X-RAY ABSORPTION NEAR EDGE STRUCTURE ANALYSIS OF HgMnSe, HgFeSe AND HgTeSe *

Experimental studies of the Se K X-ray absorption edges have been carried out in HgTe0.5Se0.5, Hg0.8 Mn0 .2 Se and Hg0.9Fe0.1Se. A comparison is made for Hg0.5Mn0.5Se and Hg0,5 Fe0,5 Se theoretical results obtained by the self-consistent, semi-relativistic LMTO method within the LD approximation. Small differences of Se K edge XANES have been shown for HgTeSe and HgSe in contrary to evident differences for HgMnSe and HgFeSe. This behaviour of the absorption Se K edges is related to significant, hybridized contribution of the 3d and 4s Mn or Fe unoccupied states. The maximal contributions of the hybridized bands of the hypothetic zinc-blende MnSe or FeSe were estimated using the virtual crystal model. These maximal contributions are situated at about 6 eV and 17 eV in zinc-blende MnSe and at -0.8 eV and 5.5 eV in zinc-blende FeSe. For HgFeSe apart from the evidence of the strongly localized resonant donor (empty for low Fe concentrations) the complementary hybridized contribution of Fe 3d empty states also situated around the conduction band minimum should be taken into consideration.