Far-infrared band and characterisation measurements in the HgTe-CdTe superlattice

Far-infrared (10-250 cm -1 ) reflectivity measurements have been made on three MBE-grown HgTe-CdTe superlattices. Analysis of plasmon effects with a superlattice dielectric function gives the effective mass parallel to the superlattice planes. The low-temperature masses are near those of the Hg 1-x Cd x Te alloy with the same energy gap, suggesting that the superlattice conduction band is like that of the alloy. Comparison of the effective mass values with those calculated from the multiband tight-binding model gives a valence band offset near 350 meV. The infrared data also give accurate values of the layer thickness and composition.