Dan Nicolaescu - Academia.edu (original) (raw)
Papers by Dan Nicolaescu
Journal of Vacuum Science & Technology B, 2006
A two-dimensional model of quasi-free-electrons is used to compute the electron axial distributio... more A two-dimensional model of quasi-free-electrons is used to compute the electron axial distribution on a carbon nanotube and the energy distribution of the field emitted electrons. The nature of the substrate-nanotube contact is taken into account by varying the boundary condition for the electronic wave function. In qualitative agreement with the experimental results to date, regular patterns of the axial
Ultramicroscopy, 2001
A theoretical framework for the electron field emission from carbon nanotubes (CNTs) is discussed... more A theoretical framework for the electron field emission from carbon nanotubes (CNTs) is discussed. Using the tunneling theory, the influence of the detailed electron energy dispersion is proven to be of little importance for the electron field emission. By means of numerical computations in a simplified model, the influence of the environment on the local field on a CNT is discussed for an aligned CNT film. In a simple triangular model for the potential energy barrier at the tube end, a tunneling probability was obtained. A statistical model was developed for the structural and functional parameters of aligned CNT films. Practical CNT films of excellent alignment, obtained directly on a tungsten wire by plasma-enhanced chemical vapor deposition, were analyzed by this statistical model. Their distribution in the enhancement factors was thus deduced. An indirect method to get the average electrical parameters of the film using only a limited amount of experimental data was thus established. r (D. Nicolaescu). 0304-3991/01/$ -see front matter r 2001 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 -3 9 9 1 ( 0 1 ) 0 0 1 0 7 -3
Applied Surface Science, 1999
Ž . Chemical vapour-deposited CVD amorphous silicon carbide a-SiC and diamond-like carbon DLC thi... more Ž . Chemical vapour-deposited CVD amorphous silicon carbide a-SiC and diamond-like carbon DLC thin films were Ž . realised on p-type silicon field emitter arrays FEAs in order to investigate their field emission properties. The FEA Ž . geometry was investigated by scanning electron microscopy SEM , the film morphology by scanning force microscopy Ž . Ž . SFM and by SEM, and the film structure by X-ray photoelectron spectroscopy XPS . Field emission properties of FEAs were determined in high vacuum conditions. a-SiCrp-Si in comparison with DLCrp-Si emitter arrays have higher current emission at lower external fields. The upper limits of the field emission current densities were 2.4 mArcm 2 for an electric field of 25 Vrmm in the case of SiC and 0.8 mArcm 2 for the electric field of 42 Vrmm in the case of DLC films. q 1999 Elsevier Science B.V. All rights reserved. PACS: 85.45.B; 81.15.G; 68.55.J; 61.16.C Ž . Ž .
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1995
... 6 h 10 * 1 1 * 50 200 500;1000 h 10 * 1 1 * 50 100;200 500 7 gm h 10 * 1 1 * 50 2... more ... 6 h 10 * 1 1 * 50 200 500;1000 h 10 * 1 1 * 50 100;200 500 7 gm h 10 * 1 1 * 50 200 500;1000 534 Dan Nicolaescu: Electric field-potential correlation factors 534 J. Vac. Sci. Technol. B, Vol. ... Microeng. 2, 43 1992. 5S. Iannazzo, Solid-State Electron. 36, 301 1993. 6W. ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000
ABSTRACT In this study we analyze a new vacuum microelectronics (VM) magnetic field sensor based ... more ABSTRACT In this study we analyze a new vacuum microelectronics (VM) magnetic field sensor based on a simple configuration with a single-gated wedge emitter with a split anode current as detection system. The actuation of such a device has been simulated using different numerical approaches including a full determination of electrostatic potentials with an accurate description of the fields at the wedge-like emitter, the propagation of electrons inside the device, and the evaluation of the current density distributions at the anode detector screen. This device presents sensor sensitivities higher than those of conventional magnetic field sensors, and similar to other VM double-gated sensors. The dependence of the sensitivity on the geometric parameters and control voltages is discussed. © 2000 American Vacuum Society.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
Applied Surface Science, 1999
In the present work, we analyze the operation of a pressure sensor based on an array of wedge emi... more In the present work, we analyze the operation of a pressure sensor based on an array of wedge emitters. The device comprises a silicon membrane acting as the anode of the device put in front of the emitter array. When the external pressure bends the membrane, there is a change in the separation tip membrane giving rise to a modification of the field emission current. An analytical solution has been used to calculate the deflection of the silicon diaphragm under different pressure conditions and a computer code was developed to compute the emission current from the array. The device shows high sensitivity allowing the determination of very small changes to the pressure at constant voltage working mode. Alternatively, broad ranges of pressure changes can be measured using a constant current mode. q
Japanese Journal of Applied Physics, 2005
Field emission arrays (FEAs) consisting of hafnium carbide (HfC)-coated silicon (Si) emitters (Hf... more Field emission arrays (FEAs) consisting of hafnium carbide (HfC)-coated silicon (Si) emitters (HfC emitters) have been fabricated. The FEA emission properties were measured in ultrahigh-vacuum conditions and after being subjected to Ar and O2 residual gases with partial pressures in the range of 10-6 to 10-4 Pa. The influence of residual gases on the FEA field emission properties has been
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
