Devi Dass | University of Jammu, Jammu, Jammu and Kashmir, India (original) (raw)
Papers by Devi Dass
Results in Surfaces and Interfaces
Abstract Surface passivation is one of the best techniques to eliminate the adverse effects of th... more Abstract Surface passivation is one of the best techniques to eliminate the adverse effects of the dangling bonds present in the simple nanostructures and modify their electronic property. In this work, the metallic-to-semiconducting transition of silicon nanowires (SiNWs) by surface passivation has been investigated via sp 3 tight-binding calculation. The results show that without surface passivation the SiNW reveals metallic behavior with either a zero or very small negligible negative band gap since it is due to the fact that the conduction band minimum (CBM) and the valence band maximum (VBM) overlaps at the Fermi level or the CBM cross the Fermi level and located below the VBM. The results further show that when the entire surface dangling bonds are passivated with hydrogen (H) atoms the electronic property of a SiNW has been transformed from metallic to semiconducting with either a direct or indirect band gap depending upon the diameter and the orientation. This observed superior semiconducting property (excellent band gap with direct and indirect nature) with the use of H passivation of surfaces is the clear advantage of an H-passivated SiNW over non-surface passivated SiNW. It is further noted that the -oriented H-passivated SiNW exhibits direct band gap semiconductor behavior due to the reason that the CBM and the VBM are located at the same Γ point within their band structures while all -oriented, -oriented, and -oriented H-passivated SiNWs exhibit indirect band gap semiconductor behavior due to the reason that the CBM located at X point and the VBM located at Γ point within their band structures. Further, the increase band gap of each oriented H-passivated SiNW with decreasing diameter provides clear confirmation of the quantum confinement effect never happens for the case of a non surface passivated SiNW. This is another good advantage of H-passivated SiNW over non-surface passivated SiNW. Finally, it has been observed from these results that the H-passivated SiNWs are best suitable channel materials for designing high performance novel transistors due to their tunable band gap and due to their direct band gap for orientation they are suitable optically active material for photonic applications.
Superlattices and Microstructures, 2018
Graphene nanoribbon (GNR), a new 2D carbon nanomaterial, has some unique features and special pro... more Graphene nanoribbon (GNR), a new 2D carbon nanomaterial, has some unique features and special properties that offer a great potential for interconnect, nanoelectronic devices, optoelectronics, and nanophotonics. This paper reports the structural analysis, electronic properties, and band gaps of a GNR considering different chirality combinations obtained using the p z orbital tight binding model. In structural analysis, the analytical expressions for GNRs have been developed and verified using the simulation for the first time. It has been found that the total number of unit cells and carbon atoms within an overall unit cell and molecular structure of a GNR have been changed with the change in their chirality values which are similar to the values calculated using the developed analytical expressions thus validating both the simulation as well as analytical results. Further, the electronic band structures at different chirality values have been shown for the identification of metallic and semiconductor properties of a GNR. It has been concluded that all zigzag edge GNRs are metallic with very small band gaps range whereas all armchair GNRs show both the metallic and semiconductor nature with very small and high band gaps range. Again, the total number of subbands in each electronic band structure is equal to the total number of carbon atoms present in overall unit cell of the corresponding GNR. The semiconductors GNRs can be used as a channel material in field effect transistor suitable for advanced CMOS technology whereas the metallic GNRs could be used for interconnect.
