Published online by Cambridge University Press: 26 February 2011
The evaporation and epitaxial growth on single crystal CaF2 substrates of CaF2/SrF2 mixtures are investigated. The evaporated films are studied with X-ray diffraction and optical microscopy.
X-ray diffraction results show that the evaporation of yCaF2 + (1 - y)SrF2 mixtures from a single boat, with y in the range 0 to 1, result in single phase, mixed crystals of composition CaxSr1−xF2. If Vegard's law is assumed to apply it is found experimentally that the film composition is the same as that of the source.
For the evaporation of CaF2 and SrF2 onto cleaved CaF2 crystals it is shown that the best quality epitaxial films are obtained at substrate temperatures of∼400°C. At temperatures <400°C there is some broadening of the X-ray diffraction spots from the overlayer compared with those from the substrate. At temperatures>400°C there is a tendency for the epitaxial films to delaminate from the substrate.