Degradation of GaAs MESFETS in 18 megohm-cm H2O

Rinsing GaAs MESFETs under illumination in 18 megohm-cm H
2
O is shown to rapidly degrade the dc characteristics of the device. H
2
O etches a trough around the Schottky barrier gate electrode with an etch rate of at least 22 Å/min. Formation of the trough significantly increases the parasitic resistances of the MESFET.