InP HBT Transferred to Higher Thermal Conductivity Substrate

We report the first demonstration of an InP double heterojunction bipolar transistor (HBT) transferred to a higher thermal conductivity substrate. This process allows lithographic access to both the frontside and backside of the device to minimize parasitic capacitances while transfer to a SiC substrate should reduce junction temperature by 42%, allowing for higher current density operation. The 0.20 × 3 μm² emitter-area HBT has peak common-emitter current gain β = 22 and breakdown V_BR,_CEO >; 4 V. No electrical degradation from the transferred-substrate process is observed. RF measurements show device peak f_τ = 397 GHz, f_max ≥ 400 GHz, and maximum available gain (MAG) at 100 GHz is 15.3 dB.