| Summary: | 碩士 === 國立成功大學 === 電機工程研究所 === 83 === GaAs field effect transistors (FETs) utilizing multiple -dopig
profiles grown by low-pressure metalorganic chemicalapor
deposition (LP-MOCVD) have been fabricated successfully.e use
different δ-doping periods and different arrangement of_-doped
layers to get single-graded-like channel, double-graded-ike
channel, and square-like channel. The 2DEG concentrationn
square-like structure can reach up to 2.2x10(13) cm(-2)ithout
degrading electron mobility. The maximum drainurrent density
and maximum extrinsic transconductance inouble-graded-like
structure are 650 mA/mm and80 mS/mm, respectively, at 300 K. In
SGLFET, there arehree peaks in extrinsic transconductance
versus gate voltage.he two maximal transconductance can be
used namely as aouble-mode mixer. Consequently, an improved
gate voltagewing, implying extension of linear amplifier
region, is obtained.hese data prove that multiple δ-doped GaAs
FETs can provideigher performance than single-δ-doped GaAs FET'
s.eanwhile, the double-δ-doped GaAs FET exhibits
highererformance than single-δ-doped GaAs FET's. Besides,inch-
off characteristic can be improved by growing p-layersn the
buffer and under the cap layer.
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