Buried Waveguides using a Quasi-Planar Process
Résumé
The oxidation of Al-containing III-V semiconductors is an established technology to selectively transform a high-index (2.9) semiconductor layer into an insulating low-index (n~1.6) aluminium oxide (AlOx) and which, thereby, allows the fabrication of buried oxide apertures in either vertical-cavity surface-emitting lasers or waveguide-based devices [1-4]. Because of the chemical selectivity of the process, the oxidation is conventionally carried out as a lateral oxidation from the sides of etched mesas (see Fig. 1 left), resulting in a loss of wafer planarity which, in turns, renders the subsequent fabrication stages of waveguide devices more complex. In this paper, we report the first demonstration of an alternative technique to make buried optical waveguides where the oxidation is carried out through via-holes (see Fig. 1 right) leading to a quasi-planar approach.