A study is made of the electrical properties and of the types of structural defects which can occur in epitaxial CaF//2 grown on Si(111) substrates by molecular beam epitaxy (MBE). High-resolution transmission electron microscopy (HRTEM) and high-energy ( greater than equivalent to 2 MeV) He ion channeling techniques are used to characterize defects in the epitaxial layer and at the CaF//2/Si interface while current-voltage (I-V) and capacitance-voltage (C-V) measurements are used to characterize the electrical properties. The HRTEM images show an atomically abrupt interface between the CaF//2 and Si. The most common defect we have been able to identify is associated with an atomic step at the interface and is similar to a Shockley partial dislocation at a (111) twin interface in an fcc crystal structure. The ion channeling measurements also indicate the presence of defects at the CaF//2/Si interface. The apparent defect density measured by ion channeling decreases in the CaF//2 layer as one moves away from the interface at a rate which depends on the final thickness of the epitaxial film. Ion channeling has also been used to measure strain.