In this paper, a high-efficiency and compact AlGaN/GaN heterojunction field-effect transistor (HFET) power amplifier integrated with a microstrip antenna at 7.25 GHz is presented for RF front-end circuit applications. A microstrip circular sector antenna is employed as both a radiator and frequency-dependent output load. Higher order harmonics from the HFET in nonlinear operation are reactively...

We propose in this paper a three-dimensional finite element based heat transfer model for a Gallium Nitride-based Heterostructure Field-Effect Transistor (henceforth referred to as GaN HFET). Analyses were carried out to study the distribution of temperature in the HFET under steady state conditions for two different steady-current inputs. Two different substrates for the HFET, sapphire and sil...

Extremely high cut-off frequencies (1) with excellent noise performance demonstrate the capability of heterostructure field-effect transistors (HFET) based on the InAlAs/InGaAs/InP material system for microwave communication systems and for opto-electronic applications. But, due to the low energy band-gap of the channel material, at high drain-source-voltages VDS impact ionization in the channe...

NEDO’s Japanese national project on high power and high frequency nitride device is overviewed. Studies on correlation between crystal defects and device performances, electric field and thermal distribution in the device under operating conditions are demonstrated. Excellent CW RF output power of 230 W from a single chip and 371 W peak saturation power from an amplifier composed of paralleled ...

tion as an alternative to Si as a semiconductor material for ultra-low-loss power devices. Early development of GaN was carried out in the area of light-emitting devices—green LEDs, lasers, etc.—but its superior performance as noted above and the needs of society led to R&D work for electronic devices being conducted world-wide. Specifically, the AlGaN/GaN HFET structure permits the formation o...

Too often the identification of critical road sites is made by “accident-based” methods that consider occurred accidents’ number. Nevertheless, such a procedure may encounter some difficulties when an agency does not have reliable and complete crash data at site level (e.g., accidents contributing factors clear or approximate accident location) crashes are underreported. Furthermore, relying on...

Gate leakage currents in AlGaN/GaN heterostructure field-effect transistor ~HFET! structures with conventional and polarization-enhanced barriers have been studied. Comparisons of extensive gate leakage current measurements with two-dimensional simulations show that vertical tunneling is the dominant mechanism for gate leakage current in the standard-barrier HFET and that the enhanced-barrier s...

Abstract We have investigated photon-assisted trapping and detrapping of electrons injected from the gate under negative bias in a heterostructure field-effect transistor (HFET). The electron injection rate was found to be dramatically affected by sub-bandgap laser illumination. trapped reduced two-dimensional gas (2DEG) density at AlGaN/GaN heterointerface but could also emitted their trap sta...

We have carried out an experimental study revealing that velocity saturation (usat) occurring in both the extrinsic source and drain sets a fundamental limit on maximum drain current and useful gate swing in HFET’s. Using AlGaAsl n f InCaAs HFET’s as a vehicle, we find that first gm and eventually f~ decline at high currents in two stages. Initially, the approach of vsat in the extrinsic device...

This paper describes an 84-116 GHz Nb/Al-oxide/Nb SIS mixer with multi-octave IF bandwidth and quantum-limited sensitivity. The mixer can be integrated with a three-stage 4-12 GHz HFET preamplifier or fitted with a coaxial connector for operation with an external isolator and IF amplifier. An 84-116 GHz receiver using the mixer with an integrated 4-12 GHz HFET preamplifier has a double sideband...