Gd and Sm interfaces with Hg_1-xCd_xTe(110) and a general model of rare-earth/Hg_1-xCd_xTe(110) interface formation

Room-temperature synchrotron radiation photoemission studies of rare-earth/Hg_1-xCd_xTe(110) junctions were performed as a function of metal coverage for the rare-earth metals Sm, and Gd. These new results are compared to our previous results for Yb/Hg_1-xCd _xTe junctions. At low rare-earth metal coverages, we observe in all cases a rare-earth Te reaction which removes Hg and Cd from the interface region, and the three-dimensional island growth of a rare-earth telluride layer 4.0-4.5 monolayer thick. The most abrupt interface region is observed for Gd/Hg_1-xCd_xTe, in agreement with the more reactive character of this interface as compared to Yb/Hg_1-xCd_xTe and Sm/Hg_1-xCd_xTe. For higher rare-earth metal coverages, we observe the formation of a metallic rare-earth rich layer at the surface, which effectively traps Hg atoms diffusing across the interface through the formation of a rare-earth-Hg alloy.