Vertical integration of an InGaAs/InP HBT and a 1.55 µm strained MQW p-substrate laser

An InGaAs/InP heterojunction bipolar transistor has been vertically integrated with a 1.55 µm strained MQW p-substrate laser. The laser exhibits a room temperature CW threshold current of 6 mA, and a DC current gain exceeding 50 is obtained for the HBT. The integrated device shows an ‘effective threshold current’ (base current) of 130 µA and a slope efficiency with respect to the base current of 10 mW/mA. The magnitude of the optical feedback from the laser to the HBT, due to spontaneous and scattered stimulated emission, has also been determined.