Chapter 6 - Hot Electron Transistors

Abstract

An electron moving in the idealized static periodic potential of a crystalline solid might be described by wave vector and energy. The band structure represents the dispersion relation for electrons scattering off the static crystal potential. “Ballistic” electron motion is defined as the transport of a point particle of charge moving through a static crystal potential at the group velocity. Thin-film semiconductor crystal growth techniques, such as molecular beam epitaxy, allow fabrication of atomically precise layered compositional and doping profiles. This chapter discusses the reduction of vertical dimensions in electronic devices such as unipolar and bipolar hot electron transistors. The existence of extreme non-equilibrium or “ballistic” electron transport raises questions concerning the physics of device operation, outside the range of conventional theories. To make useful high-speed devices with small active regions, it would be helpful to have a better understanding of non-equilibrium electron dynamics in the relevant structures.