Light hole interband transitions in HgTe-HgCdTe superlattices

Abstract

The light hole to conduction band optical transition has been identified in the room-temperature absorption spectra of several high quality HgTe-HgCdTe superlattices, in addition to the familiar heavy hole to conduction band transitions. The observation of the light hole transition, coupled with a more accurate determination of the superlattice layer thicknesses, allows the superlattice band gap and the HgTe-HgCdTe valence band offset to be determined more precisely than previously possible. A two-band tight-binding model was used to calculate the transition energies to compare with the optical data. The valence band offset for the HgTe-Hg0.15 Cd0.85 Te interface was determined to be 300±25 meV.