Excitons and interband transitions in III-V semiconductor superlattices

The fundamental optical absorption of ${\mathrm{In}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ga}}_{\mathit{x}}$As/${\mathrm{In}}_{1\mathrm{-}\mathit{y}}$ ${\mathrm{Al}}_{\mathit{y}}$As and GaAs/${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Al}}_{\mathit{x}}$As superlattices is calculated quantitatively using superlattice K⋅p theory. Electron-hole Coulomb interactions yielding excitons and interband-transition Sommerfeld enhancement are incorporated. These fast, nonvariational calculations yield optical structure within 2–3 meV and absolute absorption coefficients within 10% of experimental results for all but one of the twelve samples analyzed. Constituent bulk parameters and band offsets constitute the only input. Computer requirements are very modest. Calculations for different band offsets and other interface parameters using this versatile approach permit estimates of physically important quantities of relatively unexplored heterostructure systems, for example, II-VI superlattices.