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Student paper Effects of Gate Recess Depth on Pulsed I-V Characteristics

Summary: Student paper
Effects of Gate Recess Depth on Pulsed I-V Characteristics
of AlGaNlGaN HFETs
Adam Conway, James Li, Peter Asbeck
University of California. San Diego, La Jolla. CA
This paper reports pulsed I-V characteristics of AlGaNiGaN HFETS fabricated with gate regions
recessed into the AlGaN harrier layer with different recess geometries. Pulsed I-V characteristics
are known to correlate with rf output power measurements vs bias, nnd are an important estimator
of "knee voltage walkout" and "current slump" effects in nitride tIFETs. Our measurements
show that the knee voltage walkout is strongly dependent on the depth of the recessed region, and
that the walkout is minimized in devices with shallower recess depth. The results strongly
support the model that current slump is due to surface traps. An elkclive trap time constant of 10
usec is extracted for these devices.
AIGaN/GaN HFETs have been under intense development for paver amplifier' applications.
Their combination of large channel charge sheet densities, high saturated electron velocity and
high breakdown voltage makes them highly attractive for radar, \vircIess hase station and satellite
communication applications. The potentially very high output po\vcr per unit width and high
efficiency of these devices, however, has typically not been realized in practice due to problems
of anomalous transients in the I-V characteristics, particularly "knee voltage walkout", which
manifests itself as an increase in parasitic resistance when the dcvice is operated at high drain


Source: Asbeck, Peter M. - Department of Electrical and Computer Engineering, University of California at San Diego


Collections: Engineering