1. General

To withstand high voltages, a relatively large, low-doped region must adjoin the blocking junction of the semiconductor device, to allow the space charge zone to expand sufficiently. This region, generically referred to as the "base", forms the core of power devices. The "base" is often homogeneous, N-type in preference to P-type, for reasons of electron mobility or technological imperatives. It forms the central region of diodes and rectifiers, the N-base of thyristors and IGBT transistors, the collector region of bipolar transistors (although it originally corresponded to the base of "alloy" transistors), and the drain region of power MOS transistors. Depending on the structure of each of these devices, the base is bounded, opposite the blocking junction, by a more heavily doped region of the same or opposite type. Typical profiles to be considered when studying the voltage withstand...