Intersubband and interband optical absorption study of strain-compensated InGaAs-InGaP superlattices grown on GaAs

Strain-compensated In_0.32Ga_0.68As-In_0.32Ga_0.68P superlattices have been grown on semiinsulating [001] GaAs substrates using gas-source molecular-beam epitaxy and their subband structures investigated. Both visible and mid-infrared optical transmission measurements were used to determine the energies of the 1e-2e transitions as a function of superlattice structure. The highest energy 1e-2e transition obtained is 218 meV, corresponding to a wavelength of 5.7 μm. The conduction band offset between the strained In_0.32Ga_0.68As and In_0.32Ga_0.68P appears to lie between 400 and 500 meV.