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Analytical solutions for the forward characteristic of thyristors have been limited to abrupt and constant doping profiles. Average values for the mobilities and the carrier lifetime had to be assumed for each region of the device. Results will be presented here which are based on an exact numerical solution of the transport, continuity, and Poisson equations for the one-dimensional thyristor. Doping, mobility, and lifetime can be varied from point to point. Thyristor structures are much wider and higher doped than the devices treated numerically in the literature. The dependency of the forward characteristic on various device parameters was examined, and the important results were verified experimentally. For high current and a base width that is large compared to the diffusion length, the dependency of mobility on the carrier concentration leads to a base voltage drop significantly lower than that expected from analytical theory. Furthermore, it is shown that for this case the parameters of the highly doped side regions (doping, width, and lifetime) have much less influence than predicted from Herlet's [3] theory.

Experience with beveled p-n junctions does not fully agree with the predictions of Davies and Gentry. Specifically no optimum negative angle as claimed by Huth and Davies was found. A new method for determining the form of the space charge region near the surface shall be presented which avoids the insufficiencies of the model cited. Apart from more accurate results, this paper gives insight into an entirely new phenomenon. In contrast to conventional theory p-n junctions with small negative bevel angles exhibit an absolute electric field maximum underneath the surface. This effect causes a reduction of the breakdown voltage even when the electric field on the surface is sufficiently small. Results will be presented which show the dependency of the absolute field maximum on bevel angle, doping profile and material resistivity. It will be shown that a limit for the use of negative bevel angles exists at about 4 kV breakdown voltage. These theoretical predictions are in excellent agreement with potential probing experiments. Results will also be presented on the influence of dielectrics or charges on the surface.

Infrared microscopy as a means for observing dynamic thermal processes inside a slice out from a silicon power device has been reported by Burtsev et. al. and refined by Jaecklin and Marek. Since the local emissivity depends on doping, instantaneous free carrier concentration and the optics used, interpretation of these radiation measurements is extremely difficult. In the existing literature it has been based on homogeneous emissivity throughout the sample.