Title :
Small-signal characteristics of n/sup +/-Ge gate AlGaAs/GaAs MISFET´s
Author :
Fujita, Shuichi ; Hirano, Makoto ; Mizutani, Takashi
Author_Institution :
Electr. Commun. Lab., NTT, Kanagawa, Japan
Abstract :
The small-signal characteristics have been clarified by S-parameter measurements and equivalent circuit modeling. A large intrinsic transconductance of 630 mS/mm and a maximum cutoff frequence f/sub T/ of 70 GHz have been achieved for a MISFET with a gate length of 0.4 mu m. The average electron drift velocity in the channel, evaluated from the f/sub T/, was as high as 1.7*10/sup 7/ cm/s. In obtaining an equivalent-circuit model, a gate conductance parallel to the gate-source capacitance is introduced to take into account the gate forward current of normally-off FETs The gate conductance does not cause the f/sub T/ of the MISFET to deteriorate due to a small gate forward current at a large gate bias, in contrast to GaAs MESFETs.<>
Keywords :
III-V semiconductors; S-parameters; aluminium compounds; equivalent circuits; gallium arsenide; insulated gate field effect transistors; semiconductor device models; solid-state microwave devices; 0.4 micron; 630 mS; 70 GHz; Ge-GaAs-AlGaAs-GaAs; III-V semiconductors; MISFET; S-parameter measurements; electron drift velocity; equivalent circuit modeling; gate conductance; gate forward current; gate length; gate-source capacitance; intrinsic transconductance; maximum cutoff frequence; microwave device; n/sup +/ semiconductor gate; small-signal characteristics; Cutoff frequency; Electrical resistance measurement; Electrons; Equivalent circuits; FETs; Frequency measurement; Gallium arsenide; MESFETs; MISFETs; Scattering parameters;
Journal_Title :
Electron Device Letters, IEEE
