe... more We show that nonlinear interface growth models with roughness exponent αâ¥1 have intrinsic nonperturbative infrared singularities which are inaccessible to the usual dynamical renormalization group analysis. We argue that these infrared singularities give rise to a strong-coupling problem in 1+1 dimensions and provide the underlying reason for the difference between local and global dynamic scaling in these models. {copyright} {ital
Physical Review B, 1998
Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coup... more Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coupled to external gates, is investigated using the Bethe ansatz for a symmetrically biased Hubbard chain. Charge polarization in this correlated system is shown to proceed via two distinct processes: formation of bound states in the metallic phase, and charge-transfer processes corresponding to a superposition of antibound states at opposite ends of the chain in the Mott-insulating phase. The polarizability in the insulating phase of the chain exhibits a universal scaling behavior, while the polarization charge in the metallic phase of the model is shown to be quantized in units of e/2.
Physical Review B, 2004
... LM Woods, TL Reinecke, and Y. Lyanda-Geller, Phys. Rev. B 66, 161318 (2002). IA Merkulov, Al.... more ... LM Woods, TL Reinecke, and Y. Lyanda-Geller, Phys. Rev. B 66, 161318 (2002). IA Merkulov, Al.L. Efros, and M. Rosen, Phys. Rev. ... 2 LM Woods, TL Reinecke, and Y. Lyanda-Geller, Phys. Rev. B 66, 161318 2002 . 3 IA Merkulov, Al.L. Efros, and M. Rosen, Phys. Rev. ...
Physical Review B, 2001
A systematic theoretical and experimental study of Zeeman spin splittings and g factors in semico... more A systematic theoretical and experimental study of Zeeman spin splittings and g factors in semiconductor nanostructures is given. Six-band effective-mass calculations of electron, hole, and exciton spin splittings are made and are shown to account for experimental results presented here on In 0.10 Ga 0.90 As/GaAs systems for the size dependences of g factors in deep-etched quantum dots and wires and for the magnetic-field dependences of the Zeeman splittings in quantum wells. These effects are traced to band mixing, and an analytic form of the results is given that connects these two effects and describes their dependences on dimensionality.
We integrate a strained Si channel with HfO/sub 2/ dielectric and TiN metal gate electrode to dem... more We integrate a strained Si channel with HfO/sub 2/ dielectric and TiN metal gate electrode to demonstrate NMOS transistors with electron mobility better than the universal mobility curve for SiO/sub 2/, inversion equivalent oxide thickness of 1.4 nm (EOT=1 nm), and with three orders of magnitude reduction in gate leakage. To understand the physical mechanism that improves the inversion electron mobility at the HfO/sub 2//strained Si interface, we measure mobility at various temperatures and extract the various scattering components.
Journal of Computational Electronics, 2009
We review our novel simulation approach to model the effects of applied stress and wafer orientat... more We review our novel simulation approach to model the effects of applied stress and wafer orientation by mapping detailed dependencies of long channel physics onto short channel device conditions in Silicon NMOS and PMOS. We use kp and Monte Carlo methods to show the long channel dependencies of these effects on gate fields, doping levels, extrinsic charges, and homogeneous driving fields. Our model predicts the reduced effect of wafer orientation on short channel linear and saturation current drives due to weak gate confinement, high carrier density, high stress, and high driving field prevalent in scaled devices. This reduces NMOS (110) wafer orientation loss compared to (100), while keeping PMOS (110) gains over (100) surface orientation in current drives in 〈110〉 channels, consistent with data.
For the first time, the performance impact of (110) silicon substrates on high-k + metal gate str... more For the first time, the performance impact of (110) silicon substrates on high-k + metal gate strained 45 nm node NMOS and PMOS devices is presented. Record PMOS drive currents of 1.2 mA/um at 1.0 V and 100 nA/um Ioff are reported. It will be demonstrated that 2D short channel effects strongly mitigate the negative impact of (110) substrates on NMOS performance. Narrow width (110) device performance is shown and compared to (100) for the first time. Device reliability is also reported showing no fundamental issue for (110) substrates.
This paper presents an integrated approach to modeling front end stress which has been used to in... more This paper presents an integrated approach to modeling front end stress which has been used to investigate the main sources of stress in advanced logic technologies and how they can be used to improve device performance. The approach is illustrated with the evaluation of several technologically important stress options.
Applied Physics Letters, 2006
... B. Obradovic, R. Kotlyar, F. Heinz, P. Matagne, T. Rakshit, MD Giles, MA Stettler, DE Nikonov... more ... B. Obradovic, R. Kotlyar, F. Heinz, P. Matagne, T. Rakshit, MD Giles, MA Stettler, DE Nikonov. Abstract. ... 108, 19912 (2004). K.Nakada, M.Fujita, G.Dresselhaus, and M.Dresselhaus, Edge state in graphene ribbons: Nanometer size effect and edge shape dependence, Phys. Rev. ...
