Quasiparticle lifetime of excited carriers in a semiconductor superlattice.

Abstract

The plasmon spectrum of a semiconductor superlattice with electronic minibands of finite width is intermediate between those of a three-dimensional electron-gas and a periodic array of two-dimensional electron-gas layers. Because the plasmon spectrum is a manifestation of dynamic screening, the quasiparticle self-energy in this system displays novel behavior. A form of the plasmon-pole approximation is used to evaluate the lifetime \ensuremath{\tau} of a quasiparticle with wave vector K=(k,${k}_{z}$). The threshold value ${k}_{c}$ of the parallel component of the wave vector at which the excited electron can begin to emit plasmons varies with ${k}_{z}$, being larger for smaller ${k}_{z}$. The rate of increase of ${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}1}$ above threshold is also larger for smaller ${k}_{z}$.