Theoretic Studies On Nanodiamonds And Experimental Preparation For B-C-N Thin Films

The heat of formation and infrared spectra of hydrogenated nanodiamonds with different morphologies (up to 1.92 nm in diameter) has been investigated using density functional theory (DFT). Preferential growth orientation along <111> orientations corresponding to an octahedral shape was observed according to the computed heats of formation. The simulated IR spectra show distinct dependence on both size and morphology of the nanodiamonds. The major IR peaks in the region of 900-1300 cm^-1 shift toward high Wavenumber as the nanocluster size increases, while the C-H vibrations in the range of 2500-3500 cm^-1 show an opposite trend. The present results would be useful for identifying the size and morphology of nanodiamonds in experimental IR spectroscopy.Amorphous B-C-N thin films were synthesized by radio frequency reactive magnetron sputtering from boron and graphite targets via varying the temperature and bias voltage applied to the silicon (100) substrate. Characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the bonding contents showed remarkable changes as varying the bias voltage applied to the substrate at 400℃. The bonding contents tuned by temperature and bias voltage reveal the atomic configurations which significantly determine the physical properties of materials. A new perspective was provided here to understand the structures of B-C-N films by counting the bonding contents.