Synchrotron radiation study of Cd1-xMnxTe (0<= x <= 0.65)

The electronic structure of Cd1−xMnxTe (0≤x≤0.65) has been investigated by photoemission in the photon energy range from 20 to 140 eV. A sharp (≊1 eV full width at half maximum) peak located 3.4 eV below the valence-band maximum (VBM) is assigned to emission from Mn 3d↑ states with e symmetry. The t2 components hybridize significantly with the Te 5p states and contribute therefore nearly uniformly to the top 6 eV of the valence bands. Weak structures below 6 eV of mixed Mn 3d–Te 5p character occur also due to the p-d hybridization. Cd and Te 4d core-level binding energies remain constant over the whole range of Mn concentrations when measured relative to the VBM. This implies that there are negligible chemical shifts and that the VBM is not affected by the replacement of Cd by Mn. The increase in the optical gap with x is thus due to an increase of the conduction-band energy, in agreement with a shift in the Te 4d absorption threshold as measured by partial-yield spectroscopy. A maximum of the Te 5p component in the density of empty conduction states is identified ≊2 eV above threshold. The Mn 3p→3d↓ excitations are atomiclike. The results are interpreted in terms of a schematic linear-combination-of-atomic-orbitals level scheme for the band structure of Cd1−xMnxTe.