IN-SITU FOCUSED ION-BEAM IMPLANTATION FOR THE FABRICATION OF A HOT-ELECTRON TRANSISTOR OSCILLATOR STRUCTURE

Recent advances using in situ focused ion beam implantation during an MBE growth interruption have been exploited to fabricate planar GaAs h ot electron structures without the need for shallow ohmic contacts. Th is novel fabrication route shows a very high yield and has been used t o demonstrate a prototype high-frequency oscillator structure based on electron multiplication in the base layer. Existing devices show tran sfer factors in excess of unity as well as reversal of the base curren t at high injection levels, which are the prerequisites for oscillator action. Future improvements in device design are discussed.