43,917 research outputs found
Gyrator employing field effect transistors
A gyrator circuit of the conventional configuration of two amplifiers in a circular loop, one producing zero phase shift and the other producing 180 deg phase reversal is examined. All active elements are MOS field effect transistors. Each amplifier comprises a differential amplifier configuration with current limiting transistor, followed by an output transistor in cascode configuration, and two load transistors of opposite conductivity type from the other transistors. A voltage divider control circuit comprises a series string of transistors with a central voltage input to provide control, with locations on the amplifiers receiving reference voltages by connection to appropriate points on the divider. The circuit produces excellent response and is well suited for fabrication by integrated circuits
Aluminum nitride insulating films for MOSFET devices
Application of aluminum nitrides as electrical insulator for electric capacitors is discussed. Electrical properties of aluminum nitrides are analyzed and specific use with field effect transistors is defined. Operational limits of field effect transistors are developed
High intensity study of THz detectors based on field effect transistors
Terahertz power dependence of the photoresponse of field effect transistors,
operating at frequencies from 0.1 to 3 THz for incident radiation power density
up to 100 kW/cm^2 was studied for Si metal-oxide-semiconductor field-effect
transistors and InGaAs high electron mobility transistors. The photoresponse
increased linearly with increasing radiation power up to kW/cm^2 range. The
saturation of the photoresponse was observed for all investigated field effect
transistors for intensities above several kW/cm^2. The observed signal
saturation is explained by drain photocurrent saturation similar to saturation
in direct currents output characteristics. The theoretical model of terahertz
field effect transistor photoresponse at high intensity was developed. The
model explains quantitatively experimental data both in linear and nonlinear
(saturation) range. Our results show that dynamic range of field effect
transistors is very high and can extend over more than six orderd of magnitudes
of power densities (from 0.5 mW/cm^2 to 5 kW/cm^2)
Field effect transistors improve buffer amplifier
Unity gain buffer amplifier with a Field Effect Transistor /FET/ differential input stage responds much faster than bipolar transistors when operated at low current levels. The circuit uses a dual FET in a unity gain buffer amplifier having extremely high input impedance, low bias current requirements, and wide bandwidth
Vertical field-effect transistors in III-V semiconductors
Vertical metal-semiconductor field-effect transistors in GaAs/GaAlAs and vertical metal-oxide-semiconductor field-effect transistors (MOSFET's) in InP/GaInPAs materials have been fabricated. These structures make possible short channel devices with gate lengths defined by epitaxy rather than by submicron photolithography processes. Devices with transconductances as high as 280 mS/mm in GaAs and 60 mS/mm (with 100-nm gate oxide) for the InP/GaInPAs MOSFET's were observed
Energy dissipation in graphene field-effect transistors
We measure the temperature distribution in a biased single-layer graphene
transistor using Raman scattering microscopy of the 2D-phonon band. Peak
operating temperatures of 1050 K are reached in the middle of the graphene
sheet at 210 KW cm^(-2) of dissipated electric power. The metallic contacts act
as heat sinks, but not in a dominant fashion. To explain the observed
temperature profile and heating rate, we have to include heat-flow from the
graphene to the gate oxide underneath, especially at elevated temperatures,
where the graphene thermal conductivity is lowered due to umklapp scattering.
Velocity saturation due to phonons with about 50 meV energy is inferred from
the measured charge density via shifts in the Raman G-phonon band, suggesting
that remote scattering (through field coupling) by substrate polar surface
phonons increases the energy transfer to the substrate and at the same time
limits the high-bias electronic conduction of graphene.Comment: The pdf-file contains the main manuscript (19 pages, 3 figures) and
the supplement (5 pages, 4 figures
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