Collector-assisted operation of micromachined field-emitter triodes

The field at the tip of a field emitter triode can be expressed by E= beta V/sub g/+/sub gamma /V/sub c/, where V/sub g/ and V/sub c/ the gate and collector voltages, respectively. For small gate diameters and tips below or in the plane of the gate and/or large tip-to-collector distances, /sub gamma /V/sub c/<< beta V/sub g/. The-device is operated in the gate-induced field emission mode and the corresponding I-V/sub c/ curves are pentode-like. By increasing the gate diameter and/or recessing the gates from the tips, collector-assisted operation can be achieved at reasonable collector voltages. Results are presented for two devices with gate diameters of 3.6 and 2.0 mu m. By obtaining gamma at different emitter-to-collector distances, I-V/sub c/ and transconductance g/sub m/-V/sub g/ curves are calculated and compared with experimental results. It is shown that as a consequence of collector-assisted operation, the transconductance of a device can be increased significantly.<
>