Photoluminescence Properties of Nanocrystalline Diamond Grown By MPECVD in CH4/H2/N2 Ambient

Abstract

We report on the photoluminescence (PL) and transmission properties of 3 diamond film samples that were lightly doped with nitrogen at varying film growth rates and compare with a 4th diamond sample that had no nitrogen fed into the reactant gas during deposition. For the given film compositions, the PL spectra were qualitatively different, showing significant influence by the presence of nitrogen. Transmission data were collected in the UV-IR range and revealed that the non-nitrogenated sample is much brighter in the IR range than the other 3 doped films. The improved brightness is attributed to a lower number of free carriers, impurities, and lattice vibrations. Raman spectroscopy is used to identify the carbon and impurity bonding types. The effect of nitrogen on electrons is discussed further in terms of field emission turn-on field performance. These results may be used to develop diamond optical systems in the short wavelength infrared range.