Activation energies for the growth of diamond films and the renucleation of diamond grains during film growth

Abstract

The effect of substrate temperature upon the growth rate and the properties of diamond thin films grown with different grains sizes is explored. An argon-free and argon-rich gas mixture of methane and hydrogen is used in a hot filament chemical vapor deposition reactor. Characterization of the films is accomplished by scanning electron microscopy, Raman spectroscopy and high-resolution x-ray diffraction. Arrhenius plots of the mass gain, thickness growth, and renucleation rate as a function of the substrate temperature are used to obtain the values of the activation energies. An extensive comparison of the activation energy values obtained in this study with those found in the literature suggests that there are distinct common trends for microcrystalline and ballaslike diamond growth. Besides the activation energy values, the morphology, crystallite size, sp2 quantification, mass gain, thickness growth, and renucleation rate present similar tendencies with the substrate temperature, despite a large variation in the gas mixture composition. Included is a discussion of the possible reasons for these observations.