Which statement best describes CVD diamond growth?

• A. They are grown by dissolving carbon in a molten metal.
• B. They require none of the parameters used in CVD.
• C. They are grown under high magnetic fields.
• D. They are grown layer by layer using a gaseous carbon source in a reactor, with hydrogen, a substrate, an energy source, and a heating element.

Answer: (D)

CVD diamond growth is a process where carbon is deposited from a gas phase onto a substrate inside a reactor, using an energy source to drive the chemical reactions and a heating element to reach the necessary temperatures. Hydrogen is included in the gas mix to stabilize diamond growth and help remove non-diamond carbon, promoting clean, layered deposition on the substrate. This description captures the essential setup: a gaseous carbon source, a reactor environment, a substrate, energy input (like microwave/plasma or glow discharge), and heating to the right temperature. The other statements don’t fit: dissolving carbon in a molten metal describes HPHT growth, the idea that no parameters are required contradicts how CVD relies on a controlled gas environment, and growing under high magnetic fields isn’t characteristic of standard CVD diamond synthesis.