Determination of Semiconductor Parameters and of the Vertical Structure of Devices by Numerical Analysis of Energy-Dependent EBIC Measurements

For a four-layer structure (non-semiconducting layer, upper neutral semiconductor layer, depletion layer, lower neutral semiconductor layer) the EBIC-signal or charge-collection efficiency η, respectively, are calculated as a function of the beam energy E0 or electron range R, respectively, with the corresponding electrical semiconductor quantities for silicon and the respective geometry values as parameters. Some examples are given for which the measured η(E0)-dependences on the basis of the given model curves are fitted by variation of the semiconductor and geometry quantities. The results of a critical analysis of the quantities thus determined are: small diffusion lengths in microscopical volumes can be measured, the vertical structure of semiconductor devices can be investigated, and preparation-related electrically active damaged layers can be detected.