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edfas.org ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 21 NO. 2 26 effect and those having little effect on the intensity. This can be attributed to the extension of the defect inside the cavity, which is not within reach of the SEM analysis tool. The SEM inspection alsohelped ascertain the presence of organic contamination on the facet surface (Fig. 8). EDX iterative analysis confirmed the presence of meltedmate- rial with silicon traces in most of the CODs. A cathodoluminescence study of the COD was carried out and led to the following conclusions: The area affected by the thermal overstress is larger than the pattern observable under the secondary electron image (Fig. 9). The cathodoluminescence spectra of the COD did not reveal any specific peak, which prevents the possibility of locating the CODs on the component with the aid of single wavelength imagery. CONCLUSIONS During a spacemissionwhere repair is not possible and failure is not anoption, it is important tohave components that not only offer very low statistical risk of failure, but also robustness and resilience. The component passed the qualification tests with success and demonstrated enhanced ruggedness and resilience despite an incident during the test that induced overstressed conditions and some local COD events. Construction analysis and over- stress test failure analysis based on expertise appear to be the best tools to reinforce the qualification outcome. Fig. 8 EDX detection of silicon contaminant mixed into the melted AsGa. Fig. 9 SE and panchromatic cathodoluminescence images and cathodoluminescence spectra of a COD (860 nm for GaAS).