Growth and characterization of AlGaAs/GaAs heterojunction bipolar transistor on GaAs (111)B substrate by molecular beam epitaxy

The growth and fabrication of AlGaAs/GaAs heterojunction bipolar transistors (HBTs) on GaAs (111)B substrate was studied. The surface morphology of (111)B GaAs epilayers strongly depends on the substrate misorientation and substrate temperature. There is only a very narrow window of substrate temperature for the (111)B GaAs growth. It is found that the base leakage current in the low current region can be suppressed by using 2 degrees-off substrates, a precise control of substrate temperature and As/Ga BEP ratio. Additionally, because of the different surface properties along the (111)B direction, the surface recombination current of HBT on (111)B 2 degrees off substrates is smaller than that on (100) GaAs at a growth temperature of 590 degrees C. Copyright (C) 1996 Elsevier Science Ltd