Cyber security affects literally every computer user. A multibillion world-wide industry is tryin... more Cyber security affects literally every computer user. A multibillion world-wide industry is trying to solve this growing and very dangerous problem. And all these efforts are focused on fighting malicious software. However, the malicious hardware is even more of a threat and much harder to detect. Our company - Electronics of the Future, Inc. - has developed technology and a family of products to detect the malicious hardware. Electronics of the Future is using terahertz scanning technology and Artificial Intelligence to detect genuine and faked integrated circuits.
Numerous applications of terahertz communication and sensing technology require powerful electron... more Numerous applications of terahertz communication and sensing technology require powerful electronic sources and sensitive detectors. Recently proposed “plasmonic boom” terahertz devices require the electron velocity repeatedly cross the plasma velocity in periodic electronic structures. Such devices could increase the generated power and detection sensitivity by orders of magnitude. However, they require tuning boundary conditions at heterodimensional interfaces and decreasing the velocity of the plasmons. We propose using the protruding side regions attached to a plasmonic channel – “plasmonic stubs” – to control the boundary conditions and slow down plasmons in a controllable and tunable fashion. Using the transmission line modeling approach, we derive the expression for the input impedance of the device with a stub and show the input impedance could be tuned from minus to plus infinity. We derive and solve the dispersion equation for the plasmons and show the tunable plasma velocity decrease. These results are important for design, characterization, modeling, and parameter extraction of the next generation of THz electronic devices and circuits.
International Journal of High Speed Electronics and Systems, 1998
We present a review of modern analog simulation techniques based on time- and frequency-domain al... more We present a review of modern analog simulation techniques based on time- and frequency-domain algorithms. For time-domain techniques, important topics such as circuit decomposition, relaxation methods, latency, multirate integration, continuation methods, parallel algorithms, and finite difference time-domain methods are discussed. Frequency-domain simulation techniques included are harmonic balance, harmonic relaxation, harmonic-Newton, spectral balance, methods for quasiperiodic circuits, and device modeling for frequency domain simulators. Also included are examples of modern simulators.
Renewable Energy and the Environment Optics and Photonics Congress, 2012
ABSTRACT Cultural differences in selecting the color quality of illumination were investigated us... more ABSTRACT Cultural differences in selecting the color quality of illumination were investigated using a solid-state source of light with tunable color-rendition properties. The differences were found to depend on the familiarity of illuminated objects.
Unique properties of GaN/AlN/InN heterostructures make them superior for high power applications.... more Unique properties of GaN/AlN/InN heterostructures make them superior for high power applications. The key issues in the device designs are achieving normally-off operation, controlling the electric field distribution in the device channel to prevent breakdown, eliminating or reducing non-ideal effects causing reliability issues, and providing for efficient heat dissipation. High electric fields at the gate edges lead to an additional strain and hot electron effects causing the current collapse and gate lag. Quantum well designs (e.g. incorporating an InGaN or GaN quantum well between the wide band gap AlGaN barrier layer and GaN or AlGaN buffer) might control the wave function penetration and the real space transfer and increase the breakdown voltage. Insulated gate heterostructure HFETs (MOSHFETs) demonstrated superior performance and reliability. Field plates, recessed and double recessed gates, drain field controlled electrodes have been used to control current collapse and impro...
ABSTRACT Mixing of two optical beams with close frequencies in photoconductive structures or thei... more ABSTRACT Mixing of two optical beams with close frequencies in photoconductive structures or their response to ultrashort optical pulses are widely used for the generation of terahertz (THz) electromagnetic radiation. The THz radiation produced by optically excited plasma oscillations in p-i-n structures has been observed by some teams. In this communication, we consider a heterostructure akin to a field-effect transistor with high electron mobility in its two-dimensional channel and report on the modeling of THz oscillations caused by optical signals in this heterostructure. The features of such a heterostructure are associated with the existence of weakly damped electron plasma oscillations and possibility of their resonant excitation, so that the two-dimensional electron channel serves as a resonant cavity with rather high quality factor. A conception of THz photomixing using the excitation of standing plasma waves (plasma oscillations) in the heterostructure under consideration has recently been proposed by the authors. We demostrate that due to the excitation of the electron plasma oscillations in the channel by the photogenerated electrons and holes, the heterostructure in question exhibits a pronounced resonant response leading to high amplitudes of the ac photocurrent oscillations. As shown, this can result in substantially higher efficiency of the THz radiation generation by optical signals than that in p-i-n structures.
