SNDC Multilayer Semiconductor Structures

Abstract

SNDC effects occur in a wide variety of semiconductor junction devices. In particular, we will discuss important cases such as the unijunction transistor (UJT) (Shockley et al., 1949); switchback in a bipolar junction transistor (BJT) (see, e.g., Grove, 1967); the p-n-p-n diode (thyristor or Shockley diode) (see, e.g., Blicher, 1976); the p-i-n diode (see, e.g., Weber, 1970 and Weber and Ford, 1970); the heterojunction hot-electron diode (Belyantsev et al., 1986; Emanuel et al., 1988). All of these have SNDC-type I(Φ) characteristics and are most useful at the lower end of the frequency spectrum. Further, they all involve some form of charge injection. The most useful, interesting, and important of these structures are the p-n-p-n and p-i-n diodes; the p-i-n device will be analyzed in some detail. We will, however, briefly discuss the UJT, BJT, and p-n-p-n structures first. The circuit response for uniform SNDC elements was discussed in detail in Chap. 2. However, when nonuniform current distributions develop a somewhat more complex problem must be solved. We will develop a “two subelement model” approach when we discuss the p-i-n diode; this model applies to devices where single high current density filaments usually dominate, such as some of the electrothermal-type devices discussed in Chap. 8. Shaw et al. (1979) and Solomon et al. (1972) discussed a two subelement model for NNDC devices that form high field domains.