Surface recombination mechanism in graded-base InGaAs-InP HBTs

The surface recombination at extrinsic base region in graded-base InGaAs-InP heterostructure bipolar transistors (HBTs) is studied. The (NH/sub 4/)/sub 2/S treatment eliminates the surface recombination, seen from the size-independent current gain. The surface recombination currents of the selfand nonself-aligned HBTs have different behavior. The mechanism of it is discussed.