We show that the steady state with a dc current in ungated 2D electron gas might exhibit an insta... more We show that the steady state with a dc current in ungated 2D electron gas might exhibit an instability related to asymmetrical boundary conditions, which is similar to the "shallow water" instability in the gated 2D electron gas. The mathematics of the problem corresponds to "deep water" solutions for plasma waves. In the ideal case, the boundary conditions should correspond to zero ac voltage at the source and zero ac current at the drain, similar to the conditions for instability in a field effect transistor. Such boundary conditions can be realized using several different device configurations. For similar device dimensions, the plasma wave generated in an ungated 2D device will have much higher frequency compared to that in gated devices.
... Electron Devices, ED-26, No. 11, pp. 1677-1683, 1979. 2. Lester Eastman, Richard Stall, David... more ... Electron Devices, ED-26, No. 11, pp. 1677-1683, 1979. 2. Lester Eastman, Richard Stall, David Woodard, Niru Dandekar, Colin Wood, Michael Shur and m* = 0.067 r! ' u = 3m /vs/ e / 2 1 / / / / / J = 0.05 x 10 3 A/ cm 2 I 5 6 7 3910 15 20 B (IcGs) Fig. ...
Transferred electron devices can be used as oscillators owing to the negative differential resist... more Transferred electron devices can be used as oscillators owing to the negative differential resistance related to the intervalley transfer of electrons.
The electron density of the two-dimensional electron gas in modulation doped structures is calcul... more The electron density of the two-dimensional electron gas in modulation doped structures is calculated as a function of the doping density in (Al,Ga)As, the thickness of the undoped (Al,Ga)As layer, the lattice temperature, and other device parameters. The results of the calculation show that the depletion approximation is not accurate enough and that the Fermi–Dirac statistics (rather than the Boltzmann statistics) should be used in the calculation. A simple analytical model which takes these factors into account is shown to be in good agreement with our computer calculations and experimental data. The obtained results may be used to evaluate the maximum intrinsic transconductance and the maximum gate voltage swing for the modulation doped field effect transistors.
We demonstrate that the performance of hot-electron transistors and other ballistic devices can b... more We demonstrate that the performance of hot-electron transistors and other ballistic devices can be greatly improved if a focused beam of energetic electrons is injected into the active region of a high-speed device. The results of the Monte Carlo simulations of 72 000 electrons show that the angular distribution of electrons arriving at the collector of a hot-electron transistor is sharper since those electrons injected into the base under large angles primarily contribute to the base current. Our calculations also confirm that ballistic motion may be considerably enhanced by the built-in electric field in the base region. Based on these results, we propose a new device—the double base hot-electron transistor—where the first base acts as an ‘‘electron gun’’ focusing and accelerating the electron beam, which is then injected into the second (active) base where an input signal is applied. Our calculations show that the mean transit time of electrons traversing the active base can be c...
We report on low frequency noise and field-effect mobility in strained-Si surface n-channel metal... more We report on low frequency noise and field-effect mobility in strained-Si surface n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) grown on relaxed virtual substrates with a Ge concentration varying between 0% and 30%. An increased Ge concentration results in higher intrinsic field-effect mobility, increasing from 380cm2V−1s−1 for the unstrained channel to 865cm2V−1s−1 for the strained-Si MOSFET on 30% relaxed SiGe virtual substrate. However, the higher mobility is traded off for increased substrate leakage currents and increased 1∕f (flicker) noise. It is suggested that flicker noise is due to traps in the oxide layer. The density of traps increases from 2×1017eV−1cm−3 for 0% Ge to 2.3×1018eV−1cm−3 for the 30% Ge virtual substrate.
In this paper, compact analytical model for the heterostructure field-effect transistor (HFET) cu... more In this paper, compact analytical model for the heterostructure field-effect transistor (HFET) current-voltage (I-V) characteristics, accounting for the large-signal dispersion, also referred to as current collapse, is presented. The model is based upon an experimentally established fact that the dispersion is mainly due to carrier trapping at the source and drain sides of the gate edges. In wide-bandgap heterostructures like AlGaN/GaN, the characteristic trapping-generation times are several orders of magnitude longer than the signal period at typical operating frequencies. Thus, the radio frequency signal "sees" an averaged I-V characteristic resulting from carrier trapping-generation. The approach, based on this difference, leads to a compact quasi-steady-state analytical model of the HFET I -V characteristics that can be easily implemented in device-circuit simulators. The model shows close agreement with the experimental data
Cyber security affects literally every computer user. A multibillion world-wide industry is tryin... more Cyber security affects literally every computer user. A multibillion world-wide industry is trying to solve this growing and very dangerous problem. And all these efforts are focused on fighting malicious software. However, the malicious hardware is even more of a threat and much harder to detect. Our company - Electronics of the Future, Inc. - has developed technology and a family of products to detect the malicious hardware. Electronics of the Future is using terahertz scanning technology and Artificial Intelligence to detect genuine and faked integrated circuits.
