Build‐up and decoherence of optical transients in disordered semiconductors

Abstract

For a model two-band semiconductor with static disorder, suddenly illuminated by intense light, the averaged non-equilibrium Green function can be obtained within the coherent potential approximation. Explicit solutions found previously are analyzed on numerical examples of the transient photoexcited distribution. The results are used to test the semigroup property 'of the propagators and the analogous factorization of the particle correlation function known as the generalized Kadanoff-Baym ansatz. Both properties hold much better if quasiparticle states are used instead of the bare particles. The quasiparticle modification of the ansatz is motivated formally and verified on numerical data.

Dynamics of mesoscopic systems: Non-equilibrium Green's functions approach

“…Such procedure is barely uniquely defined, but we will outline in more detail one possibility. A natural guess for QKBA (written in resemblance with (25)) is (27) where G R Q denotes a quasi-particle propagator -unspecified as yet. In the two sub-sections to follow we will give Eq.…”

“…The source term, with the true propagator G R replaced by G R W , is identical with the t > t half of QKBA shown in (27) , but with the optical potential σw not specified so far:…”

“…This Ansatz has been modified to a class of the socalled causal Ansatzes including a particularly successful Generalized Kadanoff-Baym Ansatz [25,26,[8][9][10]. We will describe an improved version we call QuasiParticle Kadanoff-Baym Ansatz [27,10,28]. It is based on the notion of non-equilibrium quasi-particle whose meaning will be given in some detail.…”

Ultrafast Dynamics and Quantum Transport of Electrons in Strongly Disordered Semiconductors

“…In this contribution, we test this GKBA against a model soluble directly for the NGF. Such model of a non-equilibrium transient, involving only alloy scattering, treated in the coherent potential approximation (CPA) was introduced in [3,4].…”

“…It provides the particle number conservation. The equation was solved in [3,4] using Fourier transformation and calculating Σ< (z) (z is complex energy) by means of the usual CPA (see [8]). …”