A. Zeng et al., ELECTROOPTIC CHARACTERIZATION OF MODULATION-DOPED FIELD-EFFECT TRANSISTORS WITH MONOLITHICALLY-INTEGRATED TEST FIXTURES, Optical and quantum electronics, 28(7), 1996, pp. 867-874
The authors report on the fabrication and electrooptic measurement of
modulation-doped field-effect transistors (MODFETs) monolithically int
egrated with coplanar stripline fixtures incorporating photoconductive
switches. Both lattice-matched devices on InP substrates and pseudomo
rphic devices on GaAs substrates, as well as two different gate access
structures have been characterized. In comparing two devices with ide
ntical gate access structures, one finds that the delay time of the ps
eudomorphic device is almost twice as long as that of the lattice-matc
hed device. Surprisingly, the switching times (drain output risetimes)
of the two devices are comparable. One also sees that the gate access
structure significantly affects the switching in two lattice-matched
devices: the switching times for double-gate and single-gate contact d
evices are 4.2 and 5.2 ps, respectively. In this case, however, no dif
ference was seen in the delay times. These results show that, for the
present devices, the switching and delay times are dominated by differ
ent mechanisms.