Growth of lattice-mismatched stacked epitaxial CaF2-SrF2-BaF2 layers on (100) oriented Si substrates

Abstract

(100) oriented BaF₂ has been grown epitaxially onto Si(100) despite its large lattice mismatch of 14% and preferred (111) growth mode. (100) epitaxy was achieved using thin intermediate CaF₂ and/or SrF₂ buffers to overcome the mismatch in a stepwise manner. Growth is three dimensional, and a roughness of the top surface in the 10 nm range was obtained. Ion channeling minimum yields are below 4% even for layers as thin as 3000 Å. Thermal misfit strains relieve due to movement of misfit dislocations. The layers are intended for use as epitaxial buffers for growth of compound semiconductors on Si(100) substrates with up to 20% total lattice mismatch.