Phonon-assisted tunnelling

Abstract This chapter discusses the roles of phonon-assisted tunnelling and, to a lesser extent, phonon scattering, in two related types of low-dimensional semiconducting structures: resonant tunnelling devices and superlattices (phonon-assisted tunnelling effects in quantum dots are discussed in Chapter 4). Phonon-assisted tunnelling describes the process in which electron or hole tunnelling is accompanied by the emission or absorption of a phonon. Phonon-assisted tunnelling by longitudinal optic phonons gives rise to satellite lines in the I(V) characteristic of the device. However, phonon-assisted tunnelling by acoustic phonons can only be seen as a change in I(V) produced by a change in the phonon occupation number, such as that resulting from an incident heat pulse. The chapter also includes brief descriptions of work on coherent phonon generation from superlattices, on the effect of surface acoustic waves on single electron transport in quantum wires, and on the role of phonon-assisted tunnelling in quantum cascade lasers.