Overgrowth of (In,Ga)(As,P) on rectangular-patterned surfaces using gas source molecular beam epitaxy

Integrated optical devices, such as planar waveguide-coupled Bragg-resonant filters, are an important component for the implementation of high density , narrow bandwidth optical filtering in wavelength division multiplexed opt ical communication systems. However, acceptable optical device performance of the filter is contingent upon the ability to maintain the integrity and profile of the as-fabricated rectangular-patterned Bragg resonators during epitaxial overgrowth of the cladding layer. Bragg gratings are defined in b oth InP substrates and InGaAsP epitaxial layers using X-ray lithography and reactive ion etching. The regrowth process is initiated by removing the na tive oxide with a low temperature ( similar to 200 degrees C) atomic hydrog en-assisted cleaning regimen that results in a grating that is unaltered fr om the desired as-etched rectangular-patterned profile. The techniques empl oyed to preserve the grating profile are described, and the microstructural and optical quality of the structures are analyzed via scanning electron m icroscopy, triple axis X-ray diffractometry, and photoluminescence. (C) 199 9 Elsevier Science B.V. All rights reserved.