The traditional approach of analyzing field emission ͑FE͒ data using the ''emission area'' and ''... more The traditional approach of analyzing field emission ͑FE͒ data using the ''emission area'' and ''field enhancement'' factors is faulty. Instead, the emission current I should be computed through integration of the tunneling current density over the emitter surface, taking into account the local variation of the electric field. As a consequence, FE data represented as Fowler-Nordheim ͑FN͒ plots ln(I/V 2 ) versus 1/V are nonlinear regardless of the model used to derive the electric field and the modified FN plot ln(I/V 3 ) versus 1/V is more suitable for representing the FE data in a linear way. In this article, a general approach for extraction of model parameters using wide-range FE data is proposed. A nonlinear least-square fitting procedure is applied to emission data based on the statistical gated emitter/triode model tailored for the particular emitter configuration. Uniform distributions for the emitter radius R and work function in the array are considered, although other distributions may be included in the model. Deriving an accurate analytical formula for computing the electric field on the emitter tip is a crucial step for obtaining good modeling results. At least two model parameters from the set comprising R, and their dispersion range ⌬R, ⌬ can thus be derived. Comparison with experimental results is provided.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
The influence of different forms of electron energy dispersion relations on the field emission pr... more The influence of different forms of electron energy dispersion relations on the field emission properties of carbon nanotubes is investigated
Applied Surface Science, 1996
A model is developed in order to analyse a magnetic sensor based on vacuum field emission. The op... more A model is developed in order to analyse a magnetic sensor based on vacuum field emission. The operation of the sensor is based on the deflection of the electron current obtained through cold emission due to the Lorentz force. The electrons' velocities obtained in vacuum are higher than in a semiconductor, being not limited by scattering processes. They allow for higher electron deviations and sensor sensitivities to be obtained. The sensor based on cold emission is less sensitive to environmental conditions (temperature and radiation) compared with semiconductor based sensors. The field emission diode model considered comprises two co-axial metallic cylinders placed in vacuum. The spacing between cylinders is d and the diode difference of potential is V a. The inner cylinder acts as emitter. The outer cylinder acts as split-anode with two active parts of equal angular aperture. The differential signal from the two anodes is a function of the applied magnetic field B, which is parallel to the cylinders' axis. The trajectory of the emitted electrons is obtained both in analytical and numerical form. The sensor relative sensitivity S and magnetic field measuring range B m are defined and computed. It is shown that B m increases linearly with V a and 1/d, whilst S varies in the opposite way, decreasing with V a and linearly increasing with d. High sensor relative sensitivities are obtained, in the range several hundred to thousand %/T. These values compare well with experimental data. * Corresponding author. Fax: +40 1 3127519. 1 Fax:+40 1 3123127. netic sensor could be designed based on this operating principle. Recently, the first such vacuum magnetic sensor has been reported [1]. This sensor is a lateral emitting microtriode (based on a linear comb-shaped emitter array) with the anode split into two parts. The current imbalance between the splitanodes is a measure of the applied magnetic field.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000
... 2000)]. MJ Gilkes, D. Nicolaescu, PR Wilshaw. Abstract. Measurements ... with time. ACKNOWLED... more ... 2000)]. MJ Gilkes, D. Nicolaescu, PR Wilshaw. Abstract. Measurements ... with time. ACKNOWLEDGMENTS. The authors would like to thank Professor P. Dobson, Dr. M. Huang, and Dr. E. Holland for their contributions to this work. References. ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005
Ring-shaped images may appear under high field emission conditions for very thin carbon nanotubes... more Ring-shaped images may appear under high field emission conditions for very thin carbon nanotubes (CNTs). Such image patterns cannot be explained by the corresponding field enhancement only. A model for electron field emission from the CNT is developed. The model refers to a capped nanotube (with cylindrical body and hemispherical cap). It is assumed that for high emission currents/high local temperatures, part of the electrons behave as quasi-free. As a result, the spatial confinement quantization of their states appears. The Schrodinger equation for the single electron can be solved separately on the cylindrical and spherical parts of the structure and the corresponding solutions can be connected smoothly at the circular intersection of the two regions. Many electronic states that are possible on the two regions separately turn out to be forbidden for the capped nanotube. The selection of the possible electronic states under the aforementioned complex conditions is determined by the geometric parameters of the tube, namely the ratio between its length and diameter. The occupation of the allowed one- electron states is considered as governed by the usual Fermi statistics. Together with the quantum probability of finding an electron in some specified area of the surface, this gives the electron distribution on the tube, which is one of the key factors determining the electron field emission from the CNT. Another key factor is the applied extraction field. The extraction field has been numerically computed using Simion nanotube-on-post diode configuration.
