Epitaxial BaF2-CaF2 Stacks on Si(111) and Si(100)

Abstract

AbstractStacks of non lattice matched epitaxial CaF2, SrF2 and BaF2 layers have been grown by MBE onto Si(lll), and, for the first time, onto Si(l00). On CaF2 covered Si(lll) surfaces, BaF2 grows in a 2—d way after formation of the first monolayers despite a lattice mismatch of 14%. On Si(l00), BaF2 grows with the same (100)—lattice orientation as the underlying substrateif at least a thin (=100 Å) intermediate CaF2 layer is deposited first. Growth is 3—d on (100)—surfaces because of the large (100)—surface free energy of the group IIa—fluorides. By applying in situ short anneal cyclesat the first stages of growth, the crystallographic quality increases for (111)— as well as for (100)—orientation.