TY - JOUR
T1 - Microwave N2 plasma nitridation of H-diamond (1 1 1) surface studied by ex situ XPS, HREELS, UPS, TPD, LEED and DFT
AU - Kumar Kuntumalla, Mohan
AU - Zheng, Yusen
AU - Attrash, Mohammed
AU - Gani, Gilad
AU - Michaelson, Shaul
AU - Huang, Kai
AU - Hoffman, Alon
PY - 2022/7/1
Y1 - 2022/7/1
N2 - We report on an experimental investigation and density functional theory (DFT) modeling of the physico-chemical properties of nitrided diamond (1 1 1) surface prepared by exposing a hydrogenated diamond (1 1 1) surface to high purity nitrogen microwave plasma (MW(N2)). Ex-situ X-ray photoelectron spectroscopic analysis showed that the maximum nitrogen coverage is ∼ 1/4 monolayer alongside coadsorbed hydrogen, as corroborated by high-resolution electron energy loss spectroscopy (HREELS). The observed broad peak at ∼ 630 °C in the N2 temperature programmed desorption spectrum suggests that nitrogen desorption substantially occurs below 700 °C. As nitride surface exhibits an increase in electron affinity/work function compared to the hydrogenated surface. Low energy electron diffraction of the nitride surface exhibits a 1 × 1 pattern, which confirms that the MW(N2) exposure results in low-level damage to the diamond (1 1 1) surface; these results complement well with the presence of 1st order optical phonon peak (∼300 meV), the characteristic signature of a highly ordered diamond surface, on the HREEL spectrum. DFT simulations reveal that it is facile for nitrogen to insert into the Csingle bondH bond on H-diamond (1 1 1), forming NH(ad) species adsorbed over C(1 1 1), which dimerizes into NH-NH(ad) at increasing coverages. The computed modes of vibration are in qualitative agreement with the HREELS data.
AB - We report on an experimental investigation and density functional theory (DFT) modeling of the physico-chemical properties of nitrided diamond (1 1 1) surface prepared by exposing a hydrogenated diamond (1 1 1) surface to high purity nitrogen microwave plasma (MW(N2)). Ex-situ X-ray photoelectron spectroscopic analysis showed that the maximum nitrogen coverage is ∼ 1/4 monolayer alongside coadsorbed hydrogen, as corroborated by high-resolution electron energy loss spectroscopy (HREELS). The observed broad peak at ∼ 630 °C in the N2 temperature programmed desorption spectrum suggests that nitrogen desorption substantially occurs below 700 °C. As nitride surface exhibits an increase in electron affinity/work function compared to the hydrogenated surface. Low energy electron diffraction of the nitride surface exhibits a 1 × 1 pattern, which confirms that the MW(N2) exposure results in low-level damage to the diamond (1 1 1) surface; these results complement well with the presence of 1st order optical phonon peak (∼300 meV), the characteristic signature of a highly ordered diamond surface, on the HREEL spectrum. DFT simulations reveal that it is facile for nitrogen to insert into the Csingle bondH bond on H-diamond (1 1 1), forming NH(ad) species adsorbed over C(1 1 1), which dimerizes into NH-NH(ad) at increasing coverages. The computed modes of vibration are in qualitative agreement with the HREELS data.
KW - Diamond (1 1 1) surface
KW - Nitrogen termination
KW - Microwave plasma
KW - Photoelectron spectroscopy
KW - Low energy electron diffraction
KW - High resolution electron energy loss spectroscopy
KW - Density functional theory
U2 - 10.1016/j.apsusc.2022.154085
DO - 10.1016/j.apsusc.2022.154085
M3 - 文章
SN - 0169-4332
JO - Applied Surface Science
JF - Applied Surface Science
ER -