Nickel thin film preparation and its characterization as catalyst for HWC-in plasma-PECVD-growth graphene

Nickel thin film, aimed at catalyst layer for HWC-in plasma-PECVD-growth of graphene, has been deposited on SiO2 glass of microscope slide by thermal evaporation method. The thickness of the as-deposited Ni films was not uniform ranging from 200 nm to 700 nm as revealed from cross sectional SEM image. To reduce the film thickness and improve the crystal quality of the films, the samples were annealed in the furnace with three different temperatures, T = 400 °C, 500 °C, and 600 °C, for three hours. SEM images of the post-treatment indicated that the film thickness decreased to about 100–200 nm after annealed at 500 °C for 3 h. Increasing the annealing temperature to 600 °C leads the nickel atoms out of the substrate so that it leaves the substrate without nickel thin film anymore. The disappearing of the Nickel film after annealing at temperature 600 °C was confirmed by EDS spectrum examination which showed that there was no nickel element in the sample. Due to the loss of nickel thin film after annealing at 600 °C, we set the annealing temperature at 500 °C and optimized duration of annealing. It was found that after annealing for 4 h the obtained thickness of thin film was averagely 44 ± 6 nm with some spread piles on the film. Increasing annealing duration to 5 h lead to increasing the thickness of thin film nickel to be 66 ± 14 nm which seems contradict with our expectation. However, the tens order magnitude of thin film thickness obtained is the expected result for graphene growth.