The effect of strain relaxation mechanisms on the electrical properties of epitaxial CaF2/Si(111) heterostructures

A new technique for growth of exactly two monolayers of CaF2 on Si(111) substrates is demonstrated. This technique takes advantage of the tendency of CaF2 to form thick islands at Si step edges on vicinal substrates once a two-monolayer thick wetting layer is deposited. A comparison of I-V characteristics for epitaxial CaF2 layers grown on on-axis versus off-axis substrates demonstrates the advantages of this technique. In addition, preliminary results for electron tunneling through the CaF2 structure is shown using the ballistic electron emission microscopy (BEEM) technique.