PREPARATION AND CHARACTERIZATION OF CRYSTALLINE ZRC FILMS

The characterization of the surface properties of ZrC films grown by thermally evaporating ZrC onto room temperature W(100) and W(110) and then annealing, are reported. These films as deposited have no long range order as determined by low energy electron diffraction, but heating to above 1800 K produces well-ordered layers. During annealing the ZrC(100) face forms on W(100), and the ZrC(111) face forms on W(110). Work functions as low as 2.75 eV have been measured on these films after initial heating, but final values are 3.8 5 eV for ZrC(100), and from 4.40 to 4.80 eV for ZrC(111), depending on the C contamination of the W(110) substrate. From thermal desorption spectra desorption energies were also calculated. Possible mechanisms for the ZrC crystalline ordering during annealing are discussed.