Numerous applications of terahertz communication and sensing technology require powerful electron... more Numerous applications of terahertz communication and sensing technology require powerful electronic sources and sensitive detectors. Recently proposed “plasmonic boom” terahertz devices require the electron velocity repeatedly cross the plasma velocity in periodic electronic structures. Such devices could increase the generated power and detection sensitivity by orders of magnitude. However, they require tuning boundary conditions at heterodimensional interfaces and decreasing the velocity of the plasmons. We propose using the protruding side regions attached to a plasmonic channel – “plasmonic stubs” – to control the boundary conditions and slow down plasmons in a controllable and tunable fashion. Using the transmission line modeling approach, we derive the expression for the input impedance of the device with a stub and show the input impedance could be tuned from minus to plus infinity. We derive and solve the dispersion equation for the plasmons and show the tunable plasma velocity decrease. These results are important for design, characterization, modeling, and parameter extraction of the next generation of THz electronic devices and circuits.
International Journal of High Speed Electronics and Systems, 1998
We present a review of modern analog simulation techniques based on time- and frequency-domain al... more We present a review of modern analog simulation techniques based on time- and frequency-domain algorithms. For time-domain techniques, important topics such as circuit decomposition, relaxation methods, latency, multirate integration, continuation methods, parallel algorithms, and finite difference time-domain methods are discussed. Frequency-domain simulation techniques included are harmonic balance, harmonic relaxation, harmonic-Newton, spectral balance, methods for quasiperiodic circuits, and device modeling for frequency domain simulators. Also included are examples of modern simulators.
Renewable Energy and the Environment Optics and Photonics Congress, 2012
ABSTRACT Cultural differences in selecting the color quality of illumination were investigated us... more ABSTRACT Cultural differences in selecting the color quality of illumination were investigated using a solid-state source of light with tunable color-rendition properties. The differences were found to depend on the familiarity of illuminated objects.
Unique properties of GaN/AlN/InN heterostructures make them superior for high power applications.... more Unique properties of GaN/AlN/InN heterostructures make them superior for high power applications. The key issues in the device designs are achieving normally-off operation, controlling the electric field distribution in the device channel to prevent breakdown, eliminating or reducing non-ideal effects causing reliability issues, and providing for efficient heat dissipation. High electric fields at the gate edges lead to an additional strain and hot electron effects causing the current collapse and gate lag. Quantum well designs (e.g. incorporating an InGaN or GaN quantum well between the wide band gap AlGaN barrier layer and GaN or AlGaN buffer) might control the wave function penetration and the real space transfer and increase the breakdown voltage. Insulated gate heterostructure HFETs (MOSHFETs) demonstrated superior performance and reliability. Field plates, recessed and double recessed gates, drain field controlled electrodes have been used to control current collapse and impro...
ABSTRACT Mixing of two optical beams with close frequencies in photoconductive structures or thei... more ABSTRACT Mixing of two optical beams with close frequencies in photoconductive structures or their response to ultrashort optical pulses are widely used for the generation of terahertz (THz) electromagnetic radiation. The THz radiation produced by optically excited plasma oscillations in p-i-n structures has been observed by some teams. In this communication, we consider a heterostructure akin to a field-effect transistor with high electron mobility in its two-dimensional channel and report on the modeling of THz oscillations caused by optical signals in this heterostructure. The features of such a heterostructure are associated with the existence of weakly damped electron plasma oscillations and possibility of their resonant excitation, so that the two-dimensional electron channel serves as a resonant cavity with rather high quality factor. A conception of THz photomixing using the excitation of standing plasma waves (plasma oscillations) in the heterostructure under consideration has recently been proposed by the authors. We demostrate that due to the excitation of the electron plasma oscillations in the channel by the photogenerated electrons and holes, the heterostructure in question exhibits a pronounced resonant response leading to high amplitudes of the ac photocurrent oscillations. As shown, this can result in substantially higher efficiency of the THz radiation generation by optical signals than that in p-i-n structures.
