Monolithic integration of AlGaAs/GaAs HBT and GaAs junction-gate floated electron channel field effect transistor using selective MOCVD growth

A novel GaAs BiFET structure based on AlGaAs/GaAs HBT and GaAs junction-gate floated electron channel field effect transistor (J-FECFET) has been developed. Selective metalorganic chemical vapor deposition (MOCVD) growth is extensively used for the BiFET. Structural advantage of the BiFET is that the epitaxial layers of the J-FECFET are identical to the lower part of a conventional heterojunction bipolar transistor (HBT). Transconductance of the fabricated J-FECFET with 1×200 μm² gate is 102 mS/mm with f_T and f_max of 10.7 GHz and 27.3 GHz, respectively. DC current gain of HBT is 21 at a collector current density of 50 kA/cm² with emitter area of 3×2 μm². The new integration technology offer a foundation for development of various multifunction monolithic microwave integrated circuits (MMIC´s).