Japanese Journal of Applied Physics, 2004
Films of vertically aligned carbon nanotubes (CNTs) have recently being grown within patterned ar... more Films of vertically aligned carbon nanotubes (CNTs) have recently being grown within patterned areas. Nanotriodes based on such CNT arrays as field emitters have the potential of improved performance if devising a way to subject the nanotubes to uniform extraction fields. In this paper, we propose and model an optimized field emission nanotriode with aligned CNTs of variable heights. The
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005
ABSTRACT
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1999
ABSTRACT Several results have been reported so far as concerns magnetic sensors based on field em... more ABSTRACT Several results have been reported so far as concerns magnetic sensors based on field emission arrays. In this paper, a new concept magnetic sensor is proposed and its operation is analysed using a numerical model. The sensor comprises an array of integrated electron emitters each one formed by a tip at voltage Vt, and two deflection electrodes at potentials +V/2 and -V/2. The deflection of the beam due to the Lorentz force can be compensated by a suitable choice of the electric field formed between the electrodes. In this way, a correlation V(B) between the voltage V applied between two electrodes and the magnetic field B to be measured is obtained
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
The operation of nanotriodes using carbon nanotubes (CNTs) as field emitters is modeled. The devi... more The operation of nanotriodes using carbon nanotubes (CNTs) as field emitters is modeled. The device characteristics are computed as function of device geometry and functional parameters. Several device design suggestions are drawn
Applied Surface Science, 1996
Electron field emission is obtained using high enough ( > 1 V/nm) electric fields. Such local fie... more Electron field emission is obtained using high enough ( > 1 V/nm) electric fields. Such local fields are usually obtained using sharp emitters. An alternative approach is to cover the otherwise blunt emitter (BE) with a porous silicon (PS) layer. The PS is composed of many fibrils with dimensions of several nm which act as "nano-emitters". In this article such an emitter is considered as part of a vertical field emission microtriode (FEMT). The BE has spherical tip and conical body and protrudes through the gate circular opening, allowing the FEMT operation in the collector-assisted mode. An electric field multiplication approximation is studied using both an analytical and a numerical emitter model. The field multiplication means that the fibril increases the local electric field, which is already increased by the BE as compared with the uniform field at large distances from it. This approximation is valid as long as the fibril dimensions are much smaller than the BE ones. The fibrils mutual influence on the field is studied separately and taken into account for the FEMT case. The emission current is computed through integration of the Fowler-Nordheim J(E) current density-electric field relationship over the BE and fibrils area. Comparison is provided with the case of BE not covered with PS. The emission current is obtained as function of model parameters. FEMT modelling results include transconductance, capacitance, cut-off frequency and static gain. Reference to experimental results is provided. 0169-4332/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved SSDI 01 69-4332(95)00354-1
Applied Surface Science, 1997
A fabrication technology for porous silicon (PS) field emitters for display applications is descr... more A fabrication technology for porous silicon (PS) field emitters for display applications is described. Silicon blunt emitters prepared on p-type silicon wafers of 30 Ω cm resistivity were covered with a thin layer of porous silicon using an electrochemical anodization in ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2001
Journal of Vacuum Science & Technology B, 2006
A two-dimensional model of quasi-free-electrons is used to compute the electron axial distributio... more A two-dimensional model of quasi-free-electrons is used to compute the electron axial distribution on a carbon nanotube and the energy distribution of the field emitted electrons. The nature of the substrate-nanotube contact is taken into account by varying the boundary condition for the electronic wave function. In qualitative agreement with the experimental results to date, regular patterns of the axial
Ultramicroscopy, 2001
A theoretical framework for the electron field emission from carbon nanotubes (CNTs) is discussed... more A theoretical framework for the electron field emission from carbon nanotubes (CNTs) is discussed. Using the tunneling theory, the influence of the detailed electron energy dispersion is proven to be of little importance for the electron field emission. By means of numerical computations in a simplified model, the influence of the environment on the local field on a CNT is discussed for an aligned CNT film. In a simple triangular model for the potential energy barrier at the tube end, a tunneling probability was obtained. A statistical model was developed for the structural and functional parameters of aligned CNT films. Practical CNT films of excellent alignment, obtained directly on a tungsten wire by plasma-enhanced chemical vapor deposition, were analyzed by this statistical model. Their distribution in the enhancement factors was thus deduced. An indirect method to get the average electrical parameters of the film using only a limited amount of experimental data was thus established. r (D. Nicolaescu). 0304-3991/01/$ -see front matter r 2001 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 -3 9 9 1 ( 0 1 ) 0 0 1 0 7 -3
