Airbridged-gate MESFETs fabricated by isotropic reactive ion etching

The authors have designed, fabricated, and characterized 0. 1-μm-gate-length MESFETs in which isotropic BCl₃ reactive ion etching is used to remove material under the gate feed to form an airbridge and isolate the active area. This etching is more controllable than wet etch techniques now used. For comparison, conventional mesa-isolated MESFETs were fabricated on the same wafer. By measuring the RF properties at several bias points, fringing capacitances have been extracted. The parasitic capacitances are smaller in the airbridged-gate configuration