Intraband optical absorption in semiconductor superlattices

Abstract

Absorption coefficients are calculated for intraband (intersubband in the conduction band) optical transition in semiconductor superlattices. The absorption line broadening is introduced by taking the fluctuation of well thickness into account. The selection rule is quite different for two kinds of transitions: transitions from the ground state to states below and above the conduction-band offset. The former follows the usual selection rule, whereas the latter does not. The calculated results well explain the experiments for ${\mathrm{In}}_{0.53}$ ${\mathrm{Ga}}_{0.47}$As/${\mathrm{In}}_{0.53}$ ${\mathrm{Al}}_{0.47}$As superlattices.