Superlattices and Microstructures, 2018
Please cite this article as: D. Dass, Structural parameters, electronic properties, and band gaps... more Please cite this article as: D. Dass, Structural parameters, electronic properties, and band gaps of a single walled carbon nanotube: A p z orbital tight binding study,
Applied Surface Science, 2019
Please cite this article as: D. Dass, Effects of surface passivation by hydrogen on the structura... more Please cite this article as: D. Dass, Effects of surface passivation by hydrogen on the structural and electronic properties of a germanium nanowire: A sp3 tight binding study, Applied Surface Science,
Applied Surface Science, 2019
International journal of computational engineering research, Sep 2012
Recently it has been experimentally confirmed that the chirality of a nanotube controls the speed... more Recently it has been experimentally confirmed that the chirality of a nanotube controls the speed of its growth, and the armchair nanotube should grow the fastest. Therefore, chirality is an important parameter in designing a carbon nanotube (CNT) and needs to be investigated for the role it plays in the structure of a CNT. In this paper, we have analytically analyzed the unit cell and molecular structures of various single walled carbon nanotubes (SWCNTs) at different values of chirality combinations. The results suggest that total number of unit cells, carbon atoms and hexagons in each structure of SWCNTs are being changed by changing its chirality. A simple and step by step approach has been followed in describing the analytical expressions of overall unit cell structure, molecular structure, chiral angle and diameter of SWCNTs. The analytical formulations have been verified by simulating different SWCNTs at various chirality values. The simulated results match very well with the mathematical results thus validating, both the simulations as well as analytical expressions.
Journal of Nano-& Electronic Physics, Mar 2013
In this paper, we have studied a double gate nanoscale MOSFET for various channel materials using... more In this paper, we have studied a double gate nanoscale MOSFET for various channel materials using simulation approach. The device metrics considered at the nanometer scale are subthreshold swing (SS), drain induced barrier lowering (DIBL), on and off current, carrier injection velocity (vinj), etc. The channel materials studied are Silicon (Si), Germanium (Ge), Gallium Arsenide (GaAs), Zinc Oxide (ZnO), Zinc Sulfide (ZnS), Indium Arsenide (InAs), Indium Phosphide (InP) and Indium Antimonide (InSb). The results suggest that InSb and InAs materials have highest Ion and lowest Ioff values when used in the channel of the proposed MOSFET. Besides, InSb has the highest values for Ion / Ioff ratio, vinj, transconductance (gm) and improved short channel effects (SS = 59.71 and DIBL = 1.14, both are very close to ideal values). More results such as effect of quantum capacitance verses gate voltage (Vgs), drain current (Ids) vs. gate voltage and drain voltage (Vds), ratio of transconductance (gm) and drain current (Id) vs. gate voltage, average velocity vs. gate voltage and injection velocity (Vinj) for the mentioned channel materials have been investigated. Various results obtained indicate that InSb and InAs as channel material appear to be suitable for high performance logic and even low operating power requirements for future nanoscale devices as suggested by latest ITRS reports.
International Journal on Organic Electronics, Jan 2013
The exponential rise in the density of silicon CMOS transistors has now reached a limit and threa... more The exponential rise in the density of silicon CMOS transistors has now reached a limit and threatening to end the microelectronics revolution. To tackle this difficulty, group III-V compound semiconductors due to their outstanding electron transport properties and high mobility are very actively being researched as channel materials for future highly scaled CMOS devices. In this paper, we have studied a ballistic nanoscale MOSFET using simulation approach by replacing silicon in the channel by III-V compounds. The channel materials considered are silicon (Si), Gallium arsenide (GaAs), Indium arsenide (InAs), Indium Phosphide (InP) and Indium Antimonide (InSb). The device metrics considered at the nanometer scale are subthreshold swing, Drain induced barrier lowering, on and off current, carrier injection velocity and switching speed. These channel materials have been studied using various dielectric constants. It has been observed that Indium Antimonide (InSb) has higher on current, higher transconductance, idealistic subthreshold swing, higher output conductance, higher carrier injection velocity and comparable voltage gain compared to Silicon, thus, making InSb as a possible candidate to be used as channel material in future nanoscale devices.
