WAFER STAGE STAINING TECHNIQUE FOR DETECTION OF ZN OUT-DIFFUSION IN INGAASP/INP LASERS

We have developed a novel staining technique to detect Zn out-diffusion from the cladding layer into the semi-insulating region in InGaAsP/InP-based laser structures. In this staining technique an Au (400Å thick) coating was applied to InP wafer and an aqueous FeCN solution was used to stain the Au-coated wafer. This technique can clearly resolve the Zn out-diffusion profile in laser structures, and it cannot be achieved by the conventional FeCN staining process. This is the only available technique one can use to detect zinc out-diffusion from the p-cladding layer into semi-insulating InP at the wafer stage and prior to device fabrication. Characterization of zinc diffusion by our technique can provide crystal growers with a timely feedback to further optimize the growth parameters. © 1990, The Electrochemical Society, Inc. All rights reserved.