PREPARATION OF NIO THIN FILMS AND THEIR USE IN OPTICAL MEASUREMENTS IN VISIBLE AND ULTRAVIOLET

Several methods for producing NiO films for use in optical experiments are discussed including an indication of the significant problems encountered with each method. Transmission spectra between 2000 and 6000 Å are presented for films grown by both electron beam evaporation of nickel in an oxygen atmosphere and by reactive sputtering. The spectra appear to be consistent with one another as well as with the spectra of films grown on MgO by vapor deposition. The transmission spectra indicate that in addition to the absorption edge near 3700 Å, structure is present near 2300 Å. Electron reflection diffraction measurements indicate that films grown by electron beam evaporation and reactive sputtering on CaF2 and LiF have at least some degree of crystalline order. Two films have been used to provide information on the shift of the NiO absorption edge with temperature, the results being -2.9 and -4.2. 10-4 eV/°C. A Kramers Kronig analysis of the reflectivity of bulk NiO has been made and shows that the absorption of the films is consistent with the absorption constant derived from the reflectivity data. The reflectivities of a bulk sample and a film on MgO support the film transmission measurements in indicating structure near 2300 Å. © 1969.