Effect of Gold Addition on Electrical and Optical Properties of NiO Films by Rf Sputtering
The NiO-Au composite films with Au contents of 0 to 33.7 at.% are deposited on glass substrates. The high electrical resistivity (ρ) of Au-doped NiO films with Au contents below 1.0 at.% is difficlut to measure by four point probe. The ρ value could be reduced to 30.4 Ω-cm as Au content of 1.4 at.% is added into NiO film. It is reduced significantly to 0.375 Ω-cm as Au content is increased to 13.6 at.%. Further increasing the Au content to 33.7 at.%, the ρ value of NiO film is further decreased to 4 x 10-4 Ω-cm. On the other hand, the transmittance of Au doped NiO films also decreases with increasing Au contents. The transmittance for pure NiO film is as high as 96 %. As the Au contents of 1.4, 13.6, and 33.7 % are added into NiO film, they are decreased drastically to 45 %, 20 %, and 9 % respectively. The XRD patterns of Au-doped NiO films with Au content below 9.6 at.% only appear NiO peaks and their (200) peaks shift slightly to low angle as Au content is increased. When Au content is added to above 9.6 at.%, the NiO crystalline become worse. In addition, further increasing the Au content to above 13.6 at.%, the (111) peak of Au also appears in XRD patterns. This indicating that the Au atoms instead of part of Ni atoms results in the enlargement of NiO lattice for Au-doped NiO film with lower Au contents, but large amount of Au atoms are precipitated from the NiO lattice when the content of Au in the NiO film is increased to above 13.6 at.%.
Joong Hee Lee
S.C. Chen et al., "Effect of Gold Addition on Electrical and Optical Properties of NiO Films by Rf Sputtering", Advanced Materials Research, Vols. 123-125, pp. 647-650, 2010