OZONE-ENHANCED MOLECULAR-BEAM DEPOSITION OF NICKEL-OXIDE (NIO) FOR SENSOR APPLICATIONS

For the deposition of nickel oxide (NiO) a molecular beam deposition p rocess in an ozone atmosphere was developed. Purl gaseous ozone is rec eived from a cooling system, which stores only O-3 at -78 degrees C fr om a O-2/O-3 gas mixture stream, created with an ozone generator. The ozone is released by heating up the system to room temperature. For th e deposition process nickel is evaporated while a constant ozone parti al pressure is adjusted in the growth chamber. The reactive species of ozone reacts on the substrate surface with the impinging metal atoms to form the compound. This process was carried out in an ultra high va cuum (UHV) chamber to create pure nickel oxide films at room temperatu re and to study the fundamental layer properties for sensor applicatio ns. These films were characterized with respect to their stoichiometri c and optical properties by Auger Electron spectroscopy and ellipsomet ry. The gas sensitivity of the films (as deposited and annealed) on va rious gases (H-2, NH3, NO2, SO2, CO) was investigated by work function measurements. (C) 1997 Elsevier Science S.A.