Scanning Microscopy


Cathodoluminescence contrast from defects with different geometrical and electronic properties have been studied using the numerical model developed in Part I. The contrast of a localized subsurface defect exhibits a maxima at a specific beam energy Emax which corresponds to the depth of the defect. The contrast of a dis-location which intersects the top surface perpendicularly is a decreasing function of beam energy. The differences in the image profiles of the two different kinds of defects allow the two types of imperfections to be distinguished. In addition, the resolution of a subsurface defect at beam energies lower than Emax is only a function of defect size and is insensitive to the defect strength. The defect depth, size and strength can therefore be extracted sequentially. The extension of the model to the investigation of complex or multiple defects such as "dot and halo" contrast is also illustrated.

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