Photoemission studies of core level shifts in HgCdTe, CdMnTe, and HgZnTe

The results of photoemission studies of core level shifts in the Hg(1-x)Cd(x)Te, Cd(1-x)Mn(x)Te, and Hg(1-x)Zn(x)Te alloys are discussed. In Hg(0.7)Cd(0.3)Te, the Hg 5d level is found to shift to lower binding energy by 0.1 eV, and the Cd 4d level to shift to higher binding energy by 0.25 eV upon alloying (relative to their binaries). The Born-Haber cycle is used to determine core level binding energies relative to the valence-band maximum in the context of tight-binding theory, and calculated core level shifts upon alloying in HgCdTe are shown to be too small to account for the observed values. A natural valence-band offset between HgTe and CdTe of 0.35 eV is found.