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.

Thick crack-free CaF2 epitaxial layer on GaAs (100) substrate by molecular beam epitaxy

“…Different maximum crack-free fluoride layer thicknesses have been reported, varying from about 250 to 380 nm. 12 Another reason may include the effect of the cool down time from growth temperature to RT. Schowalter et al 11 found, that, when depositing CaF 2 films on Si substrates, boron contamination in the films from a pyrolytic boron nitride crucible caused film cracking.…”

Progress in Compound‐Semiconductor‐on‐Silicon‐Heteroepitaxy with Fluoride Buffer Layers

“…The highest R0A products for our PbTe sensors on Si now approach 2 9 104 ~cm 2 at 77 K, as high as for the best PbTe sensors on bulk BaF2 (18), or HgCdTe sensors with comparable cutoff wavelengths grown by MBE on CdTe or similar substrates. In addition, we have grown BaF2(100) layers on Si(100) substrates (29).…”