Bipolar power semiconductor components. Part 1

To fulfill their conduction function, bipolar semiconductor devices combine electrons and holes. This is in contrast to unipolar devices, in which only one of the two types of carrier carries the current. This is a classic distinction, but one that does not apply well to many modern devices, which combine unipolar and bipolar mechanisms in the same crystal. For this reason, the analysis of the operation of various bipolar power components has been divided into several articles, for reasons of presentation convenience and volume constraints, rather than strict adherence to the principles. The first two articles and are devoted to the study of "pure" bipolar power semiconductors: diode, transistor, thyristor and derived components, while "mixed" components, such as the IGBT (Insulated-Gate-Bipolar-Transistor), are combined with unipolar components, mainly MOS transistors, in the article . Readers will find that this is in fact a set.

For power components, the term bipolar also implies the use of conductivity modulation effects to reduce the on-state waste voltage as much as possible. This conductivity modulation takes place mainly in the wide, low-doped base region that gives the device its voltage-blocking capability. As a corollary, carrier storage weighs on dynamic performance, both on opening and closing. These essential effects are analyzed in this first part, illustrated by the all-important case of the diode which, from both theoretical and practical standpoints, is the archetypal bipolar power component.