PULSED LASER ATOM PROBE CHARACTERIZATION OF SILICON CARBIDE

Field-ion microscopy and field evaporation of α-SiC and β-SiC materials have been successfully demonstrated. Since field-ion micrographs could be taken immediately after pulsed field evaporation, the effects of preferential field evaporation of silicon that occurred under ramped field evaporation were eliminated. However, due to the high electrical resistivity of silicon carbide, conventional voltage pulsed field evaporation was not practical and pulsed laser field evaporation was required. No significant variations in performance were found as a function of laser wavelength but the full-width-at-half maximum mass resolution of 0.4 amu was inferior to voltage pulsed field evaporation of metals. In addition, the background noise level was considerably higher. Within the statistical accuracy of the analyses, the compositions were found to be slightly deficient in silicon. These experiments also revealed that the laser power required to field evaporate SiC was greater than for other semiconducting materials