Electron paramagnetic resonance study of hydrogen-incorporated ultrananocrystalline diamond thin films

Abstract

Hydrogen-incorporated ultrananocrystalline diamond (UNCD) thin films have been deposited in microwave plasma enhanced chemical vapor deposition (MPECVD) system with various hydrogen concentrations in the Ar/ CH4 gas mixture, and characterized by several techniques including electron paramagnetic resonance (EPR), Raman spectroscopy, scanning electron microscope (SEM), and dc conductivity measurements. The EPR spectrum of diamond film was composed of two Lorentzian lines with different g factors. When hydrogen concentration in the plasma increased during diamond growth, the spin density of the narrow line decreased, whereas the spin density of the broad signal remained roughly constant. We propose that the two EPR components can be attributed to two different phases in the diamond film, i.e., the narrow line is originated from the highly defective grain boundary region and the broad line is related to the defects in the diamond grains. © 2007 American Institute of Physics.