IEEE Transactions on Electron Devices, 2011
Moore's law technology scaling has improved performance by five orders of magnitude in the last f... more Moore's law technology scaling has improved performance by five orders of magnitude in the last four decades. As advanced technologies continue the pursuit of Moore's law, a variety of challenges will need to be overcome. One of these challenges is the management of process variation. This paper discusses the importance of process variation in modern transistor technology, reviews front-end variation sources, presents device and circuit variation measurement techniques, including circuit and memory data from the 32-nm node, and compares recent intrinsic transistor variation performance from the literature.
The electronic and vibrational properties of carbon nanoribbons (CNRs) are analyzed and compared ... more The electronic and vibrational properties of carbon nanoribbons (CNRs) are analyzed and compared to carbon nanotubes (CNTs). Transport properties are analyzed from the perspective of use in an FET device. The required sizing and consequent processing requirements are discussed. The overall properties of the CNRs and CNTs are found to be similar, with the primary difference being the more restrictive size vs. bandgap behavior of the CNRs
In this work, non-planar, multi-gate InGaAs quantum well field effect transistors (QWFETs) with h... more In this work, non-planar, multi-gate InGaAs quantum well field effect transistors (QWFETs) with high-K gate dielectric and ultra-scaled gate-to-drain and gate-to-source separations (LSIDE) of 5nm are reported for the first time. The high-K gate dielectric formed on this non-planar device structure has the expected thin TOXE of 20.5Å with low JG, and high quality gate dielectric interface. The simplified S/D scheme is needed for the non-planar architecture while achieving significant reduction in parasitic resistance. Compared to the planar high-K InGaAs QWFET with similar TOXE, the non-planar, multi-gate InGaAs QWFET shows significantly improved electrostatics due to better gate control. The results of this work show that non-planar, multi-gate device architecture is an effective way to improve the scalability of III-V QWFETs for low power logic applications.
Applied Physics Letters, 2004
Recent attention has been given to metal-oxide-semiconductor field-effect transistor (MOSFET) dev... more Recent attention has been given to metal-oxide-semiconductor field-effect transistor (MOSFET) device designs that utilize stress to achieve performance gain in both n-type MOSFETs (NMOS) and p-type MOSFETs (PMOS). The physics behind NMOS gain is better understood than that of PMOS gain, which has received less attention. In this letter, we describe the warping phenomena which is responsible for the gain seen in [110] uniaxially stressed PMOS devices on [100] orientated wafers. We also demonstrate that shear uniaxial stress in PMOS is better suited to MOSFET applications than biaxial stress as it is able to maintain gain at high vertical and lateral fields.
2012 International Electron Devices Meeting, 2012
ABSTRACT For the past 40 years, relentless focus on Moore's Law transistor scaling has de... more ABSTRACT For the past 40 years, relentless focus on Moore's Law transistor scaling has delivered ever-improving CMOS transistor density. This paper discusses architectural and materials options which will contribute to the ultimate CMOS device. In addition, the paper reviews device options beyond the ultimate CMOS device.
In this paper, we present extensive breakdown results on our 45nm HK+MG technology. Polarity depe... more In this paper, we present extensive breakdown results on our 45nm HK+MG technology. Polarity dependent breakdown and SILC degradation mechanisms have been identified and are attributed gate and substrate injection effects. Processing conditions were optimized to achieve comparable TDDB lifetimes on HK+MG structures at 30% higher E-fields than SiON with a reduction in SILC growth. Extensive long-term stress data collection results and a change in voltage acceleration are reported.
