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M. Schulz - One of the best experts on this subject based on the ideXlab platform.
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Random telegraph signal: An atomic probe of the local current in field-effect transistors
Journal of Applied Physics, 1998Co-Authors: H. H. Mueller, M. SchulzAbstract:The switching amplitude of random telegraph signals (RTSs) caused by trapping a single electron at an Individual Interface defect is studied in sub-μm-sized metal oxide field-effect transistors (MOSFETs). The amplitudes of RTSs depend on the channel nonuniformity and, in particular, on the current distribution in the immediate vicinity of the trap. We find that to a good approximation the RTS amplitude is proportional to the square of the local current density. This mathematical relation is tested and verified with the help of a computer simulation. RTS amplitudes may thus be used as atomic probes of the local current density. By the evaluation of 187 RTS amplitudes in different MOSFETs of the same type, we deduce for the first time a histogram showing the magnitude distribution of the local current density in such devices.
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Individual Interface traps and telegraph noise
The Kluwer International Series in Engineering and Computer Science, 1996Co-Authors: H. H. Mueller, M. SchulzAbstract:The immense progress in silicon technology and miniaturization of electronic devices to sub-micrometer sizes has led to almost defect-free metal oxide semiconductor field effect transistors (MOSFETs). The centerpiece of microelectronics technology, the Si — SiO2 Interface, is today fabricated with an Interface trap density Dit = 108 − 1010 cm-2eV-1, so that a standard MOSFET with sub-μm gate dimensions contains less than 1–100 defects in its active area. A schematic of an n-channel MOSFET is depicted in Figure 5.1(a). The carrier densities induced in the channel by the variable gate bias voltage range from ns = 109 cm-2 in the sub-threshold bias region up to ns = 1012 cm-2 for high gate bias voltages. The number of charge carriers in the channel of a micrometer-sized MOSFET therefore ranges from about 10 in the sub-threshold region up to more than 10000 electrons in strong inversion. Capture of a single electron into an Interface trap causes a noticeable 0.01% to 10% change in the number of mobile charge carriers in the channel and thus in its conductance. Conductance changes of the channel may be even larger, because the mobility is also affected by the trapping or emission of a charge carrier due to the creation or annihilation of a scattering center. Trapping and re-emission of single electrons from and to the channel by Interface traps cause a random switching of the source-drain conductance between two discrete states, as schematically sketched out in Figure 5.1(b).
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Individual Interface traps at the Si—SiO_2 Interface
Journal of Materials Science: Materials in Electronics, 1995Co-Authors: H. H. Mueller, M. SchulzAbstract:In submicrometre-sized metal-oxide-semiconductor field-effect transistors, MOSFETs, the alternate capture and emission of carriers at Individual Si—SiO_2 Interface defects generates discrete switching in the source-drain resistance. The resistance changes are observed in the drain current as random telegraph signals (RTSs) or as stepped transients after a strong perturbation of the trap occupation. The study of Individual defects in MOSFETs has provided a powerful means of investigating the capture and emission kinetics of Interface traps, it has demonstrated the defect origins of low-frequency (1/ f ) noise in MOSFETs, and it has provided new insight into the nature of defects at the Si—SiO_2 Interface. The analysis of Individual Interface defects has shown that a Coulomb energy of several hundred millivolts is involved in the transfer and localization of the single charge carrier into the Interface trap.
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Evaluation of the Coulomb energy for single‐electron Interface trapping in sub‐μm metal‐oxide‐semiconductor field‐effect transistors
Journal of Applied Physics, 1994Co-Authors: H. H. Mueller, D. Wörle, M. SchulzAbstract:Capture and emission time constants are measured for a set of Individual Interface traps in different metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) by random telegraph signals. The data are evaluated to extract the Coulomb energy induced by the transfer of a single electron into an Interface trap. A unified Coulomb energy of the order of several hundred millivolts independent of trap‐specific properties is found, which is proportional to temperature and decays logarithmically with inversion carrier density in the MOSFET channel. The Coulomb energy found is in quantitative agreement with the theoretical modeling. The Coulomb effect is large compared to the trap lowering by the electric field and to the residual entropy change.
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Coulomb energy of traps in semiconductor space‐charge regions
Journal of Applied Physics, 1993Co-Authors: M. SchulzAbstract:Large Coulomb barriers exceeding ΔE≊250 meV are estimated for capture and emission rates of trap centers in semiconductor space‐charge regions. Depending on the charge state of the trap, the capture rate or both the capture and emission rates are activated or deactivated, respectively. The Coulomb energy raises the equilibrium energy state of a trap center that is repulsively charged when occupied. Quantitative agreement of the calculated Coulomb energy is obtained with trapping rates for single Individual Interface traps in metal‐oxide‐semiconductor (MOS) structures measured by random telegraph signals. The Coulomb barrier is reduced in MOS capacitors by partial screening due to mobile charge carriers in the inversion channel. The Coulomb energy can be externally controlled in MOS structures by the gate bias voltage.