Applied Surface Science, 1999
Ž . Chemical vapour-deposited CVD amorphous silicon carbide a-SiC and diamond-like carbon DLC thi... more Ž . Chemical vapour-deposited CVD amorphous silicon carbide a-SiC and diamond-like carbon DLC thin films were Ž . realised on p-type silicon field emitter arrays FEAs in order to investigate their field emission properties. The FEA Ž . geometry was investigated by scanning electron microscopy SEM , the film morphology by scanning force microscopy Ž . Ž . SFM and by SEM, and the film structure by X-ray photoelectron spectroscopy XPS . Field emission properties of FEAs were determined in high vacuum conditions. a-SiCrp-Si in comparison with DLCrp-Si emitter arrays have higher current emission at lower external fields. The upper limits of the field emission current densities were 2.4 mArcm 2 for an electric field of 25 Vrmm in the case of SiC and 0.8 mArcm 2 for the electric field of 42 Vrmm in the case of DLC films. q 1999 Elsevier Science B.V. All rights reserved. PACS: 85.45.B; 81.15.G; 68.55.J; 61.16.C Ž . Ž .
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1995
... 6 h 10 * 1 1 * 50 200 500;1000 h 10 * 1 1 * 50 100;200 500 7 gm h 10 * 1 1 * 50 2... more ... 6 h 10 * 1 1 * 50 200 500;1000 h 10 * 1 1 * 50 100;200 500 7 gm h 10 * 1 1 * 50 200 500;1000 534 Dan Nicolaescu: Electric field-potential correlation factors 534 J. Vac. Sci. Technol. B, Vol. ... Microeng. 2, 43 1992. 5S. Iannazzo, Solid-State Electron. 36, 301 1993. 6W. ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000
ABSTRACT In this study we analyze a new vacuum microelectronics (VM) magnetic field sensor based ... more ABSTRACT In this study we analyze a new vacuum microelectronics (VM) magnetic field sensor based on a simple configuration with a single-gated wedge emitter with a split anode current as detection system. The actuation of such a device has been simulated using different numerical approaches including a full determination of electrostatic potentials with an accurate description of the fields at the wedge-like emitter, the propagation of electrons inside the device, and the evaluation of the current density distributions at the anode detector screen. This device presents sensor sensitivities higher than those of conventional magnetic field sensors, and similar to other VM double-gated sensors. The dependence of the sensitivity on the geometric parameters and control voltages is discussed. © 2000 American Vacuum Society.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
Applied Surface Science, 1999
In the present work, we analyze the operation of a pressure sensor based on an array of wedge emi... more In the present work, we analyze the operation of a pressure sensor based on an array of wedge emitters. The device comprises a silicon membrane acting as the anode of the device put in front of the emitter array. When the external pressure bends the membrane, there is a change in the separation tip membrane giving rise to a modification of the field emission current. An analytical solution has been used to calculate the deflection of the silicon diaphragm under different pressure conditions and a computer code was developed to compute the emission current from the array. The device shows high sensitivity allowing the determination of very small changes to the pressure at constant voltage working mode. Alternatively, broad ranges of pressure changes can be measured using a constant current mode. q
Japanese Journal of Applied Physics, 2005
Field emission arrays (FEAs) consisting of hafnium carbide (HfC)-coated silicon (Si) emitters (Hf... more Field emission arrays (FEAs) consisting of hafnium carbide (HfC)-coated silicon (Si) emitters (HfC emitters) have been fabricated. The FEA emission properties were measured in ultrahigh-vacuum conditions and after being subjected to Ar and O2 residual gases with partial pressures in the range of 10-6 to 10-4 Pa. The influence of residual gases on the FEA field emission properties has been
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
