Structure of a diamond deposited from microwave plasma by a new gas-jet method

Diamond coatings on a molybdenum substrate were obtained by gas-phase deposition from a high-speed jet of activated gases. In the most common case, diamond film is formed as a result of the appearance of discrete nuclei on the substrate, their growing and competing. We observed the formation of coatings consisting of separate isometric aggregates with different types of packaging (111) or (100) plates depending on the process parameters (gas flow, the H-2/CH4 ratio, the substrate temperature). The study of coating morphology using optical and electron scanning microscopy suggests that the particles were in the gas phase for a long time and increased to the size of tens of microns, and then deposited on the substrate. This process can be explained by the charged state of the particles, according to the charged cluster model of Hwang (1996). The study of the structure and phase composition by XRD and Raman spectroscopy revealed amorphous carbon, disordered and crystalline graphite, molybdenum carbide with the dominant contribution of diamond). The broadband luminescence of the coating under UV excitation is related to amorphous carbon, whereas 532 nm excitation causes the glow of vacancy centers such as (NV-) and (SiV-).

Automated summary

Diamond coatings were obtained on a molybdenum substrate through gas-phase deposition, with the formation of nuclei and their growth and competition being key steps. The study of coating morphology revealed the growth and deposition process of particles in the gas phase, while XRD and Raman spectroscopy analysis identified the structure and composition of the coatings.