Correlation between surface stochastic parameters and field emission property of NiO nanorods

In this research, nickel thin films have been deposited on Si (1 0 0) substrate using the dc sputtering method. Then, the deposited layers were annealed in different temperatures to oxidize and crystallize the as prepared layers. Scanning electron microscopy (SEM) analysis indicated that the nanorod shape of the nickel oxides has grown on the substrate and x-ray photoelectron spectroscopy determined the formation of stoichiometric NiO on the surface. Field emission (FE) measurements of the NiO nanorods exhibited the lowest turn-on electric field at about 3.8 V mu m(-1) in the 300 mu m vacuum gap. Moreover, the field enhancement factor (beta) was measured of about 4109 for this sample. The FE measurements in different vacuum gaps (d) indicated that the relationship between 1/beta and 1/d is a linear function which obeys a two-region FE model. The effect of annealing temperature on degree of surface roughness of the nanorods used in FE measurements was also studied by employing the atomic force microscopy (AFM) technique and its stochastic analysis. Based on AFM/SEM topographical measurements and surface stochastic analysis, it was determined that beta increased with decreasing the roughness exponent (gamma).