Inverted-gate field-effect transistors: novel high-frequency structures

The submicrometer inverted-gate GaAs FET (INGFET), which has its gate on the lower plane of the active layer, is simulated using a two-dimensional computer model with energy-dependent parameters. This device possesses equal input and output reactances, which removes the restriction on the transistor width and greatly reduces the parasitic gate resistance. The characteristics of the INGFET are compared with those of the corresponding conventional coplanar MESFET. The INGFET has a higher current-gain cutoff frequency. A traveling Gunn domain is observed for certain bias combinations. Techniques to suppress this domain are discussed. Another novel inverted-gate structure using a space-charge-injection mechanism is simulated, showing the highest transconductance among all the devices studied here.<
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