Physical Review E, 1996
Dynamical scaling behavior of the kinetic roughening phenomena in (1+1)- and (2+1)-dimensional mo... more Dynamical scaling behavior of the kinetic roughening phenomena in (1+1)- and (2+1)-dimensional models of molecular beam epitaxy (MBE) is studied using kinetic Monte Carlo simulations mostly within the solid-on-solid lattice gas approximation. We relate the simulation results of our finite temperature stochastic Monte Carlo algorithm, which employs local-configuration-dependent thermally activated Arrhenius diffusion, to those obtained from simpler manifestly nonequilibrium dynamical
Physical Review E, 1994
ABSTRACT
Physical Review B, 1998
The ground state persistent current and electron addition spectrum in two-dimensional quantum dot... more The ground state persistent current and electron addition spectrum in two-dimensional quantum dot arrays and one-dimensional quantum dot rings, pierced by an external magnetic flux, are investigated using the extended Hubbard model. The collective multidot problem is shown to map exactly into the strong field noninteracting finite-size Hofstadter butterfly problem at the spin polarization transition. The finite size Hofstadter problem is discussed, and an analytical solution for limiting values of flux is obtained. In weak fields we predict novel flux periodic oscillations in the spin component along the quantization axis with a periodicity given by nuh/e\nu h/enuh/e ($\nu \le 1$). The sensitivity of the calculated persistent current to interaction and disorder is shown to reflect the intricacies of various Mott-Hubbard quantum phase transitions in two- dimensional systems: the persistent current is suppressed in the antiferromagnetic Mott-insulating phase governed by intradot Coulomb interactions; the persistent current is maximized at the spin density wave - charge density wave transition driven by the nearest neighbor interdot interaction; the Mott-insulating phase persistent current is enhanced by the long-range interdot interactions to its noninteracting value; the strong suppression of the noninteracting current in the presence of random disorder is seen only at large disorder strengths; at half filling even a relatively weak intradot Coulomb interaction enhances the disordered noninteracting system persistent current; in general, the suppression of the persistent current by disorder is less significant in the presence of the long-range interdot Coulomb interaction.
Physical Review B, 1998
ABSTRACT
Physical Review Letters, 2001
We investigate, by numerically calculating the charge stiffness, the effects of random diagonal d... more We investigate, by numerically calculating the charge stiffness, the effects of random diagonal disorder and electron-electron interaction on the nature of the ground state in the 2D Hubbard model through the finite size exact diagonalization technique. By comparing with the corresponding 1D Hubbard model results and by using heuristic arguments we conclude that it is \QTR{it}{unlikely} that there is a 2D metal-insulator quantum phase transition although the effect of interaction in some range of parameters is to substantially enhance the non-interacting charge stiffness.
Physical Review E, 1996
We show that nonlinear interface growth models with roughness exponent αâ¥1 have intrinsic nonpe... more We show that nonlinear interface growth models with roughness exponent αâ¥1 have intrinsic nonperturbative infrared singularities which are inaccessible to the usual dynamical renormalization group analysis. We argue that these infrared singularities give rise to a strong-coupling problem in 1+1 dimensions and provide the underlying reason for the difference between local and global dynamic scaling in these models. {copyright} {ital
Physical Review B, 1998
Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coup... more Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coupled to external gates, is investigated using the Bethe ansatz for a symmetrically biased Hubbard chain. Charge polarization in this correlated system is shown to proceed via two distinct processes: formation of bound states in the metallic phase, and charge-transfer processes corresponding to a superposition of antibound states at opposite ends of the chain in the Mott-insulating phase. The polarizability in the insulating phase of the chain exhibits a universal scaling behavior, while the polarization charge in the metallic phase of the model is shown to be quantized in units of e/2.
Physical Review B, 2004
... LM Woods, TL Reinecke, and Y. Lyanda-Geller, Phys. Rev. B 66, 161318 (2002). IA Merkulov, Al.... more ... LM Woods, TL Reinecke, and Y. Lyanda-Geller, Phys. Rev. B 66, 161318 (2002). IA Merkulov, Al.L. Efros, and M. Rosen, Phys. Rev. ... 2 LM Woods, TL Reinecke, and Y. Lyanda-Geller, Phys. Rev. B 66, 161318 2002 . 3 IA Merkulov, Al.L. Efros, and M. Rosen, Phys. Rev. ...
Physical Review B, 2001
A systematic theoretical and experimental study of Zeeman spin splittings and g factors in semico... more A systematic theoretical and experimental study of Zeeman spin splittings and g factors in semiconductor nanostructures is given. Six-band effective-mass calculations of electron, hole, and exciton spin splittings are made and are shown to account for experimental results presented here on In 0.10 Ga 0.90 As/GaAs systems for the size dependences of g factors in deep-etched quantum dots and wires and for the magnetic-field dependences of the Zeeman splittings in quantum wells. These effects are traced to band mixing, and an analytic form of the results is given that connects these two effects and describes their dependences on dimensionality.
We integrate a strained Si channel with HfO/sub 2/ dielectric and TiN metal gate electrode to dem... more We integrate a strained Si channel with HfO/sub 2/ dielectric and TiN metal gate electrode to demonstrate NMOS transistors with electron mobility better than the universal mobility curve for SiO/sub 2/, inversion equivalent oxide thickness of 1.4 nm (EOT=1 nm), and with three orders of magnitude reduction in gate leakage. To understand the physical mechanism that improves the inversion electron mobility at the HfO/sub 2//strained Si interface, we measure mobility at various temperatures and extract the various scattering components.
