p/sup +/-thin surface layer Schottky-barrier enhanced high speed pseudomorphic Al/sub 0.25/Ga/sub 0.75/As/In/sub 0.15/Ga/sub 0.85/As and Ga/sub 0.5/In/sub 0.5/P/In/sub 0.15/Ga/sub 0.85/As MODFETs

In this paper we report on our investigation of the introduction of a highly p-doped very thin surface layer in combination with GaInP as the wide bandgap material in order to improve the breakdown voltage of GaAs based pseudomorphic MODFETs without deteriorating other device performances. In order to proof the quality of this approach we compare the device performance of the new device with that of a conventional AlGaAs/InGaAs MODFET also having a p/sup +/-surface layer. The device performances of AlGaAs/InGaAs and GaInP/InGaAs devices with 1.8 /spl mu/m gate length are, g/sub mmax/=224mS/mm, 200mS/mm, I/sub DSmax/=300mA/mm, 400 mA/mm, V/sub BrDG/ (I/sub G/=1 mA/mm)=10 V, 14 V, f/sub T/=15 GHz, 12 GHz, f/sub max/=59 GHz, 42 GHz, respectively.<
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