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

Abstract

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 optical 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 both InP substrates and InGaAsP epitaxial layers using X-ray lithography and reactive ion etching. The regrowth process is initiated by removing the native oxide with a low temperature (∼200°C) atomic hydrogen-assisted cleaning regimen that results in a grating that is unaltered from the desired as-etched rectangular-patterned profile. The techniques employed to preserve the grating profile are described, and the microstructural and optical quality of the structures are analyzed via scanning electron microscopy, triple axis X-ray diffractometry, and photoluminescence.