Diamond film deposition by a substrate-stabilized flat flame

Abstract

Abstract A diamond film deposition system with a C2H2H2O2 flat flame was improved to extend the stable region of the flat flame in several deposition factors: the volume ratio of C2H2 to O2 in the reactant gas (C/O ratio), the substrate temperature (Ts), the total reactant gas flow rate (Vg) and the distance between the burner nozzle tip and the substrate (L). Effects of these deposition factors on the deposition rate and the quality of the diamond film were studied. As Ts increased, the deposition rate increased at the expense of the film quality for the C/O ratios of 1.03 and 1.05 while the deposition rate increased without deterioration of the film quality for the C/O ratio of 1.01. The maximum deposition rate was 80–90 μm h−1 for the C/O ratios of 1.03 and 1.05 and 50 μm h−1 for the C/O ratio of 1.01. When the Vg increased by 30%, the deposition rate and the uniformly deposited area increased by ca 90% and 30%, respectively. The uniformly deposited area was found to nearly coincide with the flat flame area. For the thermal stress-free self-standing polycrystalline diamond films, it was found that the full width at half-maximum (FWHM) of the diamond Raman peak at 1332 cm−1 becomes narrower with decreasing the amount of the non-diamond carbon in the films. The narrowest FWHM of 2.6 cm−1 obtained in this work was comparable to that of a high quality single crystal diamond.