Design and Development of InP DHBTs With High Breakdown Voltage for Ka-Band PA Applications

Type-I (straddled) InP DHBT devices have been fabricated to study the impact of different base-collector junction transition layer designs on the collector to emitter breakdown behavior, breakdown voltage, BVceo and the device output performance such as knee voltage, Vknee at high collector current densities, Jc. An abrupt breakdown behavior with BVceo of 11V and Vknee less than 1V at Jc 100kA/cm
²
are achieved using an optimized base collector junction transition layer design. Using 2D numerical simulations, components of leakages dominating Iceo at low and high collector to emitter bias voltages are explained. It is further shown that the optimized device exhibits good RF and power performance achieving fT of 115GHz and fmax of 150GHz at emitter width 1um. An MMIC power amplifier (PA) is also designed and fabricated using the optimized Type-I InP DHBT device. At 28GHz, good power performance is achieved with PAE of 54% and Psat of 26dBm. Thus, it is shown that InP DHBTs developed in this work are a good candidate for the next phase of 5G millimeter wave Ka-band power amplifier applications.