Properties of NaCl films grown on Ge substrates in ultra-high vacuum

The dielectric properties of thin films of NaCl have previously been studied by Weaver¹ and Macfarlane and Weaver.² This work was carried out in a relatively poor vacuum and the films were deposited on amorphous substrates. There is a need to extend the research on alkali halide films deposited under clean ultra-high-vacuum conditions. Also, it would be advantageous to deposit the films on heated single-crystal substrates in the anticipation of producing epitaxial films, and thereby removing any speculation as to the effects of grain boundaries. In fact, Ge provides a suitable substrate, since the lattice constants of NaCl and Ge are exactly matched at 99.4°C.