INTERBAND ABSORPTION AND THE GAMMA-POINT BAND-STRUCTURE PARAMETERS IN HGSE

Optical absorption in HgSe crystals is measured in a wide energy range (0.04 to 0.9 eV). Transmission experiments are carried out at seven temperatures from 10 to 295 K. Very thin samples with electron concentration ranging from 4 × 1017 to 2 ± 1018 cm−3 at helium temperature are used (the absorption coefficient is measured up to 3 × 104 cm−1). Direct optical transitions Γ 6v → Γ 8c, manifesting themselves as a „step” on the absorption curve, are observed at low temperatures. The relationship between the value of the negative energy gap E0 and the value of the spin–orbit splitting Δ is determined from the energy of the front of the „step” as a function of temperature. The absorption coefficient for HgSe is calculated numerically using Kane's formulae for the inverted band structure. The finite value of the spin–orbit splitting Δ and the parameters describing the interactions with „higher bands” are taken into account. A new set of band structure parameters (E0, dE0/dT, P, Δ, A′, L′, M, L – M – N) is obtained. This set can explain the data measured as well as previous experimental results. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA