Pulsed laser deposition of lanthanum sulfide thin films on silicon and indium phosphide substrates: growth, characterization, and field emission properties

The growth, characterization, and field emission properties of pulsed laser deposition of lanthanum sulfide thin films on silicon and indium phosphide substrates were studied. X-ray diffraction analysis of fairly thick films (micrometer size) reveals the successful growth of the cubic rocksalt structure with a lattice constant of 5.863(7) angstroms, which is close to the bulk value. High resolution transmission electron microscope images of the films reveal that they are comprised of nanocrystals separated by regions of amorphous materials. Raman spectra and ellipsometry measurements were also performed. It was found that the work function deduced from Fowler-Nordheim plots at room temperature has a mean value of 0.65 eV. Also, a strong dependence of the field emission current with temperature was observed.