Multibandk∙ptheory of carrier escape from quantum wells

Abstract

A general theory of multichannel coherent particle escape introducing the escape matrix based on the scattering formalism has been developed and applied to the problem of hole escape from biased quantum wells. This approach incorporates band-mixing effects, such as valence-band nonparabolicity and heavy-to-light (light-to-heavy) hole transformations, in the theory of carrier escape from quantxum wells consistently with the principles of multiband effective-mass theory. The numerical calculations, made in the Luttinger approximation, show significant influence of the band-mixing effects on the hole escape time and are in satisfactory agreement with available experimental data. The effective decrease of the heavy-hole tunneling mass (``lightening'') as a result of the light-hole admixture is found to be the major reason for the escape-time decrease, as compared to the simple parabolic-band effective-mass model. The concept of the escape matrix can be used for investigating multichannel coherent escape processes in different systems such as quantum wires, quantum dots, or photonic structures.