On the characterization of electrically active inhomogeneities in semiconductor silicon by charge collection at schottky barriers using the SEM-EBIC (II). Contrast due to defects

The influence of the control variables (E₀, I_b, U_r) as well as the semiconductor parameters (ϱ, L) on the defect contrast of direct irradiated Schottky barriers is investigated. The resolution of the subsurface regions is enhanced by increasing the primary beam energy E₀. The sharply imaged region can be extended into the depth of the crystal by applying a reverse bias U_r. Contrast width broadenings are observed in high-ohmic material, if increasing the beam current I_b, which may be annuled by switching on U_r. Against the generally held view the diffusion-induced contrast width broadening of defects (or parts of them) located outside the depletion layer was found as an extremely small fraction of the diffusion length L. Thus in rough approximation the contrasts can be interpreted as a superposition of the in general club-shaped generation volume and the defect shape.