Detection of compositional non-uniformities in InP:Fe via spatially resolved photoluminescence and secondary ion mass spectrometry

Semi-insulating InP wafers for electronic and opto-electronic devices must have spatially uniform resistivities (above 1E7 Omega -cm) for high-yield manufacture. Spatially resolved photoluminescence scans have revealed localized regions of high luminescent efficiency in liquid-encapsulated-Czochralski InP:Fe obtained from two commercial suppliers. These bright spots have dimensions in the micron range, and a density approaching 1E5/cm/sup 2/. Secondary ion mass spectroscopy has shown that the spots contain silicon and iron contaminants. The silicon concentration exceeds 1E20/cm/sup 3/, whereas the iron concentration is 100 times below that of the silicon. A resistivity below 1 Omega -cm would be expected near the spots. These features may generate parasitic capacitance that could affect the yield of integrated circuits and opto-electronic arrays.<
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