InP Schottky-gate field-effect transistors.

MESFET's with gates 1 micron long were fabricated in LPE layers of InP on Cr-doped InP substrates. The devices have current gain cutoff frequencies of 20 GHz or somewhat larger. This value is greater than that of the best analogous GaAs MESFET by a factor of 1.5. The highest power gain cutoff frequency for the InP device is 33 GHz, which is somewhat smaller than that of the best analogous GaAs device. The lowest minimum noise figure at 10 GHz for these first InP devices is 3.9 dB with an associated gain of 4.8 dB. The best result for the GaAs counterpart is 3.2 dB with an associated gain of 7.8 dB. The power gain of the InP device suffers compared to the GaAs device because of degenerative feedback resulting from a large gate-to-drain capacitance and because of a small output resistance.