Controlling defects in fine-grained sputtered nickel catalyst for graphene growth

Abstract

Sputter-prepared nickel (Ni) films can lose more than half their starting thickness due to evaporation in hydrogen (H2) annealing environments. The loss rate of the sputtered Ni films during the chemical vapor deposition growth of graphene has not been reported earlier. The evaporation rate of sputtered Ni film with the amorphous, mixed, preferred ⟨111⟩ texture was experimentally determined to be 20, 11, and 6 nm/m, respectively. An increase of argon mixture in H2 was found to reduce pitting defects in the films during annealing. The quality of grown graphene on top of the Ni improved when the growth temperature was raised from 900 to 1000 °C, as monitored by Raman spectroscopy. More importantly, loss in the starting Ni film thickness can inhibit the growth of graphene layers. By maintaining the growth of the graphene to two layers or less, a high optical transparency of 95% or better can be achieved.