Wafer scale processing of InGaAsP/InP lasers

Abstract

Chemically assisted ion beam etching (CAIBE) and electron cyclotron resonance (ECR) plasma deposition have been used to etch and coat 1.3 μm InGaAsP/InP heterostructure lasers in full wafer form. Ar/Cl2 CAIBE, using an ECR dual grid ion source, was used to etch 4 μm deep vertical (90°±0.5°), smooth facets at rates up to 1.3 μm/min. An integrated back facet monitor was simultaneously fabricated in the same heterostructure. High-reflectivity Si/SiO2 optical coatings were deposited on the etched facets by low-temperature (<120 °C) ECR plasma deposition and selectively patterned by liftoff. Full wafer testing of the processed devices showed good uniformity (±3%) with laser threshold currents of 25 mA and a slope efficiency of 0.23 W/A at 25 °C and 0.11 W/A at 85 °C. Back facet monitor efficiency was 0.4 A/W over the whole temperature range.