N. S. Saks - One of the best experts on this subject based on the ideXlab platform.
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measurement of single Interface trap capture cross sections with charge pumping
Applied Physics Letters, 1997Co-Authors: N. S. SaksAbstract:A technique has been developed using charge pumping to determine electron and hole capture cross sections of Individual Interface traps in small silicon metal–oxide–semiconductor transistors. Values for both cross sections are ≈10−16 cm2 for the particular trap measured.
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Characterization of Individual Interface traps with charge pumping
Applied Physics Letters, 1996Co-Authors: N. S. Saks, Guido Groeseneken, I. DewolfAbstract:Charge pumping (CP) of Individual Interface traps has been studied in small field effect transistors. The amplitude of the CP current is found to be quantized in units of qf, where f is the frequency of the applied CP wave form, and each unit represents the response of a single trap. The time dependence for emission of a trapped electron from a single Interface trap has also been measured with CP. The emission probability is found to increase exponentially with time, consistent with Shockley–Read–Hall statistics. We also compare the relative merits of random telegraph noise experiments and CP for characterizing Individual Interface traps.
H. H. Mueller - One of the best experts on this subject based on the ideXlab platform.
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Random telegraph signal: An atomic probe of the local current in field-effect transistors
Journal of Applied Physics, 1998Co-Authors: H. H. Mueller, M. SchulzAbstract:The switching amplitude of random telegraph signals (RTSs) caused by trapping a single electron at an Individual Interface defect is studied in sub-μm-sized metal oxide field-effect transistors (MOSFETs). The amplitudes of RTSs depend on the channel nonuniformity and, in particular, on the current distribution in the immediate vicinity of the trap. We find that to a good approximation the RTS amplitude is proportional to the square of the local current density. This mathematical relation is tested and verified with the help of a computer simulation. RTS amplitudes may thus be used as atomic probes of the local current density. By the evaluation of 187 RTS amplitudes in different MOSFETs of the same type, we deduce for the first time a histogram showing the magnitude distribution of the local current density in such devices.
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Individual Interface traps and telegraph noise
The Kluwer International Series in Engineering and Computer Science, 1996Co-Authors: H. H. Mueller, M. SchulzAbstract:The immense progress in silicon technology and miniaturization of electronic devices to sub-micrometer sizes has led to almost defect-free metal oxide semiconductor field effect transistors (MOSFETs). The centerpiece of microelectronics technology, the Si — SiO2 Interface, is today fabricated with an Interface trap density Dit = 108 − 1010 cm-2eV-1, so that a standard MOSFET with sub-μm gate dimensions contains less than 1–100 defects in its active area. A schematic of an n-channel MOSFET is depicted in Figure 5.1(a). The carrier densities induced in the channel by the variable gate bias voltage range from ns = 109 cm-2 in the sub-threshold bias region up to ns = 1012 cm-2 for high gate bias voltages. The number of charge carriers in the channel of a micrometer-sized MOSFET therefore ranges from about 10 in the sub-threshold region up to more than 10000 electrons in strong inversion. Capture of a single electron into an Interface trap causes a noticeable 0.01% to 10% change in the number of mobile charge carriers in the channel and thus in its conductance. Conductance changes of the channel may be even larger, because the mobility is also affected by the trapping or emission of a charge carrier due to the creation or annihilation of a scattering center. Trapping and re-emission of single electrons from and to the channel by Interface traps cause a random switching of the source-drain conductance between two discrete states, as schematically sketched out in Figure 5.1(b).
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Individual Interface traps at the Si—SiO_2 Interface
Journal of Materials Science: Materials in Electronics, 1995Co-Authors: H. H. Mueller, M. SchulzAbstract:In submicrometre-sized metal-oxide-semiconductor field-effect transistors, MOSFETs, the alternate capture and emission of carriers at Individual Si—SiO_2 Interface defects generates discrete switching in the source-drain resistance. The resistance changes are observed in the drain current as random telegraph signals (RTSs) or as stepped transients after a strong perturbation of the trap occupation. The study of Individual defects in MOSFETs has provided a powerful means of investigating the capture and emission kinetics of Interface traps, it has demonstrated the defect origins of low-frequency (1/ f ) noise in MOSFETs, and it has provided new insight into the nature of defects at the Si—SiO_2 Interface. The analysis of Individual Interface defects has shown that a Coulomb energy of several hundred millivolts is involved in the transfer and localization of the single charge carrier into the Interface trap.
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Evaluation of the Coulomb energy for single‐electron Interface trapping in sub‐μm metal‐oxide‐semiconductor field‐effect transistors
Journal of Applied Physics, 1994Co-Authors: H. H. Mueller, D. Wörle, M. SchulzAbstract:Capture and emission time constants are measured for a set of Individual Interface traps in different metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) by random telegraph signals. The data are evaluated to extract the Coulomb energy induced by the transfer of a single electron into an Interface trap. A unified Coulomb energy of the order of several hundred millivolts independent of trap‐specific properties is found, which is proportional to temperature and decays logarithmically with inversion carrier density in the MOSFET channel. The Coulomb energy found is in quantitative agreement with the theoretical modeling. The Coulomb effect is large compared to the trap lowering by the electric field and to the residual entropy change.
