Optical waveguides and SIMOX characterisation

Summary form only given. For the study of optical waveguide attenuation, CVD is used to provide a surface oxide. Two types of SIMOX wafers were examined. In the first an uninterrupted 150-keV implant to a total dose of 1.7×10¹⁸ cm^-1 was used. This was subsequently annealed at 1250°C for two hours. The measured optical losses turned out to be disappointingly large at ~30 dB cm^-1. A second wafer was similarly implanted to 1.7 10¹⁸ cm^-2, but the implantation energy and the annealing were increased to 180 keV and 1325°C (2 hr), respectively. Despite these seemingly favorable changes the losses remained high at comparable levels. SIMOX wafers produced by a sequence of implant-annealing steps were also evaluated for guiding. The first of such wafers examined was implanted at 160 keV in three stages to a total dose of 1.2×10¹⁸ cm^-2. The two intermediate and final annealing steps were all at 1300°C. The optical losses were substantially reduced to ~4 dB cm^-1. A second wafer that was sequentially processed in a similar manner was also examined. In this instance an epitaxial layer was also grown. The extra thickness allowed a thermal oxide rather than a deposited oxide to be used for the guiding structures