Modulation-Doped In 0.5 Al 0.5 P/GaAs Field-Effect Transistors

In 0.5 Al 0.5 P/GaAs modulation-doped field-effect transistors (MODFETs) have been fabricated to study the applicability of In 0.5 (Ga 1- x Al x ) 0.5 P/GaAs heterostructures to electronic devices. A DC transconductance of 250 mS/mm and a noise figure of 1.7 dB with associated gain of 10 dB at 12 GHz were obtained for a MODFET with a 0.25 µm-long and 200 µm-wide gate. Improvements in the performance are expected by Al-composition optimization for the InGaAlP. These results show the promising potential of In 0.5 (Ga 1- x Al x ) 0.5 P/GaAs MODFETs as high-frequency and high-speed devices.