Role of Nitrogen Additive and Temperature on Growth of Diamond Films from Nanocrystalline to Polycrystalline

Abstract

In this work, the coupled effect of nitrogen addition into CH4/H2 mixtures and surface temperature on diamond growth ranging from large grained polycrystalline to fine-grained nanocrystalline were investigated. Moreover a new growth parameter window for simultaneous growth of nanocrystalline diamond (NCD) and {100} textured large-grained diamond films was developed by using a high power high pressure 5 kW microwave plasma assisted chemical vapor deposition (MPCVD) reactor. Scanning electron microscope (SEM), Raman spectroscopy, and X-ray diffraction (XRD) are employed to characterize the morphology, crystalline quality and texture of the diamond samples. Our results can be grouped by two catalogs: First, deposition run without and with 0.24% N2 addition, while keeping all the other parameters constant, resulted in a high quality transparent large-grained polycrystalline diamond film and a NCD film, respectively. This result clearly evidences nitrogen induced nanocrystallinity. Then, two different substrate surface temperatures were obtained by overlapping a small silicon slice on the top centre of a large silicon wafer of 5.08 cm in diameter in only one deposition run using 0.24% N2 addition and the same set of parameters as the previous runs. From this growth run, a NCD film of growth rate around 2.3 microm/h was obtained at low temperature, while a {100} textured large-grained diamond film of much higher growth rate about 10.4 microm/h was grown at high temperature. These results not only confirm the reproducibility of NCD by N2 addition, but also indicate that distinct growth modes were involved at different substrate temperatures with 0.24% nitrogen addition, or coupled effect of nitrogen addition and temperature on the growth of CVD diamond films happened. Finite element method (FEM) analysis was employed to simulate the temperature gradient and distribution on these two samples, and based on this simulation and other simulation results in the literature, the growth mechanism is briefly discussed.

Nanoscale Investigation on the Improvement of Electrical Properties of Boron-Doped Diamond Nanostructures for High-Performance Plasma Displays

“…The increase in electrical conductivity can be attributed to the thermal excitation of the charge carriers when T M is increased . Importantly, the value of σ increases with an increase in temperature and reaches a maximum of ∼7.9 × 10 3 S/cm for BMCD L at 573 K. Figure b,e shows a similar upward trend in the n h values of the diamond samples as the T M increases.…”

“…In contrast, the BUNCD P films contain nanosized diamond grains (Figure b I ). The grain size of the BUNCD P film is approximately 10–15 nm (Figure b II ), and the film thickness is 4.5 μm (Figure b III ) . These BMCD P and BUNCD P films were subjected to RIE to fabricate the 1D nanostructures.…”

Properties of ultrananocrystalline diamond grown under different deposition conditions

“…The second most common way to NCD film deposition is small nitrogen addition to the working gas mixture. According to scientific reports, nitrogen can both improve the quality and deposition rate of the diamond coating and be the reason for the micro-to nanocrystalline structure transition [9][10][11][12].…”