Physical, optical and electrical studies on hybrid Ag NPs/NiSi NWs electrode as a DNA template for biosensor

By means of Chemical Vapor Deposition (CVD), Nickel silicide nanowires (NiSi NWs) were grown on silica substrate followed by a solid-diffusion controlled growth mechanism at different substrate temperatures ranging from 400 to 520 degrees C. The NWs were then subsequently decorated with Ag nanoparticles (Ag NPs) via a simple thermal evaporation technique. The morphologies of the NiSi NWs and Ag NPs/NiSi NWs showed noticeable dependence on the growth substrate temperatures. NiSi NWs grown at 470 degrees C exhibited the highest NW density with a uniform decoration of spherical Ag NPs of similar to 13.7 +/- 1.5 nm of diameter. The Ag NPs/NiSi NWs appeared to exhibit a better crystallinity compared to the as-grown NiSi NWs, which could be attributed to metal induced crystallization. Moreover, the decoration of Ag NPs on NiSi NWs showed a significant enhancement in Raman peak intensities mainly in the Ni2Si, NiSi, and NiSi2 phases. The Ag NPs/NiSi NWs demonstrated a well-defined surface plasmon resonance absorption bands centered at around 420 nm, which elucidate the effectiveness of the decoration of Ag NPs on NiSi NW surfaces with a thin amorphous dielectric barrier layer. Using current-voltage (I-V) measurement, Ag NPs/NiSi NWs and NiSi NWs shown to exhibit a surface type Schottky diode with rectifying behavior. The values of ideality factor for the NiSi NWs and Ag NPs/NiSi NWs Schottky diodes were calculated to be 6.992 and 2.559 respectively. Additionally, the values of series resistances were also calculated, where the series resistance obtained are (similar to)91.856 and (similar to)38.697 k Omega/ for NiSi NWs and Ag NPs/NiSi NWs DNA electrodes, respectively.