Investigation of Semi-Insulating SiC Wafers Using Contactless Topographic and Temperature-Dependent Resistivity Analysis
Jantz, Stefan Muller, Rudolf Stibal,
Semimap Scientific Instruments GmbH Tullastr.67 D79108 Freiburg
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Semi-insulating SiC substrates originating from different vendors are analysed with nondestructive techniques. Contactless resistivity mapping (COREMA) provides full wafer images of the resistivity ρ in the range 1x105 – 1x1012 Ωcm. Based on this room temperature precharacterization particular spots on the wafer are selected for measurement of the temperature dependence p(T) to obtain the local carrier activation energy. We find that it varies widely and may be quite different even if values are comparable. Hence both quantities must be measured to obtain a meaningful electrical analysis of semi-insulating SiC. For wafers with persistent conductivity at room temperature the heating curve shows a complex behavior reflecting the heat-stimulated recombination of centers with are persistently ionized at room temperature.
Keywords: Silicon carbide wafers, contactless resistivity mapping (COREMA), resistivity, activation energy compensation process, persistent conductivity