Thin and ultrathin films of palladium oxide for oxidizing gases detection

Abstract Thin and ultrathin films of palladium oxide are set forth as promising materials for oxidizing gas detection. Thin and ultra thin PdO films were prepared by thermal oxidation at dry oxygen of previously formed Pd layers on polished poly-Al 2 O 3 , SiO 2 /Si (100), optical quality quartz, and amorphous carbon/KCl substrates. By high-resolution transmission electron microscopy and high-resolution scanning electron microscopy it has been found that thickness was about 5–10 nm and 30–35 nm for ultrathin and thin PdO films, respectively. By high-energy electron diffraction and X-ray analysis it has been established that oxidation of initial Pd layers at T  = 770–1070 K led to formation of homogenous polycrystalline PdO films. At ozone and nitrogen dioxide detection PdO films prepared by oxidation at T  = 870 K have shown the good values of sensitivity, signal stability, operation speed, and reproducibility of sensor response. In comparison with other materials, palladium oxide thin and ultrathin films have some advantages at gas sensor fabrication. Firstly, at rather low operating temperatures PdO films have shown good values of functional parameters. Secondly, the synthesis procedure of binary PdO films is rather simple and is compatible with planar processes of microelectronic industry.