Khosro Sadeghniiat - One of the best experts on this subject based on the ideXlab platform.
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Assessment of the psychosocial work environment of professional drivers
Journal of Public Health, 2015Co-Authors: Omid Aminian, Sahar Eftekhari, Mostafa Ghaffari, Zeinab Moinfar, Farzaneh Mirzaaghaee, Khosro SadeghniiatAbstract:Aim Along with globalization in recent periods, psychosocial risks at the workplace have been classified as considerable developing risks for human mental and physical health. These risks exist both in developed and developing countries. The current study aims to assess the psychosocial work environment of professional drivers in a multidimensional concept. Subject and methods The study population consisted of 645 Iranian professional drivers. Psychosocial factors were examined in five domains including job demand, job content, interpersonal relationship, work–Individual Interface and general and mental health through the validated Persian medium-size version of the Copenhagen Psychosocial Questionnaire (COPSOQ). Results Among 26 psychosocial scales, sensory demands (91.3) and cognitive demands (70.3) got the highest average scores in professional drivers. Logistic regression was applied to evaluate the association between psychosocial work environment indexes and self reported health and well being of drivers. This study showed that poor psychosocial work environment in job demand, job content, work–Individual Interface as well as having a car accident history was associated with unfavorable health outcomes for the participants, after adjustment for age, marital status, education level, vehicle type and smoking. Conclusion It is worth focusing on drivers’ working schedule and their psychosocial work environment.
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Assessment of the psychosocial work environment of professional drivers
Journal of Public Health, 2015Co-Authors: Omid Aminian, Sahar Eftekhari, Mostafa Ghaffari, Zeinab Moinfar, Farzaneh Mirzaaghaee, Khosro SadeghniiatAbstract:Along with globalization in recent periods, psychosocial risks at the workplace have been classified as considerable developing risks for human mental and physical health. These risks exist both in developed and developing countries. The current study aims to assess the psychosocial work environment of professional drivers in a multidimensional concept. The study population consisted of 645 Iranian professional drivers. Psychosocial factors were examined in five domains including job demand, job content, interpersonal relationship, work–Individual Interface and general and mental health through the validated Persian medium-size version of the Copenhagen Psychosocial Questionnaire (COPSOQ). Among 26 psychosocial scales, sensory demands (91.3) and cognitive demands (70.3) got the highest average scores in professional drivers. Logistic regression was applied to evaluate the association between psychosocial work environment indexes and self reported health and well being of drivers. This study showed that poor psychosocial work environment in job demand, job content, work–Individual Interface as well as having a car accident history was associated with unfavorable health outcomes for the participants, after adjustment for age, marital status, education level, vehicle type and smoking. It is worth focusing on drivers’ working schedule and their psychosocial work environment.
Pinak Chakrabarti - One of the best experts on this subject based on the ideXlab platform.
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Empirical estimation of the energetic contribution of Individual Interface residues in structures of protein–protein complexes
Journal of Computer-Aided Molecular Design, 2009Co-Authors: Mainak Guharoy, Pinak ChakrabartiAbstract:We report a simple algorithm to scan Interfaces in protein–protein complexes for identifying binding ‘hot spots’. The change in side-chain solvent accessible area (ΔASA) of Interface residues has been related to change in binding energy due to mutating Interface residues to Ala (ΔΔ G _X → ALA) based on two criteria—hydrogen bonding across the Interface and location in the Interface core—both of which are major determinants in specific, high-affinity binding. These relationships are used to predict the energetic contribution of Individual Interface residues. The predictions are tested against 462 experimental X → ALA mutations from 28 Interfaces with an average unsigned error of 1.04 kcal/mol. More than 80% of Interface hot spots (with experimental ΔΔ G ≥ 2 kcal/mol) could be identified as being energetically important. From the experimental values, Asp, Lys, Tyr and Trp are found to contribute most of the binding energy, burying >45 Å^2 on average. The method described here would be useful to understand and interfere with protein interactions by assessing the energetic importance of Individual Interface residues.
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Empirical estimation of the energetic contribution of Individual Interface residues in structures of protein-protein complexes.
Journal of computer-aided molecular design, 2009Co-Authors: Mainak Guharoy, Pinak ChakrabartiAbstract:We report a simple algorithm to scan Interfaces in protein–protein complexes for identifying binding ‘hot spots’. The change in side-chain solvent accessible area (ΔASA) of Interface residues has been related to change in binding energy due to mutating Interface residues to Ala (ΔΔG X → ALA) based on two criteria—hydrogen bonding across the Interface and location in the Interface core—both of which are major determinants in specific, high-affinity binding. These relationships are used to predict the energetic contribution of Individual Interface residues. The predictions are tested against 462 experimental X → ALA mutations from 28 Interfaces with an average unsigned error of 1.04 kcal/mol. More than 80% of Interface hot spots (with experimental ΔΔG ≥ 2 kcal/mol) could be identified as being energetically important. From the experimental values, Asp, Lys, Tyr and Trp are found to contribute most of the binding energy, burying >45 A2 on average. The method described here would be useful to understand and interfere with protein interactions by assessing the energetic importance of Individual Interface residues.