Journal of Computational Electronics, 2009
We review our novel simulation approach to model the effects of applied stress and wafer orientat... more We review our novel simulation approach to model the effects of applied stress and wafer orientation by mapping detailed dependencies of long channel physics onto short channel device conditions in Silicon NMOS and PMOS. We use kp and Monte Carlo methods to show the long channel dependencies of these effects on gate fields, doping levels, extrinsic charges, and homogeneous driving fields. Our model predicts the reduced effect of wafer orientation on short channel linear and saturation current drives due to weak gate confinement, high carrier density, high stress, and high driving field prevalent in scaled devices. This reduces NMOS (110) wafer orientation loss compared to (100), while keeping PMOS (110) gains over (100) surface orientation in current drives in 〈110〉 channels, consistent with data.
For the first time, the performance impact of (110) silicon substrates on high-k + metal gate str... more For the first time, the performance impact of (110) silicon substrates on high-k + metal gate strained 45 nm node NMOS and PMOS devices is presented. Record PMOS drive currents of 1.2 mA/um at 1.0 V and 100 nA/um Ioff are reported. It will be demonstrated that 2D short channel effects strongly mitigate the negative impact of (110) substrates on NMOS performance. Narrow width (110) device performance is shown and compared to (100) for the first time. Device reliability is also reported showing no fundamental issue for (110) substrates.
This paper presents an integrated approach to modeling front end stress which has been used to in... more This paper presents an integrated approach to modeling front end stress which has been used to investigate the main sources of stress in advanced logic technologies and how they can be used to improve device performance. The approach is illustrated with the evaluation of several technologically important stress options.
Applied Physics Letters, 2006
... B. Obradovic, R. Kotlyar, F. Heinz, P. Matagne, T. Rakshit, MD Giles, MA Stettler, DE Nikonov... more ... B. Obradovic, R. Kotlyar, F. Heinz, P. Matagne, T. Rakshit, MD Giles, MA Stettler, DE Nikonov. Abstract. ... 108, 19912 (2004). K.Nakada, M.Fujita, G.Dresselhaus, and M.Dresselhaus, Edge state in graphene ribbons: Nanometer size effect and edge shape dependence, Phys. Rev. ...
IEEE Transactions on Electron Devices, 2011
Moore's law technology scaling has improved performance by five orders of magnitude in the last f... more Moore's law technology scaling has improved performance by five orders of magnitude in the last four decades. As advanced technologies continue the pursuit of Moore's law, a variety of challenges will need to be overcome. One of these challenges is the management of process variation. This paper discusses the importance of process variation in modern transistor technology, reviews front-end variation sources, presents device and circuit variation measurement techniques, including circuit and memory data from the 32-nm node, and compares recent intrinsic transistor variation performance from the literature.
The electronic and vibrational properties of carbon nanoribbons (CNRs) are analyzed and compared ... more The electronic and vibrational properties of carbon nanoribbons (CNRs) are analyzed and compared to carbon nanotubes (CNTs). Transport properties are analyzed from the perspective of use in an FET device. The required sizing and consequent processing requirements are discussed. The overall properties of the CNRs and CNTs are found to be similar, with the primary difference being the more restrictive size vs. bandgap behavior of the CNRs
In this work, non-planar, multi-gate InGaAs quantum well field effect transistors (QWFETs) with h... more In this work, non-planar, multi-gate InGaAs quantum well field effect transistors (QWFETs) with high-K gate dielectric and ultra-scaled gate-to-drain and gate-to-source separations (LSIDE) of 5nm are reported for the first time. The high-K gate dielectric formed on this non-planar device structure has the expected thin TOXE of 20.5Å with low JG, and high quality gate dielectric interface. The simplified S/D scheme is needed for the non-planar architecture while achieving significant reduction in parasitic resistance. Compared to the planar high-K InGaAs QWFET with similar TOXE, the non-planar, multi-gate InGaAs QWFET shows significantly improved electrostatics due to better gate control. The results of this work show that non-planar, multi-gate device architecture is an effective way to improve the scalability of III-V QWFETs for low power logic applications.
Applied Physics Letters, 2004
Recent attention has been given to metal-oxide-semiconductor field-effect transistor (MOSFET) dev... more Recent attention has been given to metal-oxide-semiconductor field-effect transistor (MOSFET) device designs that utilize stress to achieve performance gain in both n-type MOSFETs (NMOS) and p-type MOSFETs (PMOS). The physics behind NMOS gain is better understood than that of PMOS gain, which has received less attention. In this letter, we describe the warping phenomena which is responsible for the gain seen in [110] uniaxially stressed PMOS devices on [100] orientated wafers. We also demonstrate that shear uniaxial stress in PMOS is better suited to MOSFET applications than biaxial stress as it is able to maintain gain at high vertical and lateral fields.