The traditional approach of analyzing field emission ͑FE͒ data using the ''emission area'' and ''... more The traditional approach of analyzing field emission ͑FE͒ data using the ''emission area'' and ''field enhancement'' factors is faulty. Instead, the emission current I should be computed through integration of the tunneling current density over the emitter surface, taking into account the local variation of the electric field. As a consequence, FE data represented as Fowler-Nordheim ͑FN͒ plots ln(I/V 2 ) versus 1/V are nonlinear regardless of the model used to derive the electric field and the modified FN plot ln(I/V 3 ) versus 1/V is more suitable for representing the FE data in a linear way. In this article, a general approach for extraction of model parameters using wide-range FE data is proposed. A nonlinear least-square fitting procedure is applied to emission data based on the statistical gated emitter/triode model tailored for the particular emitter configuration. Uniform distributions for the emitter radius R and work function in the array are considered, although other distributions may be included in the model. Deriving an accurate analytical formula for computing the electric field on the emitter tip is a crucial step for obtaining good modeling results. At least two model parameters from the set comprising R, and their dispersion range ⌬R, ⌬ can thus be derived. Comparison with experimental results is provided.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
The influence of different forms of electron energy dispersion relations on the field emission pr... more The influence of different forms of electron energy dispersion relations on the field emission properties of carbon nanotubes is investigated
Applied Surface Science, 1996
A model is developed in order to analyse a magnetic sensor based on vacuum field emission. The op... more A model is developed in order to analyse a magnetic sensor based on vacuum field emission. The operation of the sensor is based on the deflection of the electron current obtained through cold emission due to the Lorentz force. The electrons' velocities obtained in vacuum are higher than in a semiconductor, being not limited by scattering processes. They allow for higher electron deviations and sensor sensitivities to be obtained. The sensor based on cold emission is less sensitive to environmental conditions (temperature and radiation) compared with semiconductor based sensors. The field emission diode model considered comprises two co-axial metallic cylinders placed in vacuum. The spacing between cylinders is d and the diode difference of potential is V a. The inner cylinder acts as emitter. The outer cylinder acts as split-anode with two active parts of equal angular aperture. The differential signal from the two anodes is a function of the applied magnetic field B, which is parallel to the cylinders' axis. The trajectory of the emitted electrons is obtained both in analytical and numerical form. The sensor relative sensitivity S and magnetic field measuring range B m are defined and computed. It is shown that B m increases linearly with V a and 1/d, whilst S varies in the opposite way, decreasing with V a and linearly increasing with d. High sensor relative sensitivities are obtained, in the range several hundred to thousand %/T. These values compare well with experimental data. * Corresponding author. Fax: +40 1 3127519. 1 Fax:+40 1 3123127. netic sensor could be designed based on this operating principle. Recently, the first such vacuum magnetic sensor has been reported [1]. This sensor is a lateral emitting microtriode (based on a linear comb-shaped emitter array) with the anode split into two parts. The current imbalance between the splitanodes is a measure of the applied magnetic field.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000
... 2000)]. MJ Gilkes, D. Nicolaescu, PR Wilshaw. Abstract. Measurements ... with time. ACKNOWLED... more ... 2000)]. MJ Gilkes, D. Nicolaescu, PR Wilshaw. Abstract. Measurements ... with time. ACKNOWLEDGMENTS. The authors would like to thank Professor P. Dobson, Dr. M. Huang, and Dr. E. Holland for their contributions to this work. References. ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005
Ring-shaped images may appear under high field emission conditions for very thin carbon nanotubes... more Ring-shaped images may appear under high field emission conditions for very thin carbon nanotubes (CNTs). Such image patterns cannot be explained by the corresponding field enhancement only. A model for electron field emission from the CNT is developed. The model refers to a capped nanotube (with cylindrical body and hemispherical cap). It is assumed that for high emission currents/high local temperatures, part of the electrons behave as quasi-free. As a result, the spatial confinement quantization of their states appears. The Schrodinger equation for the single electron can be solved separately on the cylindrical and spherical parts of the structure and the corresponding solutions can be connected smoothly at the circular intersection of the two regions. Many electronic states that are possible on the two regions separately turn out to be forbidden for the capped nanotube. The selection of the possible electronic states under the aforementioned complex conditions is determined by the geometric parameters of the tube, namely the ratio between its length and diameter. The occupation of the allowed one- electron states is considered as governed by the usual Fermi statistics. Together with the quantum probability of finding an electron in some specified area of the surface, this gives the electron distribution on the tube, which is one of the key factors determining the electron field emission from the CNT. Another key factor is the applied extraction field. The extraction field has been numerically computed using Simion nanotube-on-post diode configuration.