The African Review of Physics, Feb 1, 2013
Carbon nanotubes are nanomaterials, which can be used in various areas due to their superior elec... more Carbon nanotubes are nanomaterials, which can be used in various areas due to their superior electrical and mechanical properties and has become the most promising candidate for nanoelectronics, nonodevices and nanocomposites. Chirality is an important parameter in designing a carbon nanotube (CNT) and needs to be investigated for the role it plays in the structure of a CNT. Recently it has been experimentally confirmed that the chirality of a nanotube controls the speed of its growth, and the armchair nanotube should grow the fastest. In this paper, we have presented various electrical parameters for an armchair CNT such as potential, electric field, electron current, charge density, I-V characteristics, and resistance variations by adjusting the input parameters such as chirality, length of the CNT, ambient temperature, and applied voltage. It has been observed that with the increase in chirality or chiral values of CNT, the electron current enhances whereas the resistance decrease. The charge density and I-V characteristics can be changed by varying chirality but it does not affect potential and electric field. The paper also highlights the effect of various parameters such as length of armchair CNT, ambient temperature and applied voltage on the performance of armchair CNT.
Journal of Nano-& Electronic Physics, May 4, 2013
As scaling down Si MOSFET devices degrade device performance in terms of short channel effects. C... more As scaling down Si MOSFET devices degrade device performance in terms of short channel effects. Carbon nanotube field effect transistor (CNTFET) is one of the novel nanoelectronics devices that overcome those MOSFET limitations. The carbon nanotube field effect transistors (CNTFETs) have been explored and proposed to be the promising candidate for the next generation of integrated circuit (IC) devices. To explore the role of CNTFETs in future integrated circuits, it is important to evaluate their performance. However, to do that we need a model that can accurately describe the behavior of the CNTFETs so that the design and evaluation of circuits using these devices can be made. In this paper, we have investigated the effect of scaling gate insulator thickness on the device performance of cylindrical shaped ballistic CNTFET in terms of transfer characteristics, output characteristics, average velocity, gm/Id ratio, mobile charge, quantum capacitance/insulator capacitance, drive current (Ion), Ion / Ioff ratio, transconductance, and output conductance. We concluded that the device metrics such as Ion, Ion / Ioff ratio, transconductance, and output conductance increases with the decrease in gate insulator thickness. Also, we concluded that the gate insulator thickness reduction causes subthreshold slope close to the theoretical limit of 60 mV/decade and DIBL close to zero at room temperature.
Results in Surfaces and Interfaces
Abstract Surface passivation is one of the best techniques to eliminate the adverse effects of th... more Abstract Surface passivation is one of the best techniques to eliminate the adverse effects of the dangling bonds present in the simple nanostructures and modify their electronic property. In this work, the metallic-to-semiconducting transition of silicon nanowires (SiNWs) by surface passivation has been investigated via sp 3 tight-binding calculation. The results show that without surface passivation the SiNW reveals metallic behavior with either a zero or very small negligible negative band gap since it is due to the fact that the conduction band minimum (CBM) and the valence band maximum (VBM) overlaps at the Fermi level or the CBM cross the Fermi level and located below the VBM. The results further show that when the entire surface dangling bonds are passivated with hydrogen (H) atoms the electronic property of a SiNW has been transformed from metallic to semiconducting with either a direct or indirect band gap depending upon the diameter and the orientation. This observed superior semiconducting property (excellent band gap with direct and indirect nature) with the use of H passivation of surfaces is the clear advantage of an H-passivated SiNW over non-surface passivated SiNW. It is further noted that the -oriented H-passivated SiNW exhibits direct band gap semiconductor behavior due to the reason that the CBM and the VBM are located at the same Γ point within their band structures while all -oriented, -oriented, and -oriented H-passivated SiNWs exhibit indirect band gap semiconductor behavior due to the reason that the CBM located at X point and the VBM located at Γ point within their band structures. Further, the increase band gap of each oriented H-passivated SiNW with decreasing diameter provides clear confirmation of the quantum confinement effect never happens for the case of a non surface passivated SiNW. This is another good advantage of H-passivated SiNW over non-surface passivated SiNW. Finally, it has been observed from these results that the H-passivated SiNWs are best suitable channel materials for designing high performance novel transistors due to their tunable band gap and due to their direct band gap for orientation they are suitable optically active material for photonic applications.
