Very short gate-length GaAs MESFET's

GaAs MESFET's with gate lengths ranging from 0.36 µm down to 0.055 µm, the smallest so far reported, have been fabricated using electron-beam lithography. DC output characteristics were obtained from all of the devices tested and transconductances up to 300 mS/mm were measured. However it was observed that there is a maximum drain-source voltage that can be pinched off in these short gate devices. This voltage varies exponentially from 1 V in the 0.055-µm gate devices to 6 V in the 0.36-µm device. It is speculated that this effect is due to current injection into the buffer layer.