DESIGN, FABRICATION, AND CHARACTERIZATION OF A HOT-ELECTRON VACUUM TRANSISTOR

The design and fabrication of a vacuum transistor is described which uses hot-electron emission through a thin Schottky metallization as a source of electrons for current flow. A thin titanium metallization on p-type ion-implanted gallium arsenide is used to form a Schottky contact. Application of a reverse bias greater than the avalanche breakdown voltage results in the generation of hot-electrons which are extracted by a collector metallization suspended above the Schottky metal. The collector is fabricated using a standard air-bridge fabrication process which is compatible with standard GaAs monolithic microwave integrated circuit technology. Measurements on fabricated prototype devices confirm a collector current which can be modulated by varying the potential applied to the Schottky metallization and consequently the resulting hot-electron generation. Small-signal modeling suggests that the device can be used for voltage and power gain, although the required load resistances are high for the first-generation prototype devices. This transistor may find application as a high-speed amplifier or in switching circuits for display applications.