A surface etching for synthetic diamonds with nano-thick Ni films and low temperature annealing

Ni (100 nm thick) was deposited onto synthesized diamonds to fabricate etched diamonds. Next, those diamonds were annealed at varying temperatures (400 1200°C) for 30 minutes and then immersed in 30 wt% HNO3 to remove the Ni layers. The etched properties of the diamonds were examined with FE-SEM, micro-Raman, and VSM. The FE-SEM results showed that the Ni agglomerated at a low annealing temperature (400°C), and self-aligned hemisphere dots formed at an annealing temperature of 800°C. Those dots became smaller with a bimodal distribution as the annealing temperature increased. After stripping the Ni layers, etch pits and trigons formed with annealing temperatures above 400°C on the surface of the diamonds. However, surface graphite layers existed above 1000°C. The B-H loop results showed that the coercivity of the samples increased to 320 Oe (from 37 Oe) when the annealing temperature increased to 600°C and then, decreased to 150 Oe with elevated annealing temperatures. This result indicates that the coercivity was affected by magnetic domain pinning at temperatures below 600°C and single domain behavior at elevated temperatures above 800°C consistent with the microstructure results. Thus, the results of this study show that the surface of diamonds can be etched.