We have performed synchrotron radiation photoemission studies of the formation of Hg 1−xCd xTe/metal junctions in the presence of predeposited thin (3–15 Å) Yb layers. Metals examined include Cr, In, and Al. Semi-empirical calculations of bulk binary thermodynamic parameters for each interface suggest that the rare-earth metal should act as an effective diffusion barrier. Correspondingly, we found that Yb interlayers reduce or eliminate metal-Te reaction, Te outdiffusion, and the Hg-depletion of the near-surface region in all cases examined.