NUMERICAL MODELING OF ABRUPT INP INGAAS HBTS

High performance heterojunction transistors are expected from a InP/In GaAs system owing to the electrical properties of these materials. In order to understand the physical mechanisms which control the behaviou r of this kind of transistor, a numerical device model has been develo ped. This model combines drift-diffusion transport in the bulk regions with tunnelling and thermionic emission at the base-emitter interface . The electrical characteristics of the above HBT are analysed using t his model. The collector current is dominated by tunnelling transmissi on through the spike appearing in the conduction band. The base curren t is dominated by recombination in the base bulk region, but tunnellin g transport has an additional effect on this current. The maximum unit y-grain frequency is limited by the base transit time.