Superlattices and Microstructures, 2018
Graphene nanoribbon (GNR), a new 2D carbon nanomaterial, has some unique features and special pro... more Graphene nanoribbon (GNR), a new 2D carbon nanomaterial, has some unique features and special properties that offer a great potential for interconnect, nanoelectronic devices, optoelectronics, and nanophotonics. This paper reports the structural analysis, electronic properties, and band gaps of a GNR considering different chirality combinations obtained using the p z orbital tight binding model. In structural analysis, the analytical expressions for GNRs have been developed and verified using the simulation for the first time. It has been found that the total number of unit cells and carbon atoms within an overall unit cell and molecular structure of a GNR have been changed with the change in their chirality values which are similar to the values calculated using the developed analytical expressions thus validating both the simulation as well as analytical results. Further, the electronic band structures at different chirality values have been shown for the identification of metallic and semiconductor properties of a GNR. It has been concluded that all zigzag edge GNRs are metallic with very small band gaps range whereas all armchair GNRs show both the metallic and semiconductor nature with very small and high band gaps range. Again, the total number of subbands in each electronic band structure is equal to the total number of carbon atoms present in overall unit cell of the corresponding GNR. The semiconductors GNRs can be used as a channel material in field effect transistor suitable for advanced CMOS technology whereas the metallic GNRs could be used for interconnect.
Superlattices and Microstructures, 2018
Please cite this article as: D. Dass, Structural parameters, electronic properties, and band gaps... more Please cite this article as: D. Dass, Structural parameters, electronic properties, and band gaps of a single walled carbon nanotube: A p z orbital tight binding study,
Applied Surface Science, 2019
Please cite this article as: D. Dass, Effects of surface passivation by hydrogen on the structura... more Please cite this article as: D. Dass, Effects of surface passivation by hydrogen on the structural and electronic properties of a germanium nanowire: A sp3 tight binding study, Applied Surface Science,
Applied Surface Science, 2019
International journal of computational engineering research, Sep 2012
Recently it has been experimentally confirmed that the chirality of a nanotube controls the speed... more Recently it has been experimentally confirmed that the chirality of a nanotube controls the speed of its growth, and the armchair nanotube should grow the fastest. Therefore, chirality is an important parameter in designing a carbon nanotube (CNT) and needs to be investigated for the role it plays in the structure of a CNT. In this paper, we have analytically analyzed the unit cell and molecular structures of various single walled carbon nanotubes (SWCNTs) at different values of chirality combinations. The results suggest that total number of unit cells, carbon atoms and hexagons in each structure of SWCNTs are being changed by changing its chirality. A simple and step by step approach has been followed in describing the analytical expressions of overall unit cell structure, molecular structure, chiral angle and diameter of SWCNTs. The analytical formulations have been verified by simulating different SWCNTs at various chirality values. The simulated results match very well with the mathematical results thus validating, both the simulations as well as analytical expressions.
Journal of Nano-& Electronic Physics, Mar 2013
In this paper, we have studied a double gate nanoscale MOSFET for various channel materials using... more In this paper, we have studied a double gate nanoscale MOSFET for various channel materials using simulation approach. The device metrics considered at the nanometer scale are subthreshold swing (SS), drain induced barrier lowering (DIBL), on and off current, carrier injection velocity (vinj), etc. The channel materials studied are Silicon (Si), Germanium (Ge), Gallium Arsenide (GaAs), Zinc Oxide (ZnO), Zinc Sulfide (ZnS), Indium Arsenide (InAs), Indium Phosphide (InP) and Indium Antimonide (InSb). The results suggest that InSb and InAs materials have highest Ion and lowest Ioff values when used in the channel of the proposed MOSFET. Besides, InSb has the highest values for Ion / Ioff ratio, vinj, transconductance (gm) and improved short channel effects (SS = 59.71 and DIBL = 1.14, both are very close to ideal values). More results such as effect of quantum capacitance verses gate voltage (Vgs), drain current (Ids) vs. gate voltage and drain voltage (Vds), ratio of transconductance (gm) and drain current (Id) vs. gate voltage, average velocity vs. gate voltage and injection velocity (Vinj) for the mentioned channel materials have been investigated. Various results obtained indicate that InSb and InAs as channel material appear to be suitable for high performance logic and even low operating power requirements for future nanoscale devices as suggested by latest ITRS reports.