We show that the steady state with a dc current in ungated 2D electron gas might exhibit an insta... more We show that the steady state with a dc current in ungated 2D electron gas might exhibit an instability related to asymmetrical boundary conditions, which is similar to the "shallow water" instability in the gated 2D electron gas. The mathematics of the problem corresponds to "deep water" solutions for plasma waves. In the ideal case, the boundary conditions should correspond to zero ac voltage at the source and zero ac current at the drain, similar to the conditions for instability in a field effect transistor. Such boundary conditions can be realized using several different device configurations. For similar device dimensions, the plasma wave generated in an ungated 2D device will have much higher frequency compared to that in gated devices.
... Electron Devices, ED-26, No. 11, pp. 1677-1683, 1979. 2. Lester Eastman, Richard Stall, David... more ... Electron Devices, ED-26, No. 11, pp. 1677-1683, 1979. 2. Lester Eastman, Richard Stall, David Woodard, Niru Dandekar, Colin Wood, Michael Shur and m* = 0.067 r! ' u = 3m /vs/ e / 2 1 / / / / / J = 0.05 x 10 3 A/ cm 2 I 5 6 7 3910 15 20 B (IcGs) Fig. ...
Transferred electron devices can be used as oscillators owing to the negative differential resist... more Transferred electron devices can be used as oscillators owing to the negative differential resistance related to the intervalley transfer of electrons.
The electron density of the two-dimensional electron gas in modulation doped structures is calcul... more The electron density of the two-dimensional electron gas in modulation doped structures is calculated as a function of the doping density in (Al,Ga)As, the thickness of the undoped (Al,Ga)As layer, the lattice temperature, and other device parameters. The results of the calculation show that the depletion approximation is not accurate enough and that the Fermi–Dirac statistics (rather than the Boltzmann statistics) should be used in the calculation. A simple analytical model which takes these factors into account is shown to be in good agreement with our computer calculations and experimental data. The obtained results may be used to evaluate the maximum intrinsic transconductance and the maximum gate voltage swing for the modulation doped field effect transistors.
We demonstrate that the performance of hot-electron transistors and other ballistic devices can b... more We demonstrate that the performance of hot-electron transistors and other ballistic devices can be greatly improved if a focused beam of energetic electrons is injected into the active region of a high-speed device. The results of the Monte Carlo simulations of 72 000 electrons show that the angular distribution of electrons arriving at the collector of a hot-electron transistor is sharper since those electrons injected into the base under large angles primarily contribute to the base current. Our calculations also confirm that ballistic motion may be considerably enhanced by the built-in electric field in the base region. Based on these results, we propose a new device—the double base hot-electron transistor—where the first base acts as an ‘‘electron gun’’ focusing and accelerating the electron beam, which is then injected into the second (active) base where an input signal is applied. Our calculations show that the mean transit time of electrons traversing the active base can be c...
We report on low frequency noise and field-effect mobility in strained-Si surface n-channel metal... more We report on low frequency noise and field-effect mobility in strained-Si surface n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) grown on relaxed virtual substrates with a Ge concentration varying between 0% and 30%. An increased Ge concentration results in higher intrinsic field-effect mobility, increasing from 380cm2V−1s−1 for the unstrained channel to 865cm2V−1s−1 for the strained-Si MOSFET on 30% relaxed SiGe virtual substrate. However, the higher mobility is traded off for increased substrate leakage currents and increased 1∕f (flicker) noise. It is suggested that flicker noise is due to traps in the oxide layer. The density of traps increases from 2×1017eV−1cm−3 for 0% Ge to 2.3×1018eV−1cm−3 for the 30% Ge virtual substrate.
In this paper, compact analytical model for the heterostructure field-effect transistor (HFET) cu... more In this paper, compact analytical model for the heterostructure field-effect transistor (HFET) current-voltage (I-V) characteristics, accounting for the large-signal dispersion, also referred to as current collapse, is presented. The model is based upon an experimentally established fact that the dispersion is mainly due to carrier trapping at the source and drain sides of the gate edges. In wide-bandgap heterostructures like AlGaN/GaN, the characteristic trapping-generation times are several orders of magnitude longer than the signal period at typical operating frequencies. Thus, the radio frequency signal "sees" an averaged I-V characteristic resulting from carrier trapping-generation. The approach, based on this difference, leads to a compact quasi-steady-state analytical model of the HFET I -V characteristics that can be easily implemented in device-circuit simulators. The model shows close agreement with the experimental data
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