Investigation of emitter current crowding effect in heterojunction bipolar transistors

The emitter current crowding effect in heterojunction bipolar transistors (HBTs) has been investigated using a specific test device. This test device, which is a heterojunction bipolar transistor with two separate base fingers, also allows evaluation of the HBT base resistance. By using of this test device, the authors demonstrate that a 3 mu m large HBT does not exhibit the emitter current crowding effect. An analysis of the saturated regime is also presented.