International Journal on Organic Electronics, Jan 2013
The exponential rise in the density of silicon CMOS transistors has now reached a limit and threa... more The exponential rise in the density of silicon CMOS transistors has now reached a limit and threatening to end the microelectronics revolution. To tackle this difficulty, group III-V compound semiconductors due to their outstanding electron transport properties and high mobility are very actively being researched as channel materials for future highly scaled CMOS devices. In this paper, we have studied a ballistic nanoscale MOSFET using simulation approach by replacing silicon in the channel by III-V compounds. The channel materials considered are silicon (Si), Gallium arsenide (GaAs), Indium arsenide (InAs), Indium Phosphide (InP) and Indium Antimonide (InSb). The device metrics considered at the nanometer scale are subthreshold swing, Drain induced barrier lowering, on and off current, carrier injection velocity and switching speed. These channel materials have been studied using various dielectric constants. It has been observed that Indium Antimonide (InSb) has higher on current, higher transconductance, idealistic subthreshold swing, higher output conductance, higher carrier injection velocity and comparable voltage gain compared to Silicon, thus, making InSb as a possible candidate to be used as channel material in future nanoscale devices.
The African Review of Physics, Feb 1, 2013
Carbon nanotubes are nanomaterials, which can be used in various areas due to their superior elec... more Carbon nanotubes are nanomaterials, which can be used in various areas due to their superior electrical and mechanical properties and has become the most promising candidate for nanoelectronics, nonodevices and nanocomposites. Chirality is an important parameter in designing a carbon nanotube (CNT) and needs to be investigated for the role it plays in the structure of a CNT. Recently it has been experimentally confirmed that the chirality of a nanotube controls the speed of its growth, and the armchair nanotube should grow the fastest. In this paper, we have presented various electrical parameters for an armchair CNT such as potential, electric field, electron current, charge density, I-V characteristics, and resistance variations by adjusting the input parameters such as chirality, length of the CNT, ambient temperature, and applied voltage. It has been observed that with the increase in chirality or chiral values of CNT, the electron current enhances whereas the resistance decrease. The charge density and I-V characteristics can be changed by varying chirality but it does not affect potential and electric field. The paper also highlights the effect of various parameters such as length of armchair CNT, ambient temperature and applied voltage on the performance of armchair CNT.
Journal of Nano-& Electronic Physics, May 4, 2013
As scaling down Si MOSFET devices degrade device performance in terms of short channel effects. C... more As scaling down Si MOSFET devices degrade device performance in terms of short channel effects. Carbon nanotube field effect transistor (CNTFET) is one of the novel nanoelectronics devices that overcome those MOSFET limitations. The carbon nanotube field effect transistors (CNTFETs) have been explored and proposed to be the promising candidate for the next generation of integrated circuit (IC) devices. To explore the role of CNTFETs in future integrated circuits, it is important to evaluate their performance. However, to do that we need a model that can accurately describe the behavior of the CNTFETs so that the design and evaluation of circuits using these devices can be made. In this paper, we have investigated the effect of scaling gate insulator thickness on the device performance of cylindrical shaped ballistic CNTFET in terms of transfer characteristics, output characteristics, average velocity, gm/Id ratio, mobile charge, quantum capacitance/insulator capacitance, drive current (Ion), Ion / Ioff ratio, transconductance, and output conductance. We concluded that the device metrics such as Ion, Ion / Ioff ratio, transconductance, and output conductance increases with the decrease in gate insulator thickness. Also, we concluded that the gate insulator thickness reduction causes subthreshold slope close to the theoretical limit of 60 mV/decade and DIBL close to zero at room temperature.