Semiconductor optical integrated circuits and method for fabricating the

Abstract

A semiconductor optical monolithic integration device has a semiconductor substrate including an active region and a passive region. Epitaxial layers including a multiple quantum well structure have a variation in band gap energy and thickness along a waveguide direction. The epitaxial layers in the active region are selectively grown by a metal organic vapor phase epitaxy on a first selective growth area defined by a first mask pattern provided in the active region except in the passive region. The first mask pattern has a variation in width along the waveguide direction. The epitaxial layers are simultaneously and non-selectively grown on an entire surface of the passive region by the metal organic vapor phase epitaxy and the epitaxial layers have a mesa structure in the active region and a plane structure in the passive region. A cladding layer having a ridged structure is selectively grown by a metal organic vapor phase epitaxy on a second selective growth area defined by a second mask pattern provided in the active and passive regions. The second mask pattern has a constant width. In the active region, the ridged cladding layer completely embeds the mesa structure epitaxial layers and in the passive region the ridged cladding layer are provided on the plane structure epitaxial layers.