Interband transitions of thin-layer GaAs/AlAs superlattices.

Garriga M., Cardona M., Christensen N.E., Lautenschlager P., Isu T., Ploog K.

Spectroscopic ellipsometry has been used to study the confinement and interlayer coupling effects of the optical interband transitions of (GaAs)m(AlAs)m superlattices. For superlattice periods d>or=50 AA the confinement effect on the E1 transition becomes negligible, whereas on the E0 transition it is still appreciable. For thinner periods, a splitting of the E1 transition, related to interlayer coupling, is observed. The results are compared with photoluminescence measurements. A linear muffin-tin-orbital calculation of the electronic structure of the m=1 superlattice enables us to assign the splitting of the E1 transition to the appearance of two critical points in the Lambda direction as a result of the strong interaction between the folded bands.

Physical Review B, 36 3254-8, 1987.

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