1.55-μm multiple-quantum-well laser and heterojunction bipolar transistor fabricated from the same structure utilizing zinc diffusion

Abstract

In this paper we demonstrate a novel concept for the fabrication of devices for optoelectronic integration, utilizing Zn diffusion. A multiquantum well (MQW) laser and a heterojunction bipolar transistor (HBT) was fabricated from the same epitaxial structure. We investigated the diffusion properties of zinc into InP with n-type background doping using the open tube technique. General design issues for the common epitaxial layer structure are discussed, and an epitaxial structure is proposed where the top separate confinement heterostructure (SCH) of the laser and the base layer of the HBT are the same, and the active region is placed in the collector of the HBT. Large area HBTs were fabricated from the as-grown material and dc current gains (beta) of 500 was obtained. Diffusion was used to convert the top layers from n to p on as-grown material, and FP ridge waveguide lasers were fabricated from that material. They show a room temperature cw threshold current of 19 mA, and a differential quantum efficiency of 25%. High frequency measurements were performed and a 3 dB limit of 12 GHz was obtained.