Structural, optical, and electrical properties of Pb1−xYbxTe films (0<x<0.25)

We present the structural, optical, and electrical properties of Pb1−xYbxTe films (0<x<0.25) obtained by coevaporation onto Vycor, NaCl, and BaF2 substrates. They crystallize in the NaCl-type structure. The lattice parameter decreases slowly as x increases, not obeying the Vegard’s law. Our data seem to indicate the stability of Yb2+ for 0<x<0.25. The optical band gap increases linearly with x. The resistivity of the films (n type) increases slowly whereas the mobility (135 cm2/V s for x=0.008) decreases faster as x increases.