Characterization of Copper Iodide Thin Films Fabricated via Laser AssistedMolecular Beam Epitaxy

摘要

For the first time the technique laser assisted molecular beam epitaxy (LAMBE)has been used to fabricate a molecular film by reaction in a molecular beam. Molecular iodine vapor entrained into a stream of helium carrier gas was introduced via a supersonic expansion into the plasma plume of laser evaporated copper to produce copper iodide. Films were deposited on substrates that were situated about 3 cm downstream on the path of the molecular beam. The surface morphology of films depends greatly on the fluence of the incident laser beam and expansion conditions. Films grown at low laser powers show small surface inhomogeneities in their electron micrographs compared to the films that were grown at higher laser powers. Copper in the LAMBE films is found to be mainly in the Cu + state as characterized by electron spectroscopy for chemical analysis (ESCA). A comparison of the surface and structural properties of LAMBE films with that of a vacuum evaporated film suggests both films have similar lattice structures and compositions. It seems that LAMBE can be a powerful technique to deposit novel molecular and composite films for electronics and photonics.