Japanese Journal of Applied Physics, 2004
Films of vertically aligned carbon nanotubes (CNTs) have recently being grown within patterned ar... more Films of vertically aligned carbon nanotubes (CNTs) have recently being grown within patterned areas. Nanotriodes based on such CNT arrays as field emitters have the potential of improved performance if devising a way to subject the nanotubes to uniform extraction fields. In this paper, we propose and model an optimized field emission nanotriode with aligned CNTs of variable heights. The
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005
ABSTRACT
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1999
ABSTRACT Several results have been reported so far as concerns magnetic sensors based on field em... more ABSTRACT Several results have been reported so far as concerns magnetic sensors based on field emission arrays. In this paper, a new concept magnetic sensor is proposed and its operation is analysed using a numerical model. The sensor comprises an array of integrated electron emitters each one formed by a tip at voltage Vt, and two deflection electrodes at potentials +V/2 and -V/2. The deflection of the beam due to the Lorentz force can be compensated by a suitable choice of the electric field formed between the electrodes. In this way, a correlation V(B) between the voltage V applied between two electrodes and the magnetic field B to be measured is obtained
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
The operation of nanotriodes using carbon nanotubes (CNTs) as field emitters is modeled. The devi... more The operation of nanotriodes using carbon nanotubes (CNTs) as field emitters is modeled. The device characteristics are computed as function of device geometry and functional parameters. Several device design suggestions are drawn
Applied Surface Science, 1996
Electron field emission is obtained using high enough ( > 1 V/nm) electric fields. Such local fie... more Electron field emission is obtained using high enough ( > 1 V/nm) electric fields. Such local fields are usually obtained using sharp emitters. An alternative approach is to cover the otherwise blunt emitter (BE) with a porous silicon (PS) layer. The PS is composed of many fibrils with dimensions of several nm which act as "nano-emitters". In this article such an emitter is considered as part of a vertical field emission microtriode (FEMT). The BE has spherical tip and conical body and protrudes through the gate circular opening, allowing the FEMT operation in the collector-assisted mode. An electric field multiplication approximation is studied using both an analytical and a numerical emitter model. The field multiplication means that the fibril increases the local electric field, which is already increased by the BE as compared with the uniform field at large distances from it. This approximation is valid as long as the fibril dimensions are much smaller than the BE ones. The fibrils mutual influence on the field is studied separately and taken into account for the FEMT case. The emission current is computed through integration of the Fowler-Nordheim J(E) current density-electric field relationship over the BE and fibrils area. Comparison is provided with the case of BE not covered with PS. The emission current is obtained as function of model parameters. FEMT modelling results include transconductance, capacitance, cut-off frequency and static gain. Reference to experimental results is provided. 0169-4332/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved SSDI 01 69-4332(95)00354-1
Applied Surface Science, 1997
A fabrication technology for porous silicon (PS) field emitters for display applications is descr... more A fabrication technology for porous silicon (PS) field emitters for display applications is described. Silicon blunt emitters prepared on p-type silicon wafers of 30 Ω cm resistivity were covered with a thin layer of porous silicon using an electrochemical anodization in ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2001