Monolithic integration of lasers and bipolar transistors by selective area epitaxy

The authors describe the use of selective area epitaxy to prepare monolithically integrated lasers and heterostructure bipolar transistors (HBTs) based on InGaAs(P)/InP. The laser is a capped mesa buried heterostructure structure grown by metal-organic chemical vapor deposition (MOCVD) and optimized for fiber communications. The HBT structures were grown by metal-organic molecular beam epitaxy (MOMBE) on the semi-insulating current confining layers of the lasers. The quality of selectively grown HBTs is illustrated in the Gummel plot and common emitter output characteristics. The DC performance of an integrated structure is illustrated. The laser is driven with the collector current of the HBT. Threshold is achieved at a base current of I_B=360 μA. Light output of the laser is linear to at least 10 mW. Preliminary experiments show the bandwidth of the integrated device to be in excess of 3 GHz