Fabrication of a 1.55-μm VCSEL and an InGaAsP-InP HBT from a common epitaxial structure

A common epitaxial structure is used for the fabrication of a 1.55-μm vertical-cavity surface-emitting laser and an InGaAsP-InP heterojunction bipolar transistor (HBT). By selectively applying zinc diffusion directly after growth, the doping type of the HBT cap and emitter is reversed, providing the epitaxial material used for the laser. This enables a similar process to be used for the two devices. Fabricated HBTs show a current gain of 400 at a collector current of 20 mA. Lasers are electrically pumped and operate continuous wave up to -70/spl deg/C.