Temperature-Dependent Infrared Absorption of Hg-Based II-VI Semiconductor Superlattices

The optical absorption of a series of HgTe/Cd0.85Hg0. 15Te superlattices (SLs) have been measured in the spectral region from 2 to 12 μm at temperatures from 300 K down to 4.2 K. Several subband transitions were identified and their transition energies were compared with theoretical calculations, with the valence band offset ΔEv between HgTe and CdTe as a fitting parameter. It is found that at a given temperature, a value of ΔEv = 420 ± 100 meV fits the results of all the SLs, and ΔEv does not depend on temperature to within ±100 meV.