Epitaxial growth and characterization of CaF2 on Si

Abstract

CaF2 films have been grown epitaxially on (100) and (111) Si substrates by molecular beam epitaxy. These films have been characterized by electron microscopy, reflection high-energy electron diffraction, Rutherford backscattering ion channeling, and back-reflection Laue x-ray diffraction. In addition, chemical etching has been used to reveal dislocations and to delineate cracks. Film cracking appears to be related to crystalline perfection through misfit dislocation mobility. It is possible to grow high quality, (xmin=3.0%) single-crystal films on (111) Si which are free of cracks and atomically flat. However, the high free energy of the (100) surface in an ionic fluorite crystal prevents the growth of comparable CaF2 films on the (100) Si surface.

Growth kinetics ofCaF2/Si(111)for a two-step deposition

“…3,4 In particular the interface structure was investigated extensively with medium energy ion scattering, 5 x-ray standing waves, 6,7 x-ray photoelectron diffraction ͑XPD͒, 8,9 and x-ray diffraction. [10][11][12] A rough distinction may be made between two different interface structures depending on the growth temperature.…”

STRAIN AND REORDERING IN CaF2/Si(lll) EPITAXY

“…We have reported [4] that high quality epitaxial CaF 2 films can be grown on Si (lll) substrates by molecular beam epitaxy (MBE). Typically, films grown thicker than 200nm exhibit a Rutherford backscattering (RBS) /channeling minimum yield Xmin= 3 .0_0.…”

Substrate Engineering with Fluoride Buffer Layers on Si

“…The crucibles are made of pyrolytic graphite instead of the more common pyrolytic boron nitride(pBN) because it is well known that the fluorides react with the pBN [6]. Figure 1 is a partially exploded view of the K-cell with the major components identified.…”