CURRENT TRANSPORT IN ALGAAS GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS OPERATING BETWEEN 300 AND 500 K/

The current transport in AlGaAs/GaAs heterojunction bipolar transistor s (HBTs) operating in the temperature range of 300-500 K is investigat ed based on an analytical model including the lattice heating effect. It is found that an uneven increase in the base and collector currents gives rise to the current gain degradation at high temperatures. In a ddition, the study suggests that the effect of lattice heating becomes more important if the HBT area is reduced and/or the ambient temperat ure is increased. Experimental data and results simulated from a devic e simulator are included in support of our finding.