MBE Grown Undoped Superlattice Gate and Modulation-Doped Buffer Structure for Power FET Applications

A new power FET with a hybrid (MESFET and MD) operation mechanism has been fabricated successfully. The insertion of a modulation-doped (MD) structure between the AlGaAs buffer and GaAs active layer gives high output current and high transconductance. By reducing the gate length to 1 µm, transconductance of up to 340 mS/mm can be expected. Furthermore, the use of an undoped AlGaAs/GaAs superlattice “gate insulator” provides low leakage current and much higher gate breakdown voltage (>30 V). From the experimental results, it is obvious that the proposed structure is suitable for high power applications.