Sub-Micrometer InP/InGaAs Heterojunction Bipolar Transistors with fT = 400 GHz and fmax > 500 GHz

We report InP-based double heterojunction bipolar transistors (DHBTs) with emitter widths of 0.25 mum and RF performance of f_T = 400 GHz and f_max >500 GHz. The HBT structure consists of an InP emitter with an abrupt emitter-base interface, a 300 compositionally graded InGaAs base region, and a 1200Aring collector. The scaled devices reported here have been integrated with a planar, multi-level interconnect process to produce static divide-by-2 circuits with maximum input frequencies greater than 150 GHz and small DDS circuits with output f_clock up to 21 GHz. We believe that the device and interconnect technology reported here represents a combination of performance and integration suitable for future digital and mixed-signal applications while maintaining the manufacturability required for large circuit yield